Pioneering Work On Fusarium Head Blight In Rye

-

Based on the study’s preliminary results, some rye lines, like the one shown here, are susceptible to Fusarium head blight, but most are in the resistant to intermediate range. (Photo: Duoduo Wang, University of Manitoba)

Unlike other cereal crops affected by Fusarium head blight (FHB), very little is known about FHB in fall rye from a Canadian perspective. We don’t know how serious a concern FHB might be in our rye crops. We don’t know which Fusariumspecies are infecting rye. We don’t have FHB ratings for our current rye varieties. And we have limited information on optimal timing for fungicide applications to manage FHB in rye.

So Jamie Larsen with Agriculture and Agri-Food Canada (AAFC) at Lethbridge and Anita Brûlé-Babel with the University of Manitoba have teamed up on a project to develop FHB-related information and tools that rye growers need.

“This research is new territory from a Canadian and even a North American perspective,” says Larsen, who has breeding programs for open-pollinated fall rye and several other cereals.

“Rye has not had a lot of attention from Canadian researchers and growers for a very long time. But the playing field has changed with the new rye hybrids. They are significantly higher yielding, they are shorter, and they are easier to harvest. So now there is renewed interest in rye,” notes Brûlé-Babel. “It’s important to get a sense of how rye responds to Fusarium head blight and whether there is going to be an issue with the disease and what rye growers should do in conditions where Fusariumis a concern.”

Larsen became interested in the issue due to several factors that have emerged in recent years. “Initially when I started working in rye, I had looked at the literature and I thought the disease wasn’t a major problem. Also, the main areas where rye is traditionally grown – north of Swift Current and around the Great Sand Hills area in Saskatchewan – aren’t huge Fusarium head blight areas. And rye has this natural ability to be tolerant to a lot of diseases. So I wasn’t too worried about Fusarium head blight,” he explains.

“But then I sent some rye varieties to Ontario as checks in a triticale experiment. And as I was walking along in those plots, I saw a rye variety with its head completely glued shut and pink with Fusarium. I’d never seen anything like it.” As well, he found out FHB occurs in Prairie rye crops through his work as the coordinator for the fall rye cooperative registration trial. Each year, the trial is grown at 15 locations across Western Canada, and in some years Fusarium-damaged kernels (FDK) have been found in the grain samples from the trials.

Another driver for Larsen was the potential, especially with the new hybrids, to sell more rye into the feed and food markets. To help in realizing that potential, he saw the need to know more about FHB’s impacts on rye yield and quality – particularly since Fusariumspecies can release toxins that can limit the use of grain in feed and food – and the need to develop FHB-resistant rye varieties and other tools to manage the disease.

A widespread concern in Manitoba, Brûlé-Babel conducts screening for FHB resistance as part of her winter wheat breeding program. So Brûlé-Babel and Larsen brought together their different areas of expertise to develop their plans for the project. Also joining the project is KWS, the German company that has developed several hybrid ryes for Canadian growers.

Evaluating Rye Lines for Resistance

Brûlé-Babel is screening fall rye lines for FHB resistance at her FHB nurseries at Winnipeg and Carman. To increase the potential for disease development, her research team inoculates the rye lines with Fusarium graminearum, the most common of several Fusariumspecies that cause FHB in Manitoba cereals.

The FHB responses of the rye lines are measured in three ways: disease levels in the field; FDK levels in the grain; and concentrations in the grain of deoxynivalenol (DON), the primary toxin produced by Fusarium graminearum.

In 2017, they evaluated about 70 rye lines, including materials from Canada, the United States, Germany, Russia and other countries, as well as lines from Larsen’s breeding program and from KWS. Current Canadian rye cultivars are included in the screening so growers will be able to get information on FHB ratings to help in choosing rye varieties for their farms. For 2018, the researchers have added more rye lines from KWS, so the total is now about 130 lines.

The 2017 results showed that FHB definitely occurs in rye and that some lines are more resistant than others.

“Overall, we’re not seeing very many lines that are as susceptible as our susceptible wheat checks. And most of the rye lines are in the resistant to intermediate range,” notes Brûlé-Babel.

The testing for FDK and DON in the 2017 samples will be done in the coming months by KWS. However, based on what Brûlé-Babel’s team observed in the field and as the grain samples were harvested, it appears that FHB infection often tends to cause the rye plant not to set seed. As a result, the FDK levels are lower than would be expected in a wheat crop with similar field infection levels.

Brûlé-Babel had heard anecdotally through their KWS collaborators that DON levels in rye tend to be quite low. She suspects this could turn out to be true if there aren’t many infected kernels in the harvested grain to contribute to DON in the samples.

“So my guess at this point is that the biggest problem from Fusarium head blight for rye producers might turn out to be yield loss as opposed to a crop that you can’t market [due to FDK and DON],” she says.

Once they have two years of data from the nurseries, Larsen will start making crosses with some of the FHB-resistant lines so he can develop new open-pollinated varieties with this trait.

Other Fusarium Species

Brûlé-Babel is also leading two other FHB/rye studies for the project. One study is looking into other Fusariumspecies that cause FHB in rye. “Not a lot is known about which Fusariumspecies infect rye [on the Prairies], so we’ve worked with Maria Antonia Henriquez at AAFC’s Morden Research and Development Centre. She does a Fusariumsurvey every year, collecting diseased plants from [spring wheat and winter wheat fields in Manitoba]. So we asked if she could also collect samples from rye fields,” explains Brûlé-Babel.

One of Brûlé-Babel’s graduate students, Duoduo Wang, has isolated the Fusariumspecies from the Manitoba rye samples. Wang has identified the species based on the appearance of the fungi when grown in the lab, and she will be doing some DNA marker work to confirm the identifications. The preliminary results indicate that the most common species was Fusarium graminearum, but other species were also present.

In 2018, Wang will be doing a greenhouse study to examine the infection process and see how the different Fusariumspecies interact with selected rye cultivars.

Optimizing Fungicide Timing

Wang is also working on the other study, which is investigating fungicide timing for managing FHB in rye. “Very little information is available on fungicide timing for rye for this disease. We need to develop some basis for timing recommendations,” says Brûlé-Babel.

According to Larsen, the general recommendation for fungicide timing for FHB in wheat is to spray two days after heading because wheat plants usually flower about two days after heading. But in rye, flowering might not start until seven to 14 days after heading. In that long heading/flowering period, what is the best time to apply a fungicide?

Brûlé-Babel also points out that, because rye is an outcrossing species, its florets are open for a longer period than the florets of a self-pollinating species like wheat, and it may be that a fungicide might interfere with pollination and seed set in rye.

From the rye lines being screened in the nursery, Wang has selected an FHB-susceptible cultivar, a cultivar with an intermediate response, and an FHB-resistant cultivar to use in the fungicide trials. The trials will take place at Winnipeg and Carman. The fungicide will be Prosaro, a commonly used fungicide that is registered for FHB suppression in wheat and barley.

The trials will compare four fungicide timings: at 50 per cent heading; at 10 per cent anthesis, which is when 10 per cent of the flowers on the spike have extruded anthers; at 80 per cent anthesis; and at six days after flowering. Brûlé-Babel’s team will be inoculating the plants with Fusarium graminearum. The trials will also have two types of check plots: inoculated with no fungicide and non-inoculated with no fungicide.

Larsen hopes they’ll be able to figure out an easy-to-use general rule for FHB fungicide timing in rye similar to the two-days-after-heading guideline for wheat. He adds, “The hybrids are typically a lot more uniform in flowering timing than the open-pollinated ryes, so fungicide timing for open-pollinated ryes might turn out to be a little trickier.”

Practical Results

This pioneering project will lead to practical information, improved varieties and other tools for rye growers in Western Canada and perhaps other regions of the country.

“Providing good information for farmers to make decisions is very important. Part of the reason we’re doing this research is to make sure there won’t be any surprises in terms of potential Fusariumproblems for rye growers,” Brûlé-Babel says. “I’m quite excited about the revival of interest in rye because it’s a very good crop for many uses and definitely contributes to diversification on the landscape.”

This FHB research is part of a larger project led by Larsen on rye disease issues that also includes work on ergot and rust. Saskatchewan’s Agriculture Development Fund, Western Grains Research Foundation, Western Winter Wheat Initiative, Saskatchewan Winter Cereals Development Commission, FP Genetics, KWS and Bayer CropScience are funding the project.

 

AWC Announces $175,000 in Agronomy-Related Research Funding Through Integrated Crop Agronomy Cluster

-

The Alberta Wheat Commission (AWC) is pleased to announce funding commitments of $175,000 over five years through the Integrated Crop Agronomy Cluster (ICAC) to five research projects aimed at developing leading edge agronomic practices for farmers.

Federal Agriculture Minister Lawrence MacAulay recently announced $6.3 million in funding through Agriculture and Agri-Food Canada’s CAP program to add to ICAC’s total investment of $2.6 million.

“AWC invests in cutting edge research that has the potential to improve crop performance,” said Kevin Bender, AWC Chair. “The goal of our investments through ICAC are not only to strengthen agronomic outcomes but also to increase long-term profitability for farmers.”

Chaired by the Western Grains Research Foundation (WGRF) and formed by cropping groups across Canada, ICAC is a cross-commodity agronomy cluster initiative aimed at encouraging increased investment in agronomy-focused innovation. ICAC takes a whole-farm approach to regional and national needs and long-term sustainability innovation including soil, water, air and economics.

AWC-funded projects through ICAC investment include:

  • $20,000: Coordinated monitoring of field crop insect pests in the Prairie Ecosystem
  • $5,000: Prairie Crop Disease Monitoring Network
  • $50,000: Crop sequence effects on fusarium head blight of cereals
  • $50,000 Development of decision support tools for Fusarium Head Blight Management in Western Canada
  • $50,000: Optimizing systems productivity, resilience and sustainability in the major Canadian ecozones

AWC looks forward to providing project summaries and updates as they become available.

Source: The Alberta Wheat Commission 

Genome Canada and AAFC Funding

-

Genome Canada in partnership with Agriculture and Agri-Food Canada (AAFC) has recently launched the 2018 Large-Scale Applied Research Project Competition: Genomics Solutions for Agriculture, Agri-Food, Fisheries and Aquaculture (2018 LSARP).

This funding competition aims to support projects that will use genomics to advance the sustainability, productive capacity, and competitive position of the Canadian agriculture and agri-food & fisheries and aquaculture sectors, and thereby strengthen Canada’s economy and the wellbeing of Canadians. There is approximately $30 million available through Genome Canada, and up to $16 million from AAFC. Successful projects can receive up to $4 million from Genome Canada, and $3 million from AAFC over a maximum of four years, with a 1:1 co-funding ratio to Genome Canada’s contribution.

More information about the Request for Applications can be found on Genome Alberta’s website.

When seeking funding, researchers are encouraged to refer to the priorities and target research outcomes in the Canadian Beef Research and Technology Transfer Strategy.

Deadline for submitting registrations to Genome Alberta is August 7, 2018, and deadline for submitting registrations to Genome Canada is August 16, 2018.

Interested Alberta-based researchers should contact Niall Kerrigan at Genome Alberta.

Source: AAFC

Ramping up Variety Development

-

NRC research officers Polowick (left) and Rajagopalan (right) are investigating the effects of growing wheat plants under accelerated growth conditions. (Photo courtesy National Research Council of Canada)

One of the most time-consuming parts of the crop breeding process is the time needed to grow successive generations of plants. What if we could really speed that up?

That’s the goal of a project at the National Research Council of Canada (NRC). The accelerated growth methods used in this project could potentially trim several years off the breeding process, providing a big boost to the development of improved crop varieties.

“The project’s overall aim is to speed up plant growth so breeders can achieve multiple generations of the crop in a very short time,” explains Dr. Kishore Rajagopalan with the NRC in Saskatoon, who is leading the project. “That will help greatly with plant breeding efforts because plants take quite some time to grow and you need to go through several generations as part of a breeding program.”

For instance, imagine the challenge for a breeder who is trying to address an urgent threat, like a very virulent new strain of a major pathogen. “Sometimes it can take 10 to 13 years to get new varieties out into the marketplace. Pathogens can evolve quickly and spread around the world. They don’t sit around and wait for the breeders to catch up with them. So the faster that the breeders can introduce new forms of disease resistance into a crop, the better,” notes Dr. Patricia Polowick, another NRC researcher involved in accelerated growth studies.

“Accelerated breeding is faster than traditional crop breeding. So if farmers are faced with new threats whether from disease or other means, improved varieties will get to the farmers much faster and they won’t have as much crop loss.”

Acceleration Options

In his project, Rajagopalan’s team is applying multiple methods to speed up wheat growth and looking for the best combination of these methods that will take the plants from seed to flowering and maturity in the shortest time.

One intriguing method involves growing plants under constant light. “The use of continuous light for accelerating crop growth was adopted initially by a group of Australian researchers in collaboration with others around the world. They were inspired by experiments conducted by NASA [National Aeronautics and Space Administration] in the 1980s and 1990s looking at growing plants in controlled environmental conditions including constant light,” Rajagopalan says.

The NASA scientists were experimenting with the use of plants to help maintain human life in space. “In these experiments, they observed a linear effect of light on photosynthetic rate and production of plant biomass. In simple terms, photosynthesis is the process by which a plant converts atmospheric carbon dioxide into storable sugars using energy that comes from sunlight, and in the process it emits oxygen back into the atmosphere. [The scientists observed that] if you increase the supply of light to the plant, then it continues to perform photosynthesis and continues to grow more and faster and produce more biomass,” he notes.

“In addition, in certain plants, especially in cereal crops like wheat and barley, applying continuous light also seems to increase the plant’s development rate. So the plant goes from seed to flowering faster, and you get to the next generation of plants faster. This is simply because constant light could act as a stress factor. When you apply stress to a plant, the plant responds by producing flowers and seeds, and completing its lifecycle as early as possible before it dies or desiccates.”

Rajagopalan notes other environmental stress factors can also accelerate plant development in a similar way. So, along with constant light, the project is testing factors like moisture stress, nutrient availability stress and stress from smaller pot sizes.

The research team is also using a propagation method called embryo rescue to go more quickly from one generation to the next. “We harvest seeds before they are fully mature and dried, and harvest the embryos from these grains, put the embryos on nutrient media plates and get seedlings from them. That can save us a few weeks, instead of waiting for the grains to mature and dry,” Rajagopalan explains.

Speed Breeding, Canadian Style

The project’s four objectives mainly relate to determining optimal procedures for accelerating growth of Canadian wheats, seeing how many generations they can get per year, and increasing understanding of the effects of these accelerated growth conditions on plants.

“The first objective is to evaluate the rust and Fusarium head blight resistance of different Canadian wheat varieties when grown under normal conditions compared with the accelerated growth conditions,” says Rajagopalan. “We want to understand how important traits like disease resistance are affected by these accelerated growth conditions so that we can use these conditions for breeding for those traits.”

They are focusing on Fusarium head blight and rust because of the relevance of these diseases to Canadian wheat production. “We looked at Fusarium head blight because it’s an increasing problem in the wheat-growing regions in Western Canada. The statistics from the last 10 years show the incidence of Fusarium head blight in wheat in Canada has increased almost every year; 2016 was a particularly bad year. Not only does this disease reduce yields but it can also produce toxins, like deoxynivalenol (DON), which can downgrade grain quality and affect the marketability of the grain. So it’s a pretty devastating disease economically,” he says.

“That’s why many researchers here at the NRC and in other organizations are working to find new sources of resistance against Fusarium head blight in wheat. And we want to be able to quickly deploy those novel traits into varieties that are being created, so those varieties can respond to this increasing threat in Canadian farming. By using accelerated breeding, we believe we can bring these traits to the market earlier than is currently possible.”

Like Fusarium head blight, rust is a major disease concern in Prairie wheat crops, and many Canadian researchers are working on rust resistance. Rajagopalan’s project is targeting leaf rust, a common disease in wheat. Under conditions that favour this disease, susceptible wheat varieties can suffer very serious yield losses. Over the years, several leaf rust resistance genes have been introduced into Canadian wheat cultivars and then the pathogen has evolved to defeat that resistance.

“Rapid deployment of new rust resistance genes is essential for fighting this pathogen. And again, speed breeding would be the way to address that.”

The project’s second objective is to see if responses to the accelerated growth methods vary among different wheat varieties. This extensive work involves testing multiple Canadian varieties of bread wheat and durum wheat and determining which combination of acceleration methods is best for each cultivar. “We want to see if we can do any tailoring of conditions for particular varieties,” notes Rajagopalan.

The third objective is to rapidly generate a recombinant inbred line population under accelerated growth conditions. Such lines are very useful for mapping traits in a plant’s genome. The lines generated in Rajagopalan’s project will be used in other projects to characterize resistance genes for rust diseases in wheat.

“And the fourth objective is to evaluate long-term changes induced when plants are grown for multiple generations under accelerated growth conditions,” says Rajagopalan. “We want to see if any long-lasting effects are happening in the plants compared to plants grown under normal conditions.”

Polowick adds, “One of the reasons we want to look at the long-term effects is because we are putting the plants under a lot of stress.” Breeders will want to be sure plants grown under induced stresses to accelerate their growth will respond to things like diseases and insect pests in the same way when they are grown under normal conditions.

Boosting a Breeding Revolution

This two-year project started in April 2017, and Rajagopalan’s team has already completed two of the objectives. “We have completed the testing of the effects of Fusarium and rust resistance in different varieties under normal and accelerated growth conditions. And we have completed the very large-scale study to understand the effects of accelerated growth conditions on various wheat varieties. So we have a really good understanding of what conditions work best for the multiple varieties of durum and bread wheat that we have tested.” The researchers are currently working on the other two objectives.

The effects of the accelerated growth conditions are very impressive so far.

“Right now, we are getting about five to six generations of wheat within a year using these conditions. For plants grown under normal conditions [in a greenhouse], you will get around two to three generations per year. So you can reduce the generation time of the plant by half by adopting these conditions,” says Rajagopalan.

There is already interest in applying speed breeding beyond Rajagopalan’s project. “I’m running a parallel study with a private breeding company using the same accelerated breeding ideas with some of their wheat lines,” Polowick explains. “This concept has been heavily adopted by the plant breeding industry in places like Australia, and we’re hoping that some of our work here will make it more available to the Canadian breeders so Canadian farmers can benefit from our progress.”

Along with the benefit of bringing new varieties to the market sooner, Polowick points to a further advantage. “Some of the other projects within the NRC [and other agencies] use the modern ‘omics’ such as genomics and proteomics, and these technologies have enabled great progress in the identification of novel plant traits whether it is to fight diseases or to mitigate the effects of environmental stresses. So it’s not accelerated growth conditions in isolation; it’s accelerated growth in combination with a lot of the progress being made in other projects that will provide the most benefit to the farmers.”

Alberta Wheat Commission research manager Lauren Comin sees value in this type of research. “Decreasing the time it takes for a variety to be developed is very important for producers. Producers need to be able to be nimble when it comes to choosing a variety. For example, resistance to abiotic and biotic stress plays an important role in selection. We are seeing pests adapt over time and currently employed resistance genes are being defeated. At the same time, we are seeing remarkable advancements in pre-breeding and discoveries of new sources of resistance. Shorter variety development times mean that new genes can be deployed and be in a farmer’s field without too much of a lag. Our scientists can respond to changes more quickly, which allows farmers to adapt faster as well.”

Along with the potential for large, rapid steps forward in Canadian wheat varietal improvement, other crops could also benefit from the powerful combination of accelerated breeding and valuable new traits. Australian research shows speed breeding can also work in such crops as barley, chickpea, pea and canola, with the number of possible generations per year depending on the crop type.

“We would love to see wider adoption of these accelerated breeding methods that we are working on in Canadian wheat breeding programs and to also make progress in other crops where this approach is applicable,” Rajagopalan says.

His project is funded by the Saskatchewan Ministry of Agriculture, the Canada-Saskatchewan Growing Forward 2 program, and the National Research Council of Canada.

What Makes Cereal Crops More Stress-Tolerant?

-

Whether barley, wheat, maize or rice: The grass family includes all the major cereals. They are vital for feeding the world’s population. Farmers produce 80 per cent of all plant-based foods from grass crops. This success is due in part to the plants’ ability to adjust more quickly to dry conditions and sustain lack of water better than other plants.

But why are grasses more tolerant to water scarcity? Can other food crops be bred for this property, too, to assure or boost agricultural yields in the future? This could be important in the face of a growing world population and climate change that will entail more periods of dry and hot weather.

The plant researchers Professor Rainer Hedrich, Professor Dietmar Geiger and Dr. Peter Ache from Julius-Maximilians-Universität Würzburg (JMU) in Bavaria, Germany, are looking into these questions. They studied brewing barley to determine why grasses are more stress-tolerant and are therefore “better” crop plants than potatoes and the likes.

Two Amino Acids Make the Difference

The scientists discovered that this difference can be attributed to the protein SLAC1 of the guard cells. Just two amino acids, the building blocks that make up proteins, are responsible for the plant’s drought tolerance. “We now want to find out whether this small difference can be harnessed to make potatoes, tomatoes or rapeseed more tolerant to stress as well,” says Rainer Hedrich.

The new insights have been published in the prestigious journal Current Biology where Hedrich, Geiger and Ache describe how they pinpointed the tiny difference between grasses and other plants.

Ion Transport is a Key Process

The JMU researchers began scrutinizing microscopically small leaf pores called stomata. These openings admit carbon dioxide for photosynthesis into the plant. But they also serve as outlets for water. To prevent losing too much water through evaporation, land plants have learned during evolution to actively open and close their stomata using special guard cells. Membrane proteins such as SLAC1 play a key role in this regulatory process: acting like channels, they guide ions into and out of the cells.

Hedrich is convinced that a basic understanding of the molecular goings-on during ion transport through the plasma membrane of the guard cells is the key to improving the drought tolerance and yields of agricultural crop plants.

Ion Shuttles Make Leaf Pores More Efficient

The stomata of grasses have a special feature: The pore is bordered by two pairs of cells where other plants only have a single cell pair. Grass cereals boast two dumbbell-shaped guard cells that form and regulate the pore. Additionally, they are flanked by two subsidiary cells.

The JMU researchers have demonstrated that the subsidiary cells absorb and store the potassium and chloride from the guard cells when the pore closes. When the stoma opens, they pass the ions back to the guard cells. “Our cereals use the subsidiary cells as a dynamic reservoir for osmotically active ions. This ion shuttle service between guard cell and subsidiary cell allows the plant to regulate the pores particularly efficiently and quickly,” Dietmar Geiger explains.

Two Measuring Systems for More Drought Resistance

There is a second mechanism that makes grasses more tolerant to dry conditions. When water is scarce, plants produce the stress hormone ABA (abscisic acid). Inside the guard cells, it activates the ion channels of the SLAC1 family, thereby initiating the closing of the stomata to prevent the plant from withering within a matter of minutes.

“Interestingly, we found that nitrate must be present in brewing barley and other grass cereals in addition to ABA to enable the pore to close,” Peter Ache says. The nitrate concentration allows the barley to measure the shape the photosynthesis is in. If it works smoothly, nitrate levels are low.

Barley hence relies on two measuring systems: It uses ABA to register water availability and nitrate to assess photosynthesis performance. “By combining the two, the barley is better able than other plants to negotiate between the extremes of ‘dying of hunger’ and ‘dying of thirst’ when facing water scarcity,” Rainer Hedrich explains

Testing the Nitrate Sensor in Other Plants

Which mechanism is responsible for the difference in stoma regulation at the molecular level? To answer this, the researchers analyzed SLAC1 channels of various herbaceous plants compared to grasses. This allowed them to identify the “nitrate sensor” of the grasses: It is comprised of a motif of two amino acids which first occurred in moss during evolution and was subsequently further optimized to give the guard cells their unique properties.

In a next step, the team of researchers wants to establish whether herbaceous agricultural crops also benefit from having a nitrate sensor. To achieve this, the scientists want to fit Arabidopsis plants that lack the SLAC1 channel with the SLAC1 channel of barley. “If this step increases their stress tolerance, we can consider breeding optimized potatoes, tomatoes or rapeseed,” Hedrich says.

Clubbing Clubroot

-

Photo: Janet Kanters

On the Prairies, clubroot appeared in Alberta in 2003, in Saskatchewan in 2008 and Manitoba in 2013. As any grower can tell you, it’s a nasty canola disease that usually worsens in a field every year, partly because the spores are very easy to spread and so hardy they can survive for up to two decades in the soil. Combine this fact with the strong prices that canola fetches these days – widely encouraging back-to-back or two-year rotations – and you have a big problem.

Companies are certainly moving as quickly as possible to produce seed with effective resistance to clubroot, but breeding to defend against this particular pathogen involves navigating a wide range of complex challenges.

“Clubroot has a very short lifecycle resulting in several generations per season,” explains Dr. Marcus Weidler, vice president of seed operations at Bayer CropScience, “enabling the pathogen to react to changes in its environment very quickly, including new crop resistance genes.”

Dr. Jed Christianson, pathology lead at Monsanto Canada, explains that clubroot’s large and quickly-adapting population sizes means that it takes relatively long canola rotations of three or four years to see significant drops in the number of viable spores in the soil, and very long rotations of over 10 years for spores to effectively disappear.

“Each gall produced on a canola root can contain billions of spores,” he says. “So, given the numbers of spores generated, even very rare events like the emergence of individual spores that have gained the ability to infect resistant canola will happen over a fairly short number of cropping cycles. A one in a billion event doesn’t seem that unlikely to happen when you’re given 20 billion chances.”

Combine this with the fact not all clubroot pathotypes (races) have been identified, and it’s therefore difficult, explains Weidler, to develop a canola variety that is resistant to all potential pathotypes to which a plant may be exposed.

Dr. Igor Falak reminds us that it was in 2013 that a new clubroot pathotype was identified, one to which all canola varieties on the market carrying resistance to the original 2003 pathotype were susceptible. Although hybrids with the initial type of resistance continue to hold their own on most infested acres, the number of fields with the new pathotype is increasing annually. Falak, senior research scientist with Corteva Agriscience, blames this situation on “years of canola-on-canola.”

In addition, he notes that although clubroot “is similar to another disease of canola (blackleg), where canola products may carry race specific resistance,” clubroot-resistant canola varieties “do not have ‘fallback’ resistance mechanisms, unlike blackleg-resistant products that also have a different type of stable resistance.”

More breeding challenges are found in the fact that because canola plants carry no clubroot resistance genes, all the major seed companies are actively testing resistance genes found in rutabaga, cabbage and turnip. However, Weidler notes that because these species are only remotely related to canola, it’s far from easy to transfer genes between them without also transferring additional unwanted genetic “baggage” that negatively impacts yield, canola quality or agronomics.

If all this wasn’t enough, clubroot is a challenging organism to deal with, having unique characteristics – described by Weidler as a form of life “somewhere between a bacterium and a fungus.”

Christianson concludes that the biggest challenge in creating clubroot-resistant canola seed is to introduce resistance “while continuing to improve hybrid performance for yield, maturity, standability, resistance to other diseases, harvestability, seed quality and all of the other attributes that are important to growers’ success.”

Breeding Steps to Develop Clubroot-Resistant Canola Seed

Christianson says the steps involved in breeding clubroot-resistant varieties are relatively simple, and that any breakthroughs relating to resistance genes “are really just the discovery and characterization of more of them through concerted screening efforts.”

The entire process is a matter of crossbreeding canola with resistant relatives through normal pollination procedures and recovering offspring that are clubroot-resistant. “Those offspring then have to be crossed with canola again and again through many generations, selecting the resistant offspring at each generation for use in the next cycle to obtain plants that maintain resistance, but have recovered the characteristics of high-performing canola,” Christianson explains.

Weidler adds that unwanted genetic material from the resistance donor that negatively impacts the agronomic performance of the offspring is removed through several crossings of the offspring with elite parent stock. “Using molecular breeding tools, we can check the progress towards the end goal,” he notes. “Ideally, only the genetic sequence conferring clubroot resistance has been transferred and no other parts of the donor genome remain in the offspring.”

Breeding Progress

DowDupont was the first company in Canada to market clubroot resistant hybrids in 2009 (45H29).

“Our hybrids have multi-source and multi-race resistance to clubroot, and have a high level of resistance to the most prevalent clubroot race – race 3 – along with resistance to races 2, 5, 6 and 8,” Falak notes. “We have five hybrids with clubroot resistance: 45H29, 45H33, 45CS40, 45CM36 and 45H37. Pioneer hybrid 45CM36 is one of our newest products that contains a new source of clubroot resistance that confers resistance to both the initial type and new pathotypes, and can be rotated with the original resistant hybrids.”

Hybrid 45CM36 was launched in 2017 and is widely available to western Canadian famers for the 2018 growing season.

For its part, Bayer CropScience has “identified several new potential resistance sources,” says Weidler, “and we have been able to demonstrate that these are different from what is currently on the market.”

Christianson says that as Monsanto nears “actual commercial entry into the marketplace, we will have more to share about how second-generation resistance fits in with existing resistance traits to provide a sound disease management strategy.”

No matter what resistant canola varieties are marketed, no company can predict how long a new variety will last before it’s compromised. This depends on too many factors, explains Weidler, including the resistance gene, environmental conditions and management practices.

All the companies strongly agree that the existence of varieties with resistance is only part of the clubroot solution.

Weidler emphasizes the importance of an integrated disease management approach for clubroot, and fully supports the recommendations of the Canola Council of Canada.

Falak and Christianson echo the sentiment. “All resistance traits will be effective for longer periods of time if they are used judiciously,” says Christianson. “Choosing resistant seed is only one part of a successful disease management strategy. Growers need to include crop rotation, field scouting and early detection of clubroot, and minimizing soil movement between fields on equipment.”

Falak agrees. He says following a proper canola rotation as well as rotation of resistance genes, combined with preventing soil movement and other agronomic measures “would enable sustainable clubroot management that would prolong efficacy of any new resistance sources that are introduced.”

Wind Farms Positively Impact Crops, U.S. Study Says

-

Photo: Janet Kanters

Iowa State University researchers have found that wind turbines located in agricultural fields are a plus for the crops growing around them.

The overall effects on crops growing in wind farms appear to be positive said Gene Takle, Iowa State agronomy professor. He has led a team of plant and soil scientist along with extension specialists who have been looking into the effects since 2009.

They started their work after seeing more wind farms and turbines pop up around the state. The new land use was positive for the landowners where they were located, but the researchers wondered if it was the same for the farmers growing crops.

“It’s unusual because we’re continuing the previous land use and we’re adding another,” Takle says. “We’re sort of double-cropping because these can be thought of two forms of energy production. The Chinese do this when they plant soybeans in between horticultural crops. We’re planting turbines.”

If the turbines change the microclimate for corn and soybeans, the team wanted to learn if it is a big enough change to be measured and the potential impacts.

Takle says wind blowing across a corn or soybean field without turbines creates a certain turbulence that carries moisture from the transpiring crop, which rises into the atmosphere and pulls down cooler, drier air. At night the wind is calmer and the land cools.

Turbines take some of the wind energy, slowing it down but increasing its turbulence so it interacts with the crop more, possibly increasing evaporation from the crop or moving carbon dioxide down into the crop.

“The biggest changes are at night and that’s because during the day there’s a lot of chaotic turbulence, just because the sun is heating the surface and the wind is gusty,” Takle says. “At night when it gets pretty calm, the crop cools down and if it’s a humid night you start to get dew formation. If you add the turbines, it looks a little more like the daytime. So the dew formation is delayed and it may start to evaporate sooner.”

Since fungus and mold like a wet environment, the shorter the wet period makes it less favorable for the growth of those potential pathogens. In the fall, the shorter wet period could speed up harvesting because farmers typically have to wait for soybeans to dry in the morning.

Another factor is that turbines bring warmer air down to interact with the cool air near the surface. Throughout the wind farm, the surface is a little bit warmer which inhibits dew formation.”

“Satellites can measure surface temperatures and you can see little dots across the state of Iowa and locate every wind farm because they’re slightly warmer than the surrounding area. So we know it has an effect that’s large enough to be seen there,” he says.

Another plus is the air pressure fluctuation measured around wind turbines.

Takle says there is a lot of carbon dioxide in the top few feet of soil — as much as two or three times what is in the air. The movement of air by the turbines pumps air down, and the movement draws carbon dioxide out of the soil so more would be available to the plant for photosynthesis.

The air moving down also creates more plant movement, which increases sunlight penetrating the dense crop canopy.

On the negative side is the tendency of higher temperatures occurring at night in wind farms.

Considering corn, during the day it’s taking in solar energy and carbon dioxide to make plant material. At night it cools down and gives back some of the carbon dioxide, and it gives up more if it’s warmer.

“So the night time warming of the turbines is not a totally good thing,” he says. “Night time temps have been going up over the last 40 years and are becoming a limiting factor for crop yields.”

But overall crops grown in wind farms seem to benefit.

“So there are three ways the crop is being ‘fertilized’ from either the air or from the soil or from increased photosynthesis. We measured increased carbon dioxide uptake during the day, but an increased respiration at night,” he says. “But over the course of the day there was more uptake. So as far as the impact of the turbines on the carbon dioxide processes and the photosynthesis process in the near vicinity of the turbines it’s a net gain.”

His team would like to look at the result of wind movement through a farm as it slows and tends to move up, which could create clouds if the air is warm and moist, and potentially rain.

“Are wind farms a preferential location for cloud formation or something that’s going to provide more rain in an area beyond the wind farm? We don’t know, we have some preliminary measurements that suggest that this is a real effect. Theoretically, you say yes there should be an effect, but is it large enough to be measured or to be important?” Takle asks.

Ag robot speeds data collection, analyses of crops as they grow

-

University of Illinois agricultural and biological engineering professor Girish Chowdhary is leading a team that includes crop scientists, computer scientists and engineers in developing TerraSentia, a crop phenotyping robot. (Photo: L. Brian Stauffer)

A new lightweight, low-cost agricultural robot could transform data collection and field scouting for agronomists, seed companies and farmers.

The TerraSentia crop phenotyping robot, developed by a team of scientists at the University of Illinois (U of I), will be featured at the 2018 Energy Innovation Summit Technology Showcase in National Harbor, Maryland, on March 14.

Traveling autonomously between crop rows, the robot measures the traits of individual plants using a variety of sensors, including cameras, transmitting the data in real time to the operator’s phone or laptop computer. A custom app and tablet computer that come with the robot enable the operator to steer the robot using virtual reality and GPS.

TerraSentia is customizable and teachable, according to the researchers, who currently are developing machine-learning algorithms to “teach” the robot to detect and identify common diseases, and to measure a growing variety of traits, such as plant and corn ear height, leaf area index and biomass.

“These robots will fundamentally change the way people are collecting and utilizing data from their fields,” said U of I agricultural and biological engineering professor Girish Chowdhary. He is leading a team of students, engineers and postdoctoral researchers in development of the robot.

At 24 pounds, TerraSentia is so lightweight that it can roll over young plants without damaging them. The 13-inch-wide robot is also compact and portable: An agronomist could easily toss it on a truck seat or in a car trunk to transport it to the field, Chowdhary said.

Automating data collection and analytics has the potential to improve the breeding pipeline by unlocking the mysteries of why plant varieties respond in very different ways to environmental conditions, said U. of I. plant biology professor Carl Bernacchi, one of the scientists collaborating on the project.

Data collected by the crop-scouting robot could help plant breeders identify the genetic lineages likely to produce the best quality and highest yields in specific locations, Bernacchi said.

He and Stephen P. Long, a Stanley O. Ikenberry Endowed Chair and the Gutgsell Endowed University Professor of Crop Sciences and Plant Biology at Illinois, helped determine which plant characteristics were important for the robot to measure.

“It will be transformative for growers to be able to measure every single plant in the field in a short period of time,” Bernacchi said. “Crop breeders may want to grow thousands of different genotypes, all slightly different from one another, and measure each plant quickly. That’s not possible right now unless you have an army of people – and that costs a lot of time and money and is a very subjective process.

“A robot or swarm of robots could go into a field and do the same types of things that people are doing manually right now, but in a much more objective, faster and less expensive way,” Bernacchi said.

TerraSentia fills “a big gap in the current agricultural equipment market” between massive machinery that cultivates or sprays many acres quickly and human workers who can perform tasks requiring precision but move much more slowly, Chowdhary said.

“There’s a big market for these robots not only in the U.S., where agriculture is a profitable business, but also in developing countries such as Brazil and India, where subsistence farmers struggle with extreme weather conditions such as monsoons and harsh sunlight, along with weeds and pests,” Chowdhary said.

As part of a phased introduction process, several major seed companies, large U.S. universities and overseas partners are field testing 20 of the TerraSentia robots this spring through an early adopter program. Chowdhary said the robot is expected to become available to farmers in about three years, with some models costing less than $5,000.

The robot is being made available to crop scientists and commercial crop breeders for the 2018 breeding season through EarthSense Inc., a startup company that Chowdhary co-founded with Chinmay P. Soman.

A former National Science Foundation postdoctoral fellow at the university, Soman is the chief executive officer of EarthSense, which is based at the U of I Research Park and comprises a growing team of engineers and computer scientists.

Source: University of Illinois at Urbana–Champaign

Pioneering work on Fusarium head blight in rye

-

Based on the study's preliminary results, some rye lines, like the one shown here, are susceptible to Fusarium head blight, but most are in the resistant to intermediate range. (Photo: Duoduo Wang, University of Manitoba)

Unlike other cereal crops affected by Fusarium head blight (FHB), very little is known about FHB in fall rye from a Canadian perspective. We don’t know how serious a concern FHB might be in our rye crops. We don’t know which Fusarium species are infecting rye. We don’t have FHB ratings for our current rye varieties. And we have limited information on optimal timing for fungicide applications to manage FHB in rye.

So Jamie Larsen with Agriculture and Agri-Food Canada (AAFC) at Lethbridge and Anita Brûlé-Babel with the University of Manitoba have teamed up on a project to develop FHB-related information and tools that rye growers need.

“This research is new territory from a Canadian and even a North American perspective,” says Larsen, who has breeding programs for open-pollinated fall rye and several other cereals.

“Rye has not had a lot of attention from Canadian researchers and growers for a very long time. But the playing field has changed with the new rye hybrids. They are significantly higher yielding, they are shorter, and they are easier to harvest. So now there is renewed interest in rye,” notes Brûlé-Babel. “It’s important to get a sense of how rye responds to Fusarium head blight and whether there is going to be an issue with the disease and what rye growers should do in conditions where Fusarium is a concern.”

Larsen became interested in the issue due to several factors that have emerged in recent years. “Initially when I started working in rye, I had looked at the literature and I thought the disease wasn’t a major problem. Also, the main areas where rye is traditionally grown – north of Swift Current and around the Great Sand Hills area in Saskatchewan – aren’t huge Fusarium head blight areas. And rye has this natural ability to be tolerant to a lot of diseases. So I wasn’t too worried about Fusarium head blight,” he explains.

“But then I sent some rye varieties to Ontario as checks in a triticale experiment. And as I was walking along in those plots, I saw a rye variety with its head completely glued shut and pink with Fusarium. I’d never seen anything like it.” As well, he found out FHB occurs in Prairie rye crops through his work as the coordinator for the fall rye cooperative registration trial. Each year, the trial is grown at 15 locations across Western Canada, and in some years Fusarium-damaged kernels (FDK) have been found in the grain samples from the trials.

Another driver for Larsen was the potential, especially with the new hybrids, to sell more rye into the feed and food markets. To help in realizing that potential, he saw the need to know more about FHB’s impacts on rye yield and quality – particularly since Fusarium species can release toxins that can limit the use of grain in feed and food – and the need to develop FHB-resistant rye varieties and other tools to manage the disease.

FHB is not common in the Lethbridge area, but it is a widespread concern in Manitoba, and Brûlé-Babel conducts screening for FHB resistance as part of her winter wheat breeding program. So Brûlé-Babel and Larsen brought together their different areas of expertise to develop their plans for the project. Also joining the project is KWS, the German company that has developed several hybrid ryes for Canadian growers.

Evaluating Rye Lines for Resistance

Brûlé-Babel is screening fall rye lines for FHB resistance at her FHB nurseries at Winnipeg and Carman. To increase the potential for disease development, her research team inoculates the rye lines with Fusarium graminearum, the most common of several Fusarium species that cause FHB in Manitoba cereals.

The FHB responses of the rye lines are measured in three ways: disease levels in the field; FDK levels in the grain; and concentrations in the grain of deoxynivalenol (DON), the primary toxin produced by Fusarium graminearum.

In 2017, they evaluated about 70 rye lines, including materials from Canada, the United States, Germany, Russia and other countries, as well as lines from Larsen’s breeding program and from KWS. Current Canadian rye cultivars are included in the screening so growers will be able to get information on FHB ratings to help in choosing rye varieties for their farms. For 2018, the researchers have added more rye lines from KWS, so the total is now about 130 lines.

The 2017 results showed that FHB definitely occurs in rye and that some lines are more resistant than others.

“Overall, we’re not seeing very many lines that are as susceptible as our susceptible wheat checks. And most of the rye lines are in the resistant to intermediate range,” notes Brûlé-Babel.

The testing for FDK and DON in the 2017 samples will be done in the coming months by KWS. However, based on what Brûlé-Babel’s team observed in the field and as the grain samples were harvested, it appears that FHB infection often tends to cause the rye plant not to set seed. As a result, the FDK levels are lower than would be expected in a wheat crop with similar field infection levels.

Brûlé-Babel had heard anecdotally through their KWS collaborators that DON levels in rye tend to be quite low. She suspects this could turn out to be true if there aren’t many infected kernels in the harvested grain to contribute to DON in the samples.

“So my guess at this point is that the biggest problem from Fusarium head blight for rye producers might turn out to be yield loss as opposed to a crop that you can’t market [due to FDK and DON],” she says.

Once they have two years of data from the nurseries, Larsen will start making crosses with some of the FHB-resistant lines so he can develop new open-pollinated varieties with this trait.

Other Fusarium Species

Brûlé-Babel is also leading two other FHB/rye studies for the project. One study is looking into other Fusarium species that cause FHB in rye. “Not a lot is known about which Fusarium species infect rye [on the Prairies], so we’ve worked with Maria Antonia Henriquez at AAFC’s Morden Research and Development Centre. She does a Fusarium survey every year, collecting diseased plants from [spring wheat and winter wheat fields in Manitoba]. So we asked if she could also collect samples from rye fields,” explains Brûlé-Babel.

One of Brûlé-Babel’s graduate students, Duoduo Wang, has isolated the Fusarium species from the Manitoba rye samples. Wang has identified the species based on the appearance of the fungi when grown in the lab, and she will be doing some DNA marker work to confirm the identifications. The preliminary results indicate that the most common species was Fusarium graminearum, but other species were also present.

In 2018, Wang will be doing a greenhouse study to examine the infection process and see how the different Fusarium species interact with selected rye cultivars.

Optimizing Fungicide Timing

Wang is also working on the other study, which is investigating fungicide timing for managing FHB in rye. “Very little information is available on fungicide timing for rye for this disease. We need to develop some basis for timing recommendations,” says Brûlé-Babel.

According to Larsen, the general recommendation for fungicide timing for FHB in wheat is to spray two days after heading because wheat plants usually flower about two days after heading. But in rye, flowering might not start until seven to 14 days after heading. In that long heading/flowering period, what is the best time to apply a fungicide?

Brûlé-Babel also points out that, because rye is an outcrossing species, its florets are open for a longer period than the florets of a self-pollinating species like wheat, and it may be that a fungicide might interfere with pollination and seed set in rye.

From the rye lines being screened in the nursery, Wang has selected an FHB-susceptible cultivar, a cultivar with an intermediate response, and an FHB-resistant cultivar to use in the fungicide trials. The trials will take place at Winnipeg and Carman. The fungicide will be Prosaro, a commonly used fungicide that is registered for FHB suppression in wheat and barley.

The trials will compare four fungicide timings: at 50 per cent heading; at 10 per cent anthesis, which is when 10 per cent of the flowers on the spike have extruded anthers; at 80 per cent anthesis; and at six days after flowering. Brûlé-Babel’s team will be inoculating the plants with Fusarium graminearum. The trials will also have two types of check plots: inoculated with no fungicide and non-inoculated with no fungicide.

Larsen hopes they’ll be able to figure out an easy-to-use general rule for FHB fungicide timing in rye similar to the two-days-after-heading guideline for wheat. He adds, “The hybrids are typically a lot more uniform in flowering timing than the open-pollinated ryes, so fungicide timing for open-pollinated ryes might turn out to be a little trickier.”

Practical Results

This pioneering project will lead to practical information, improved varieties and other tools for rye growers in Western Canada and perhaps other regions of the country.

“Providing good information for farmers to make decisions is very important. Part of the reason we’re doing this research is to make sure there won’t be any surprises in terms of potential Fusarium problems for rye growers,” Brûlé-Babel says. “I’m quite excited about the revival of interest in rye because it’s a very good crop for many uses and definitely contributes to diversification on the landscape.”

This FHB research is part of a larger project led by Larsen on rye disease issues that also includes work on ergot and rust. Saskatchewan’s Agriculture Development Fund, Western Grains Research Foundation, Western Winter Wheat Initiative, Saskatchewan Winter Cereals Development Commission, FP Genetics, KWS and Bayer CropScience are funding the project.

Root Microbiome Valuable Key to Plants Surviving Drought

-

Just as the microorganisms in our gut are increasingly recognized as important players in human health and behaviour, new research from the University of Toronto Mississauga (UTM) demonstrates that microorganisms are equally critical to the growth and health of plants. For example, plants that are able to recruit particular bacteria to their root microbiomes are much more drought resistant than their fellows, says UTM PhD candidate Connor Fitzpatrick, of the Department of Biology.

Connor Fitzpatrick

The plant’s root microbiome is the unique community of micro-organisms living in and on plant roots. Similar to the gut microbiome in animal species, the root microbiome is the interface between a plant and the world. The root microbiome is responsible for important functions such as nutrient uptake and signals, important to plant development.

Fitzpatrick’s study is published in the latest issue of the Proceedings of the National Academy of Science. His exploration of the role of the root microbiome in plant health could eventually assist farmers to grow crops under drought-ridden conditions.

For the study, Fitzpatrick grew 30 species of plants found in the Greater Toronto Area from seed in identical soil mixtures in a laboratory setting. These included familiar plants like goldenrod, milkweed and asters. The plants were raised for a full growing season (16 weeks), with each species grown in both permissive and simulated drought conditions.

Fitzpatrick’s research explores the commonalities and differences among the root microbiomes of the various host plant species, dividing the microbiomes into the endosphere (microbes living inside roots) and rhizosphere (microbes living in the soil surrounding roots). He found variation across the 30 species, with related species having more similarity between microbiomes than diverse species.

“It’s as you would expect,” Fitzpatrick says. “Just as there are more similarities between a human’s gut microbiome and an ape’s than between a human’s and a mouse’s, the closer the relationship between plant species, the more similar their root microbiomes. It’s important to document as a way to better understand the evolutionary processes shaping the plant root microbiome.”

In addition to deepening our basic biological understanding of plant evolution and development, the research offers further avenues for study, including how and why some plants recruit bacteria that impact drought resistance while others don’t.

“If plants were able to enrich their root microbiomes with a particular group of bacteria, the Actinobacteria, they grew much better in drought conditions,” says Fitzpatrick. “All of our plants had access to this group of bacteria, but they also needed to have the ability to recruit it from the soil.”

In another finding that is consistent with the practice of crop rotation, Fitzpatrick showed that the more similar the composition of a plant’s root microbiome to that of the previous generation of a plant grown in that soil, the more the second-generation plant suffered.

“There is a complex web of interactions taking place that is difficult to disentangle and requires further inquiry,” Fitzpatrick says.

“Practically speaking, we need to understand how to sustain plants with all of the mounting stressors today, such as drought and an increase in pathogens (e.g., plant disease),” Fitzpatrick says. “The efforts to mitigate these issues are expensive and short-lived or very damaging to the environment. If we can harness naturally occurring interactions for these purposes, we’ll be much better off.”

Source: University of Toronto