Molecular Marker and Test Cross Information Aid Selective Advancement of F4 Generation of CB174R/Azucena: An inter Sub-specific Cross in Rice for Restorer Development

The present investigation was aimed to develop restorer lines for three-line hybrid rice using indica/tropical japonica derivatives to exploit the inter sub-specific heterosis. From 75 F4 families of CB174R/Azucena, two plants were randomly selected and screened using simple sequence repeat markers DRRM-RF 3 -10 for Rf3 gene and RM6100 for Rf4 gene. One hundred and five plants possessing either or both of the genes were test crossed with CMS line COMS 23A. In 67 hybrids evaluated, the mean pollen fertility ranged from 97.3% (CB174R/Azucena 177-4-9) to 13.7% (CB174R/Azucena 13-2-4). The frequency of restorers was high (49.25%) followed by partial restorers (29.85%) and partial maintainers (20.90%). The selection efficiency for DRRM- RF3-10 and RM6100 markers were 75.75% and 54.54% respectively. Segregation for fertility restorer genes and pollen fertility among individual plants within a family was witnessed from molecular and phenotypic data. Based on phenotypic and marker information, it was concluded to advance 53.3% of plants to F5 generation to isolate stable restorer lines that can be exploited in future to produce highly heterotic three-line hybrids in rice.