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Abstract

Exploitation of the higher degree of heterosis manifested in inter sub-specific (indica and indica/japonica) derivatives is one of the current trends in hybrid rice breeding. The success in developing indica/japonica hybrids using new plant type restorers developed from indica/japonica derivatives largely depends on the availability of effective restorers and knowledge of the genetics of fertility restoration of such derivative lines. A study using three indica

Genetic effects on the number of spikelets per panicle and fertility restoration in three-line hybrid rice breeding system

“…This ratio was accepted for two genes with complementary epistasis (at least one dominant allele from each of the two genes needed for expression of the final phenotype). Similar results were demonstrated using three indica/japonica restorers and three WA-type CMS lines showing that two or three major genes controlled fertility restoration with epistasis interactions differing from cross to cross [38]. Study results also indicated different types of gene interactions, such as recessive epistasis, semi-epistasis [39], epistasis with incomplete dominance [40], and epistasis with complete dominance [41].…”

A Study on Comparative Fertility Restoration in A2 and A4 Cytoplasms and Its Implication in Breeding Hybrid Pigeonpea [Cajanus cajan (L.) Millspaugh]

“…The variable expression of fertility restoration can be attributed to different genetic backgrounds of the F 1 plants, arising from male parents of different genetic constitution. Alternatively, differences observed in segregation patterns also could be due to the presence of some modifier genes that influence the process of penetrance and expressivity of the fertility-restoring genes [14]. On the contrary, the same pollinator (restorer) may also produce variable results if crossed with different A 4 CMS lines [7].…”