Segregation of molecular markers associated with Bph3 gene in BC₅F₂ population derived from Ciherang rice variety as the recipient parent

Abstract

Brown planthopper (BPH), an important insect pest of rice, can cause severe damage and significant yield loss. An efficient and environmentally friendly method to control this pest is by planting resistant varieties. The brown planthopper resistance gene Bph3 from Rathu Heenati variety is closely linked to the Waxy gene that regulates amylose synthesis, the primary determinant of rice eating and cooking quality. The purposes of this study were to analyze the segregation ratio of SSR markers associated with Bph3 gene and to identify individual plants carrying homozygous allele for Bph3 gene in a BC5F2 population derived from a backcross that used Ciherang as the recurrent recipient parent. Analyses using RM589, RM586, and RM588 markers linked to Bph3 gene and RM190 marker linked to the Waxy gene indicated that the ratio of genotype segregation for each marker related to Bph3 gene did not deviate from the expected ratio with the χ 2 value was 0.956, 0.587, and 1.467 for RM589, RM586, and RM588, respectively (χ2 table = 5.991, α=0,05). All individual plants had a homozygous allele from Ciherang for Waxy gene based on the RM190 marker. As many as 25 individual plants which have homozygous Bph3 allele from Rathu Heenati and homozygous Waxy allele from Ciherang can be further developed as promising BPH-resistant rice varieties with eating and cooking quality similar to Ciherang.