Development of pyramided lines carrying brown planthopper resistance genes in the genetic background of Indica Group rice (Oryza sativa L.) variety ‘IR64’

抄録

The development of resistant rice (Oryza sativa L.) varieties is a key strategy for the eco-friendly control of brown planthopper (BPH: Nilaparvata lugens Stål). However, BPH outbreaks occur frequently owing to the evolution of virulent strains in the field and the rapid breakdown of monogenic resistance to BPH. Therefore, to enhance BPH resistance and gauge the effectiveness of gene pyramiding against strongly virulent BPH, we developed pyramided lines (PYLs) in the genetic background of ‘IR64’ carrying BPH resistance genes. We developed six IR64-PYLs (BPH3 + BPH17, BPH32 + BPH17, BPH32 + BPH20, BPH3 + BPH17-ptb, BPH20 + BPH3, and BPH17-ptb + BPH32) through marker-assisted selection. To assess the resistance of the IR64-PYLs, we conducted antibiosis test, honeydew test, and modified seedbox screening test (MSST) using strongly virulent BPH populations. The level of BPH resistance increased in all six IR64-PYLs compared to ‍both ‘IR64’ and the corresponding NILs in MSST. Among them, IR64-BPH3 + BPH17 and IR64-BPH32 + BPH17 exhibited the highest resistance to BPH. However, the resistance level of most IR64-PYLs was not significantly higher than that of the corresponding NILs in antibiosis test. Thus, these PYLs could serve as a valuable resource for breeding programs aimed at improving resistance to virulent strains of BPH and enhancing their durability.