Marker-assisted stacking of null Kunitz trypsin inhibitor and off-flavour generating lipoxygenase-2 in soybean

Abstract

AbstractSoybean varieties genetically free from Kunitz trypsin inhibitor (KTI) and lipoxygenase-2 (Lox2) are desirable to increase human consumption, as the former is an antinutritional factor that affects protein digestibility while the latter is a principal contributor to off-flavour. In the present investigation, soybean genotypes free from both these undesirable components were developed by introgression of null allele of Lox2 from NRC109 (lox2lox2) into two KTI-free soybean genotypes derived from genotypes JS97-52 and NRC7. Foreground selection of plants in F1, F2, BC1F1, BC1F2, BC2F1 and BC2F2 generations developed from two cross combinations i.e. NRC7-derived KTI-free genotype (N7KTIF)×NRC109 (parental combination 1) and JS97-52 derived KTI free genotype (JKTIF)×NRC109 (parental combination 2) was performed using null allele specific markers and tightly linked simple sequence repeat (SSR) markers for both KTI and Lox2 genes for the identification of homozygous recessive (titilox2lox2) plants. Background selection was performed using 239 and 241 polymorphic SSR markers across the genome. This resulted in the development of 9 and 13 soybean lines stacked for null alleles of both KTI and Lox2 (titilox2lox2) exhibiting recurrent parent genome content more than 97 and 96%, respectively. Days-to-flowering, days-to-maturity, 100-seed weight and yield per plant of the stacked lines developed from both the parental combinations were at par with the respective recurrent parents.