Identification of KASP markers and putative genes for herbicide (metribuzin) tolerance in common wheat (Triticum aestivum L.).

Weeds significantly threaten wheat production by competing for essential resources and facilitating the spread of pests and diseases. The use of herbicides is the most common approach for controlling weeds. There is an urgent need of mining molecular markers and key genes for herbicide tolerance to accelerate marker assisted/molecular design breeding of new wheat cultivars with improved tolerance to herbicides. However, it is very difficult and costly to mine molecular markers and key genes for complex quantitative trait like herbicide tolerance, especially in wheat, a typical allopolyploid with large complex genome. Two practical KASP markers were developed with 77.6%-87.9% conformity between genotype and phenotype of the tolerance to metribuzin (a commonly used herbicide) in wheat with targeted optimization of a conventional BSA-based approach named SRV. The two SNPs corresponding to these two KASP markers are closely linked with two independent genes on chromosome 2AS and both encoding for IgA (Immunoglobulin A) FC receptor protein. More interestingly, another 9 genes having the same annotation of IgA FC receptor were detected within 1 Mbp distance of the two SNPs, forming a gene cluster. This study has provided valuable insights into the development of KASP markers for metribuzin tolerance in wheat and has identified putative genes that may be involved in herbicide resistance metabolic regulation.