Marker-assisted transfer of PinaD1a gene to develop soft grain wheat cultivars.

Grain softness has been a major trait of interest in wheat because of its role in producing flour suitable for making high-quality biscuits, cookies, cakes and some other products. In the present study, marker-assisted backcross breeding scheme was deployed to develop advanced wheat lines with soft grains. The Australian soft-grained variety Barham was used as the donor parent to transfer the puroindoline grain softness gene Pina-D1a to the Indian variety, DBW14, which is hard grained and has PinaD1bPinbD1a genes. Foreground selection with allele-specific PCR-based primer for Pina-D1a (positive selection) was used to identify heterozygous BC(1)F(1) plants. Background selection with 173 polymorphic SSR primers covering all the 21 chromosomes was also carried out, in the foreground-selected BC(1)F(1) plants. BC(1)F(2) plants were selected by ascertaining the presence of Pina-D1a (positive selection) and absence of Pina-D1b (negative selection). Using the approach of positive, negative and background selection with molecular markers, 15 BC(1)F(2) and 31 BC(2)F(1) plants were finally selected. The 15 BC(1)F(2) plants were selfed and the 31 BC(2)F(1) plants were further backcrossed and selfed to raise BC(3)F(1) and BC(2)F(2) progenies, respectively. A part of the BC(2)F(2) seed of each of the 31 plants was analyzed for grain hardness index (GHI) with single-kernel characterization system. The GHI varied from 12.1 to 37.1 in the seeds borne on the 31 BC(2)F(1) plants. The reasons for this variation and further course of action are discussed.