Development of KASP Markers for Introgression of the Hessian Fly-Resistance Gene, H33 into Wheat Cultivars

Host-plant resistance is an effective and economical method of minimizing Hessian fly (Mayetiola destructor) damage to wheat (Triticum aestivum, L).  A Hessian fly-resistance gene, H33, highly effective against all virulent fly biotypes and populations tested, was previously introgressed from durum into common wheat and genetically mapped to the distal end of chromosome 3AS using simple sequence repeat (SSR) markers. However, the closest flanking SSR markers for H33 reside 7.4 and 25.1 cM from the gene. To narrow the H33 interval, we employed bulked-segregant analysis with the next generation genotyping-by-sequencing (GBS) technology and identified 5 GBS-SNP (single nucleotide polymorphism) markers targeted to the H33 region of chromosome 3AS. The GBS-SNP markers designated as purdue ars single nucleotide polymorphic (parsnp) markers were converted into cost-effective Kompetitive Allele-Specific PCR (KASP) assay markers and used to screen a mapping population of 128 F_2:3 families derived from resistant and susceptible nearly isogenic wheat lines. Linkage maps localized two parsnp markers near the H33 locus within the 7.4 cM region, while three parsnp markers were localized to the unmarked 25.1 cM region.  In addition, we also show that restriction digestion of the two flanking parsnp markers can be used as an alternate to the KASP assay to detect polymorphism between resistant and susceptible plants. Development of these cost-effective parsnp markers provides both low- and high-throughput alternatives for introgressing H33 into wheat cultivars while minimizing any linkage drag associated with durum regions of chromosome 3AS.