Study of fertility restoration and genetic diversity of drought-tolerant breeding lines for hybrid rice (Oryza sativa L.) development

The identification of fertility restoration and genetic diversity of drought-tolerant breeding lines will be useful for the development of promising drought-tolerant rice hybrids. The extent of genetic variation of 204 drought-tolerant breeding lines based on the coefficient of parentage (COP) and test crossing with IR 58025A is studied. The linked molecular markers to Rf genes were screened on identified maintainers and restorers. The average value of COP for 204 drought-tolerant breeding lines was 0.21, which indicates genetic divergence in breeding lines. Four major groups comprising of 81 IR 64 type, 37 Apo type, 28 Vandana type, 6 WAB type and 52 others were identified. Out of 204 breeding lines, 37 (18.14%) maintainers, 55 (26.96%) partial maintainers, 63 (30.88%) partial restorers and 49 (24.02%) restorers were identified. Rf genes linked molecular markers RM7466 and RM443 on chr. 1; RM6344 on chr. 7 and RM6100, RM1108, RM216, RM171 and RM244 on chr. 10 were found associated with restorers and maintainers. These Rf genes linked molecular markers might be furthermore used in marker-assisted restorer selection in cytoplasmic male sterile-WA system from large source nurseries to avoid usual test crosses in the hybrid rice development programme. The identified restorer and maintainers may be used for the development of high-yielding drought-tolerant rice hybrids.