Development of elite restoring lines by integrating blast resistance and low amylose content using MAS

Blast resistance and grain quality are major problems in hybrid rice production in China. In this study, two resistance （R） genes, Pi46 and Pita, along with the gene Wxb, which mainly affects rice endosperm amylose content （AC）, were introgressed into an elite indica restoring line, R8166, which has little blast resistance and poor grain quality through marker-assisted selection （MAS）. Eight improved lines were found to have recurrent genome recovery ratios ranging from 88.68 to 96.23%. Two improved lines, R163 and R167, were selected for subsequent studies. R167, which has the highest recovery ratio （96.23%）, showed no significant differences in multiple agronomic traits. In contrast, R163 with the lowest recovery ratio （88.68%） exhibited significant differences in heading date and yield per plant compared with the recurrent parent. At two developmental stages, R163 and R167 had greatly enhanced resistance to blast over the recurrent parent. Similar trends were also observed for agronomic traits and blast resistance in R163- and R167-derived hybrids when compared with the counterparts from R8166. In addition, R163, R167, and their derived hybrids significantly improved the grain quality traits, including amylose content （AC）, gel consistency （GC）, chalky grain rate （CGR）, and degree of endosperm chalkiness （DEC）. It confirmed the success of efficiently developing elite restoring lines using MAS in this study.