Incorporation of a null allele of Kunitz trypsin inhibitor through molecular backcross breeding in soybean [Glycine max (L.) Merrill.]

Abstract

Trypsin inhibitors being anti-nutritional, are a major deterrent in the utilization of soybean as a human food and animal feed. For the genetic elimination of Kunitz trypsin inhibitor, a dysfunctional null allele (titi) of seed-specific KTI3 gene was transferred from (NRC 101 and NRC 102) to three rust-resistant varieties, Phule Agrani, P. Sangam, and P. Kimya. Null allele-specific titi-420bp and linked Satt409-170bp markers could identify two F2, single F3 and F4 each, eleven BC1F2, ten BC1F3 and three BC2F2 titi plants with titi genotype among the 131 plants studied. In biochemical assay, the trypsin inhibitor activity in seeds of these plants ranged from 4.03 to 9.67 mg/g-1. Based on both molecular and biochemical studies, it could be concluded that these 28plants were free of Kunitz trypsin inhibitor (kti null).