Selection tools for varieties with increased disease resistance Objective 4
We aim to combine phenotyping and genotyping approaches to identify resistance genes and markers that can be used in the development and release of soybean varieties resistant to the main pathogens/pest in Canada.
Our limited knowledge regarding the genetic identity of the pathotypes of P. sojae and H. glycines affecting soybean crops in Canada has conversely hampered our ability to develop resistant varieties. In the same manner, the deployment of soybean germplasm resistant or tolerant to S. sclerotiorum has been restrained by a poor understanding of genetic loci contributing to resistance. Through a better knowledge of the identity of the pathogens, extensive phenotyping relying on precise bioassays developed by members of our team, combined with extensive genotyping of sources of resistance in soybean, we will have all the tools to develop new varieties specifically addressing the needs of growers.
The following sub-objectives will be instrumental to reach the main goal.
Obj.4.1 Phytophthora sojae (PRR)
We propose to take advantage of this novel, sensitive and accurate bioassay to identify soybean lines exhibiting a high degree of horizontal resistance, to perform QTL mapping for horizontal resistance to P. sojae and to develop SNP markers associated with horizontal resistance to P. sojae.
Obj.4.2 Heterodera glycines (SCN)
The overall objective is to breed for SCN resistant soybean varieties adapted to Canadian environments of maturity 000 to I. In order to do so, we aim to identify and validate new sources of resistance that will be resistant to the SCN populations representative of the major SCN populations found in Canada, to develop breeding populations and advanced lines by performing crosses between agronomically superior early maturity lines and the best sources of resistance, and to identify molecular markers linked to the resistance in these newly identified sources of resistance and incorporate these molecular marker selection tools in the breeding programs
Obj.4.3 Sclerotinia sclerotiorum
We propose to pursue both these lines of work in view of validating these candidates and developing markers for validated QTLs/genes to validate candidate QTLs for SSR resistance in biparental populations, to validate candidate genes whose overexpression is associated with resistance and to design allele-specific markers for validated SSR resistance QTLs/genes.
1) Candidate QTLs and DNA markers for horizontal P. sojae resistance
2) Candidate QTLs and DNA markers for H. glycines resistance
3) Candidate QTLs and DNA markers for S. sclerotiorum resistance