Genetics of fertility restoration of ‘WA’ based cytoplasmic male sterility system in rice (Oryza sativa L.) using basmati restorer lines

Hybrid technology in basmati rice (Oryza sativa L.) is expected to make a quantum increase in production and boost the export of the country. The success in development of basmati hybrids largely depends on availability of effective restorers and precise basic knowledge on the genetics of fertility restoration of such lines. Study using five diverse restorers and Pusa 3A - a ‘WA’ type cytoplasmic male sterile (CMS) line in basmati background, revealed the fertility restoration to be governed by two major genes with epistatic interactions that differed from cross to cross. Restorers PRR 78 and PRR 73 when crossed with Pusa 3A - segregated in the ratio of 9:3:4 and 1:1:2 in F₂ and BC₁ generations, respectively for pollen and spikelet fertility indicating two major genes with recessive epistasis involved in fertility restoration. Crosses Pusa 3A/PRR 72 and Pusa 3A/IR 42266 showed a segregation ratio of 9:6:1 and 1:2:1 in F₂ and BC ₁ generations, respectively, indicating two major genes governing fertility restoration showing epistasis with incomplete dominance. Pusa 3A/IR 48749 gave segregation ratio of 12:3:1 in F₂ and 2:1:1 in BC ₁ generation showing digenic dominant epistatic interaction.