Marker-Assisted Backcross Breeding for Improvement of Submergence Tolerance and Grain Yield in the Popular Rice Variety, ‘Maudamani’

Abstract

Background: Submergence stress due to flash flood reduces rice yield drastically in sensitive varieties. Maudamani is a high yielding popular rice variety but highly susceptible to submergence stress. The Sub1 and yield component QTL, GW5 were transferred into the popular high yielding variety for enhancing submergence tolerance and yield. Methods: Sub1 and GW5 QTLs were transferred into Maudamani variety by adopting marker-assisted backcross breeding method. The target QTLs were selected by foreground selection in each backcross generation progenies to track the target QTLs. Recipient parent’s genome recovery was accelerated by adopting background selection in each backcross generation progenies carrying the target QTLs. Results: The two target QTLs were tracked in each backcross generation progenies by employing the tightly linked and direct markers. Background screening was performed in each backcross generation progenies carrying the target QTLs by using 57 background markers for enhancing the recovery of recipient parent’s genome content. The selected progenies containing highest genome recovery of the parent was hybridized with recipient parent, Maudamani. Finally, the selected BC3F1 plant containing highest recipient parent genome content and the two target QTLs was self-pollinated. In BC3F2 generation, two QTLs, Sub1 and GW5 along with recipient parent’s yield component QTLs, OsSPL14, Gn1a and SCM2 were tracked for their homozygous state in the progenies. Amongst the developed pyramided lines, six lines showed tolerance to submergence for 14 days and also exhibited higher grain yield than both the parents. The pyramided lines, MSS 607-116-541-117 and MSS 607-116-541-436 produced >9 t/ha grain yield showing an advantage of >5% over the popular recipient variety. Few pyramided lines were similar in appearance and quality traits with the recipient parent. Conclusion: The pyramided lines will be useful as potential donors for the QTLs Sub1+ OsSPL14+ Gn1a + GW5 + SCM2 and also as cultivars.