Marker assisted introgression of QTLs governing yield under drought stress in Rice Oryza sativa L

Abstract

Through conventional breeding limited progress has been made in development of drought tolerant rice varieties due to the quantitative nature of drought tolerance. Identification of qDTY QTLs that confer yield under drought stress pave way for direct selection for yield under stress and transfer of these QTLs through MABB (Marker assisted backcross breeding) leads to improvement of popular varieties with drought tolerance. Based on this, present investigation was carried out to pyramid three QTLs, which confer yield under drought stress viz., qDTY1.1 and qDTY3.1 from Apo and qDTY12.1 from Way Rarem into ADT(R)45, a popular variety of Tamil Nadu. BC3F1 of ADT(R)45/Apo, BC3F1 of ADT(R)45/Way Rarem and Intermated F1 (BC2F1 of ADT(R)45/Way Rarem // BC2F1 of ADT(R)45/Apo) were developed through MABB and were forwarded as BC3F2 and inter-mated F2 population. newlineThrough marker assisted selection (MAS) in BC3F2 and inter-mated F2, 148 plants with different qDTY QTL combinations were identified and designated as Backcrossed inbred lines (BILs). These 148 BILs (BC3F3 and inter-mated F3) were advanced as families and 31 BILs out of 148 were rejected as they were segregating for morphological traits. Selected 117 BILs were screened under direct seeded rainfed condition at Agricultural newlineResearch Station, Paramakudi, Tamil Nadu Agricultural University, which was target production environment. Analysing mean values of nine yield traits of BILs under rainfed environment, analysis of variance revealed that variance due to genotypes were highly significant for all the traits studied, which indicated significant amount of variability present among the BILs for the yield contributing traits. newlineGCV, heritability at broad sense and genetic advance as percent of mean were high for three traits viz., number of productive tillers per plant, total number of tillers per plant and single plant yield, which indicated predominance of additive gene action for these characters.