Genetics of fertility restoration in ‘WA’ cytoplasmic male sterility in rice (Oryza sativa L.)

Abstract

A study using three cytoplasmic male sterile lines (IR-68897A, IR-68888A and IR-58025A) and ten restorers revealed that two or three major genes govern the fertility restoration, with epistatic interaction that differed from cross to cross. The crosses, IR-68897A x URG-22, IR-68888A x URG-51, IR-68888A x URG-84, IR-58025A x Sarjoo-52 and IR-58025A x URG-48 showed segregation ratio of 9:6:1 in F2 and 1:2:1 in BC1 generation, for pollen fertility indicating that the genotypes viz. Sarjoo-52, URG-22, URG-51, URG-48 and URG-84 carry two independent segregating genes with additive type of gene action, the effect of one of the two gene in restoring fertility appeared to be stronger than the other. The crosses IR-68888A x BPT-5204, IR-58025A x Pant-12 and IR-58025A x URG-77 segregated in ratio of 9:3:4 and 1:1:2 in F2 and BC1 population respectively, indicating the presence of two independently segregating dominant genes showing recessive epistatic interaction of the fertility restoring genes in the genotypes, BPT-5204, Pant-12 and URG-77. The crosses IR-68897A x Jaya and IR-68897A x Shivani given segregation behavior of 12:3:1 in F2 progeny and 2:1:1 genetic ratio in test cross progeny suggesting the presence of two dominant genes with dominance epistasis in the fertility restoring genes in the genotypes Jaya and Shivani.