Identification of a RAPD marker linked to a brown planthopper resistance gene in rice

We report the tagging of a brown planthopper (BPH) resistance gene (Bph-1) in rice using RAPD and RFLP markers. The Korean rice variety 'Gayabyeo' has dominant duplicate genes including Bph-1 conferring resistance to biotype 1 of BPH. Bulked segregant RAPD analysis was employed for rapid identificat ion of DNA markers linked to resistance genes. For tagging these two genes, an F-2/F-3 population from a 'Gayabyeo' x 'Nagdongbyeo' cross was develope d and evaluated for BPH resistance. Three bulked DNAs from two groups of ho mozygous BPH resistant (each for Bph-1 and the other unknown gene) and homo zygous susceptible F-2 plants were analyzed by RAPD using 140 random oligom ers. One primer, OPD-7 yielded a 700-bp fragment that was present in Gayaby eo and resistant F-2 plants (homozygous for Bph-1 locus) but absent in Nagd ongbyeo and susceptible F-2 plants. Cosegregation of this marker with Bph-1 was verified using an F-2 population segregating for Bph-1. Chromosomal re gions surrounding the Bph-1 were examined with additional RFLP and microsat ellite markers on chromosome 12 to define the location of the RAPD marker a nd Bph-1. Use of this RAPD marker could facilitate early selection of resis tant lines for BPH.