Introgression of bacterial blight (BB) resistance genes Xa7 and Xa21 into popular restorer line and their hybrids by molecular marker-assisted backcross (MABC) selection scheme

摘要

Yihui1577 is an elite restorer line widely used in hybrid rice production in China, however, both the restorer and their derived hybrids are susceptible to bacterial blight (BB) caused by?Xathomonas oryzae?pv. oryzae?(Xoo). In order to overcome this problem, we had introgressed two resistant genes?Xa7?and?Xa21?into Yihui1577 by marker-assisted backcross (MABC) with foreground selection scheme to speed up the process. Six breeding lines with different BB resistance genes: HH1202 (Xa7), HH1203 (Xa7), HH1204 (Xa21), HH1205 (Xa21), HH1206 (Xa7+Xa21) and HH1207 (Xa7+Xa21) were selected and crossed with four CMS and one TGMS lines. Seven most virulent and prevalent?Xoo?strains (PXO61, PXO99, ZHE173, GD1358, FuJ, YN24 and HeN11) from the Philippines and different provinces of China were inoculated for evaluating the BB-resistance of the selected lines and their derived hybrids. The results reveal that the two lines and their derived hybrids with single resistance gene?Xa7?were resistant against six of the seven?Xoo?strains, except for PXO99. The lines with single resistance gene?Xa21?were only susceptible to the?Xoostrain FuJ, but some of their derived hybrids were susceptible to the?Xoo?strains FuJ and GD1358. Interestingly, the pyramiding lines carrying the two resistance genesXa7?and?Xa21?and also their derived hybrids were resistant against all the seven?Xoostrains. The data of agronomic and grain quality characteristics demonstrated that the selected lines were similar to that of the recurrent parent Yihui1577. Corrective measures taken by way of introgression of BB-resistance genes:?Xa7?and?Xa21?into the popular restorer line, Yihui1577 through MABC approach for enhancing the BB-resistance level was effective and timely.