Comparison of Shoot Fly Resistance QTLs in Sorghum Introgression Lines Using SNP Genotyping

Abstract

Shoot fly is a major pest in sorghum that causes significant annual yield loss. Use of pesticide to control this pest is an expensive and environmentally unsafe approach. Present study investigated the host plant resistance mechanism to develop shoot fly resistance (SFR) lines through transfer of shoot fly resistance QTLs (glossiness, trichome density, ovipositional non-preference) using SSR marker assisted backcrossing. Genomic regions for SFR showed four QTLs on SBI 01, SBI 07, SBI 05 and SBI 10 contributing up to 11.5%, 18.3%, 14% and 14.7% phenotypic variation. But QTLs on SBI 05 and SBI 10 for glossiness and trichome density are the major QTLs for which 10 SNPs have been designed. In earlier studies, three QTL regions associated with shoot fly resistance were successfully introgressed into elite cultivar SPV 1411 (Parbhani Moti) and a B line ICSB29004 using donors viz. J2658 (SBI01), J2614 (SBI10), and J2714 (SBI07) (which are derivatives of BTx 623). Phenotyping of introgression lines (ILs) led to the identification of resistant lines for each QTL region present on chromosome SBI-01, SBI-07 and SBI-10. Hence, in this study we have analysed the above developed ILs using single-nucleotide polymorphism (SNP) markers tightly linked to shoot fly resistant QTLs. The results showed that introgression lines with QTL present on chromosome SBI-10 were segregating for favorable alleles for leaf glossiness and for trichome density in homozygous condition. Other introgression lines with QTLs on chromosome SBI-01 and SBI-07 for component traits - oviposition non-preference, seedling vigor are segregated for glossiness trait also thus showing the transfer of non-targeted region, which in this case proved beneficial for SFR. This study showed that these SNPs can be used to analyze introgression lines and can be used as genomic markers for early generation selection of shoot fly resistance lines.