Identification of novel candidate of brown planthopper resistance gene Bph44 in rice (Oryza sativa L.).

The brown planthopper (BPH, Nilaparvata lugens Stål) is still considered a major threat to rice farmers. Exploring novel resistance genes that relate to the BPH population in the targeted rice-growing area might be a suitable solution. We identified and mapped the gene locus using 175 lines of F_2:3 populations derived from Balamawee × PD601. Genomic analysis was then used to identify the candidate gene governing the resistance toward BPH. We discovered a novel genetic locus for BPH resistance in the long arm of chromosome 4 linked to markers Q31 and RM17007 at 4.76 and 5.42 cM, respectively, with total phenotypic variation reaching 52.21% at LOD 29.68. The tolerance mechanism influences the nature of this resistance, as shown by the Functional Plant Loss Index. The resistance level, mechanism of resistance, and physical mapping reveal that the resistance genes in this study differ from the previous study, therefore, we propose this novel gene as Bph44.