This research is dealing with identification of SSR markers linked to and chromosomal assigment of the two effective brown planthopper (BPH) resistance genes bph4 and Bph6 for the further use in rice breeding.
Two mapping populations were developed from the crosses of TN1xDG5 and TN1xGC9, where DG5 and GC9 were Babawee- and Swarnalata-derived breeding lines, respectively, in which the genetic segregation analyses confirmed that DG5 and GC9 possessed recessive (bph4) and dominant (Bph6) resistance genes, respectively. Phenotyping analyses were carried out in F3 generations, based on that each of F2 individuals were judged for homozygous resistance, homozygous susceptibility, or heterozygosity. Bulk segregant SSR analyses were performed using 4-5 SSR polymorphic loci per chromosome. As results, only the SSR loci of the chromosome 4 seemed to co-segregate with the bph4 or Bph6 genes. Afterwards, more than a hundred of F2 individual plants of each mapping population were surveyed with SSR markers of the chromosome 4. Then linkage analyses were accomplished using the MapMaker programme. It showed that the both bph4 and Bph6 loci were located on the chromosome 4, where the bph4 was close to the marker RM261 and the Bph6 was located between the markers RM119 and RM317. Identification of closer markers and detailed mapping of the resistance genes are underway.
Luu Thi Ngoc Huyen, Vu Duc Quang
Thieu Van Duong
Collegue of Cantho