Genetic Analysis And Molecular Mapping Of The Brown Planthopper Resistance Gene Derived From Guangxi Common Wild Rice Species(Oryza Rujipogon Griff.)

The brown planthopper (Nilaparvata lugens Stal, BPH) is one of the most destructive insect pests of rice plant and has caused serious loss during the rice production. Exploring resistance genes from diverse rice germplasms and incorporating them into cultivated varieties are very critical for controlling this insect. Newly identified rice line 08BPH327 is derived from the hybrid offspring of BPH-resistance Guangxi common wild rice species and variety Xixiangruo. We evaluated its BPH-resistance level and resistance mechanism through seedling and adult stage insect resistance tests, BPH host choice test, survival rates detection, BPH population growth rate and honeydew excretion quantity tests. As a result, we found that new resistance rice line 08BPH327 had a high resistance level in the seedling and adult stage resistance tests. After that, it showed significantly antixenotic and antibiotic effects on the BPH insect comparing with the susceptible rice line 9311. Two F2 population,186S/08BPH327 and 9311/08BPH327, were constructed to map the BPH-resistance gene. Subsequently, one dominant major resistance gene was identified through the genetic analysis of the BPH-resistance scores of F2 population 186S/08BPH327. Moreover, in analysis of the F2 population, the resistance gene was located on the long arm of chromosome 4 between the SSR markers RM16670 and RM16717. The largest LOD score was 19.8 and explained 44.5% of the phenotypic variance of BPH resistance in F2 population. About 6000 BC1F2 and F3 individuals have been screened and 79 recombinants between RM16670 and YM2 were obtained. Based on the recombinants, the resistance gene was further mapped precisely to a region flanked by the markers YM61 and YM54 between which the physical distance are about 68kb in Nipponbare genome. At the same time, the resistance gene was introgessed into the rice varieties 9311, Nipponbare, Baimao, and BaiR54 by crossing and backcrossing to construct the near isogenic lines (NILs). The finely gene mapping and NILs construction would directly offer the BPH-resistance rice lines and tightly linked markers for the rice insect-resistance breeding and molecular marker-assisted selection. Furthermore, it would benefit for the map-based gene clone and insect resistance mechanism conferred by the resistance gene.