Performance Story: Genetics and Improvement of Earliness in Canadian Spring Wheat
Spring wheat remains the most important crop in western Canada, with high-quality Canadian western red spring wheat accounting for about two-thirds of the total. Because of the short growing season, yields of spring wheat are generally lower than those obtained with winter wheat. In addition, a great deal of bread wheat grown in the northern regions of the Prairie Provinces is downgraded because it becomes frost-damaged before full maturity. Later maturing wheat can also be more difficult to harvest. Hence, early maturity is a desired trait to be incorporated (without compromising high yield and quality) into Canadian spring wheat.
The objectives of this project were to better understand the genetics of earliness in Canadian spring wheat, to develop wheat germplasm with a new combination of earliness related genes, to develop mapping populations for future genetic studies, to complete statistical analyses of previously funded studies, and to train highly skilled manpower in wheat breeding and genetics.
We screened 99 previously uncharacterized Canadian spring wheat cultivars/lines for presence/absence of earliness-related genes and found interesting combinations. This provides valuable information to wheat breeders and researchers in future research and development.
We made seven crosses for combining three earliness-related genes from a Canadian wheat background. We are yet to confirm the presence of the three gene combinations using molecular markers due to laboratory closure in 2020 following the Covid‐19 pandemic. The combination of three earliness genes is expected to result in early maturing wheat. This genetic material will also be useful for future earliness studies and some will be tested in yield trials to test their potential to become cultivars.
We also made 11 crosses between early and late maturing wheat cultivars/lines (AAC Wheatland, AAC Starbuck, AAC Tenacious, AAC Viewfield, AAC Wheatland, AC Splendor, Carberry, Go Early, Parata, Park, and PT251) and developed mapping populations that will help to further understand the genetic basis of earliness in Canadian spring wheat and identify DNA markers for future marker-assisted selection. Some lines from these crosses will become early maturing cultivars.
We evaluated a biparental mapping population of 208 recombinant inbred lines (RILs)derived from the cross Peace × Carberry for earliness in the field in 2016‐2020 and found a total of 23 QTLs associated with three earliness traits, including 8 for heading time, 6 for anthesis time and 9 for maturity time.
We had one cultivar (BW5065) developed from the Peace × Carberry mapping population accepted for registration at the PGDC meetings in 2021.
We evaluated a genomewide association mapping panel of about 200 spring wheat lines/cultivars in 2018‐2020 for earliness, agronomic traits, and reaction to diseases, genotyped the panel with the wheat 90K iSelect array, and conducted data analyses. We found a total of 64 markers statistically associated with days to heading and maturity recorded under conventional and organic management systems. However, the most important genomic region was on chromosome 5A, which harboured 12 protein-coding candidate genes, including the well know Vrn‐A1 (TraesCS5A02G391700) gene.
In previous studies, we mapped and characterized genes and QTLs associated with earliness in four hard red spring wheat recombinant inbred line (RIL) populations but the results were scattered in population‐specific genetic maps, which is hard to exploit efficiently in breeding programs. As part of this project, we mapped and characterized QTL associated with anthesis, heading and maturity across four biparental mapping populations (Peace x Carberry, Peace x CDC Stanley, Attila x CDC Go, and Cutler x AC Barrie) using the International Wheat Genome Sequencing Consortium (IWGSC) RefSeq v2.0 physical map. We identified a total of 44 population‐specific QTL associated with heading (11), flowering (10), and maturity (23).
The information generated and wheat materials developed in this project provide a useful resource for wheat researchers and breeders in future research and development. Some of the early lines, after testing for yield and other traits and becoming cultivars, will offer wheat producers the choice of growing early maturing wheat cultivars.
We also trained highly skilled manpower that will strengthen future wheat breeding and genetics activities.