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Ontario Grain Farmer Magazine

Enhancing resistance to Fusarium head blight and stem rust in Ontario spring wheat germplasm

Principal Investigator: George Fedak  

Research Institution: Agriculture and Agri-Food Canada

Timeline: April 2013 – March 2018

Objectives:

  • To locate unique genes for Fusarium head blight (FHB) resistance in alien species, introgress them into wheat, map the location on the wheat chromosome, and identify markers for the genes that can be used to manipulate / transfer / pyramid these genes in the future.
  • To pyramid existing genes for resistance to Ug99 to provide durable long-range resistance.
  • To map the leaf rust resistance that was introgressed from Triticum monococcum. This is timely since stripe rust prevalence is increasing in Canada and was detected in Ontario for the first time.

Impacts:

  • Crosses have been made, using selected lines from mapping populations, to begin the process of pyramiding the unique FHB resistance QTL. The pyramids will eventually enter spring and winter wheat breeding programs, leading to commercial cultivars with disease resistance provided by these genes.
  • A total of 48 crosses of Ug99 resistant pyramids were made onto 5 elite cultivars of the Ottawa Research & Development Centre (ORDC) spring wheat program. Seed has been forwarded to breeding programs at Ottawa and Lethbridge. Pyramids have been shared with breeding / genetics programs nationally and internationally.
  • The leaf rust resistance gene Lr71 introgressed from T. monococcum has been crossed onto Lr34 to begin a gene pyramiding exercise. Gene banks at CIMMYT and AAFC Saskatoon have requested the above genetic stock for their holdings.

Scientific Summary:

Fusarium head blight is a ubiquitous disease of cereals in all temperate grain-growing regions of the world. Inheritance of resistance is complex and screening for resistance is confounded by environmental factors. Progress in breeding for resistance has been slow and incremental. To help that situation we took the approach of looking for additional resistance genes in wild relatives of wheat. After many years of intensive labor that involved identifying sources of FHB resistance in alien species, crossing, selection and backcrossing to wheat, FHB resistance has been introgressed from T. monococcum, Aegilops speltoides, Triticum timopheevi, Triticum miguschovae and Aegilops cylindrical. Mapping populations have been set up, mostly as doubled haploids. Arrangements were made with DOW Agrosciences to map the unique resistance genes with SNP markers. The assignment of markers to the resistance genes will permit the use of marker assisted selection in deploying these genes in breeding programs.

Since FHB resistance is controlled by numerous genes with relatively small effects that are under strong environmental influence, breeding for resistance is occurring in incremental steps. Additional variability for resistance has been found in alien species. The alien genes from three of these alien species (T. monococcum, T. timopheevii, T. miguschovae) have been mapped and markers assigned that can be used for marker assisted selection to move these genes within breeding material.

Single genes for disease resistance may only have a longevity of 3-5 years before the pathogen mutates and overcomes the resistance genes. We have initiated projects to “pyramid” several genes for resistance to Ug99 to increase the longevity of the resistance. Pyramids containing 3 and 4 resistance genes have been crossed and backcrossed onto elite spring and winter wheat germplasm at ORDC and Lethbridge Research & Development Centre (LRDC). Pyramids have been distributed freely to other spring wheat breeding programs.

Some of the pyramids have been combined with genes for resistance to FHB and leaf rust to create packages of enhanced germplasm containing resistance to all these diseases. All disease resistance genes involved are suitably marked with user-friendly markers to facilitate marker assisted selection in breeding programs.

Leaf rust is also a significant problem in Ontario. Currently there appears to be no research being conducted on producing resistant germplasm. Lr34 is being incorporated into breeding material through the pyramids and Lr34 is being combined with Lr71 that was derived from T. monococcum. In the last few years stripe rust has been spreading in Canada and even Ontario. By testing some of our mapping populations in Kenya, we discovered that they also carried resistance to stripe rust. Mapping populations have now been screened in Kenya and Lethbridge. The next step was the mapping of these genes.

Results

Objective 1:

Three main doubled haploid mapping populations were produced for mapping of resistance genes derived from:

  • GO1, Maringa – Ae. cylindrica
  • GO2, T. timopheevii – Ae. cylindrica
  • GO3, T. miguschovae

Populations were phenotyped for FHB in Ontario, for Ug99 in Kenya, and stripe rust in Kenya and Lethbridge. Genotyping was carried out by DOW AgriSciences with a 90K chips (SNP). In Ae. cylindrica the FHB QTL was located on chromosome 2D; in T. timopheevii the FHB QTL was located on chromosome 3B and stripe rust resistance on chromosome 1B; in T. miguschovae the QTLs for FHB resistance were located on chromosomes 2D and 5A.

In a separate undertaking, the FHB resistance introgressed from T. monococcum was mapped on chromosome 5A using the M321 x Superb DH mapping population and SNP markers (from NRC Saskatoon).

Crosses were made using selected lines out of mapping populations to begin the process of pyramiding the unique FHB resistance QTL. The SNP markers will need to be converted to KASP markers for the process of Marker Assisted Selection. The pyramids will eventually enter spring and winter wheat breeding programs, leading to commercial cultivars protected by these genes.

Objective 2:

It is well known that a single resistance gene in a commercial cultivar may only last 3, 5, and, if lucky, up to 10 years before the pathogen mutates and defeats the resistance gene. Using DH technology and screening for available SSR-marked Ug99 resistance genes we chose to produce a series of pyramids containing up to 4 Ug99 resistance genes.

A total of 36 different pyramids / combinations were produced containing various combinations of 2, 3, and 4 resistance genes. Some pyramids also contain Lr34, Fhb1 and Bt10 which is linked to Sr Cad.

A total of 48 crosses of Ug99 resistant pyramids have been made onto 5 elite cultivars of the ORDC spring wheat program. Some pyramids had up to 4 resistance genes. In some cases, BC2 progeny were produced and forwarded to the breeder.

Similarly, some of the pyramids were crossed onto 8 elite winter wheat cultivars and F1 seed forwarded to breeding programs at Ottawa and Lethbridge. Pyramids have been shared with breeding and genetics programs nationally and internationally.

Objective 3:

The leaf rust resistance in line M321 with the T. monococcum introgression was mapped by NRC to chromosome 1B using SNP markers on the M321 x Superb DH population; phenotyping done by Brent McCallum.

The leaf rust resistance gene Lr71 introgressed from T. monococcum was crossed onto Lr34 to begin a gene pyramiding exercise. Gene banks at CIMMYT and AAFC Saskatoon have requested the above genetic stock for their holdings.

External Funding Partners:

This research activity was part of the National Wheat Improvement Program Cluster led by the Western Grains Research Foundation (WGRF).

Funding for this project was provided in part by Agriculture and Agri-Food Canada through the Growing Forward 2 (GF2) AgriInnovation Program and in part by Canadian Field Crop Research Alliance (CFCRA) members. Grain Farmers of Ontario is a founding member of the CFCRA.

Project Related Publications:

Fedak, G. 2015. Alien Introgressions from wild Triticum species T. monocuccum, T. Urartu, T. turgidum, T. dicoccum, T. dicoccoides, T. carthluim, T. araraticum, T. timopheevii and T. miguschovae. In: Monár-Láang, M., Ceoloni C., Dolezel, J., editors. Alien Introgression in Wheat, Cytogenetics Molecular Biology and Genomics. Springer International Publishing. Chapter 8.

Fedak, G. 2017. Potential of wide crosses to improve the resistance to vomotoxin accumulation in wheat following infection by Fusarium head blight. In: Wanyera, R. and Owuocle, J., editors. Wheat Improvement, Management and Utilization. Intech-Publisher International Symposium. P. 59-75.

Malihipour, A., Gilbert, J., Fedak, G., Brule Babel, A. L., and Cao W. 2016. Characterization of agronomic traits in a population of wheat derived from Triticum timopheevii and their association with Fusarium head blight. European Journal of Plant pathology. P.1-13.

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