Development of near isogenic lines for grain softness through marker assisted backcross breeding in wheat

The genes for grain softness and rust resistance were transferred from a soft grained Australian wheat variety (Barham) to a hard grained Indian wheat variety (DBW14) through marker assisted back cross breeding. Backcrosses were made with recurrent parent in the BC1F1 plants that were found positive for markers of Pina-D1a, Pina-D1b and Lr37b genes. The BC2F1 plants were further screened and those that possessed the PinaD1a and Lr37b alleles were advanced up to BC2F4 with continued marker assisted selection and field screening. 48 SSR markers that were heterozygous in the BC1F1 plants were used for background selection in three BC2F1 plants derived from three respective BC1F1s. Further generations were screened for morphological traits in the field and 16 BC2F4 lines were finally selected through combined field and marker screening. These 16 near isogenic lines (NILs) had lower grain hardness index (13.86–47.13) than the recurrent parent DBW 14 (81.76) and displayed more than 95% of the recurrent parent genome. 12 of the NILs had significantly higher grain yield than DBW 14. Combined foreground and background selection strategy coupled with field screening, was thus, found to be an effective strategy for transferring grain softness in wheat.