High-resolution mapping of a gene conferring strong antibiosis to brown planthopper and developing resistant near-isogenic lines in 9311 background

The brown planthopper (BPH), Nilaparvata lugens Stål, is one of the most destructive pests to the rice production in the world. Thus, there is an urgency to identify new resistant genes for breeding. AC-1613 is an indica variety that has been reported to confer broad-spectrum resistance to BPH. In the present study, we found that AC-1613 exhibited strong antibiosis towards BPH insects. The body weight was significantly decreased when the insects fed on AC-1613 plants. By using BPH weight gain as an index of phenotyping, a novel dominant locus for resistance to BPH, designed as Bph30, was identified and its near-isogenic line (NIL) in 9311 background was developed. The F₂ population derived from a cross between AC-1613 and 9311 was used for mapping the gene. Through QTL scan, we located the gene on the short arm of chromosome 4 between RM16278 and RM16425, which explained 42.7% of the phenotypic variance (PEV) of BPH resistance in the F₂ population. The gene was finally located in a region flanking by simple sequence repeat (SSR) markers SSR-28 and SSR-69 through high-resolution mapping, the distance between the two markers in Nipponbare genome is 37.5 kb. In addition, SSR markers RM16294 and RM16299 tightly linked to Bph30 were applied effectively in introgressing Bph30 into elite rice cultivars. The developed NILs showed a strong antibiosis and high resistance to BPH.