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

Abstract To improve brown planthopper ( Nilaparvata lugens Stål; 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 ( BC 3 ) 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 + Bph15 ≥ Bph3 + Bph15 ≥ Bph3 +Bph14 ≥ Bph14 + Bph15 ≥ Bph3 ≥ Bph15 ≥ Bph14 > 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.