Application of marker-assisted backcross to introgress Bph3, Bph14 and Bph15 into an elite indica rice variety for improving its resistance to brown planthopper

To improve brown planthopper (Nilaparvata lugens Stal; BPH) resistance of an elite indica cultivar of South China, Hemeizhan (HMZ), we applied marker-assisted backcross (MABC) to incorporate three BPH-resistance genes (Bph3, Bph14 and Bph15) into the genetic background of HMZ. In the third backcross (BC3) generation, we obtained near-isogenic lines (Bph3-NIL, Bph14-NIL, Bph15-NIL and Bph14+Bph15-NIL) with more than 96% recovery of recurrent parent genome, and pyramided lines (Bph3+Bph14-PYL, Bph3+Bph15-PYL and Bph3+Bph14+Bph15-PYL) with more than 89% recovery of recurrent parent genome. These lines showed stronger resistance against BPH than HMZ at seedling and booting stages. The rank of resistance gene effect was Bph3+Bph14+Bph15Bph3+Bph15Bph3+Bph14Bph14+Bph15Bph3Bph15Bph14>none. Compared with HMZ, only Bph3+Bph14+Bph15-PYL had a significant difference in yield per plant, and the lines carrying Bph3 had higher amylose contents, indicating that Bph3 was tightly linked to Wx(a) allele. These improved lines are good intermediate sources of broad-spectrum and durable BPH resistance to improve other indica cultivars. Our results demonstrate that MABC is a very efficient approach to improve BPH resistance of elite rice cultivar.