Increased drought tolerance and wider adaptability of qDTY ₁₂.₁ conferred by its interaction with qDTY ₂.₃ and qDTY ₃.

• Published in: Molecular breeding 2012, Vol.30 (4), p.1767-1779
• Main Authors: Dixit, Shalabh, Mallikarjuna Swamy, B. P, Vikram, Prashant, Bernier, Jerome, Sta Cruz, M. T, Amante, Modesto, Atri, Dinesh, Kumar, Arvind
• Format: Article
• Language: English
• Subjects: drought; drought tolerance; flowering; genetic background; grain yield; harvest index; inbred lines; loci; Oryza sativa; quantitative trait loci; quantitative traits; rice
• ISSN: 1380-3743; 1572-9788

The genetic basis of high grain yield under reproductive-stage drought was studied using an F3-derived population generated from the cross of upland rice (Oryza sativa L.) cultivars Vandana and Way Rarem. Contributed by the susceptible parent Way Rarem, locus qDTY ₁₂.₁ was hypothesized to have interaction with loci from the Vandana genome to enhance the grain yield of tolerant line Vandana under drought. A test of the digenic interaction of qDTY ₁₂.₁ showed that two loci, qDTY ₂.₃ on chromosome 2 and qDTY ₃.₂ on chromosome 3, significantly increased the yield and harvest index of qDTY ₁₂.₁ -positive lines under severe upland and lowland drought conditions. qDTY ₂.₃ and qDTY ₃.₂ , in interaction with qDTY ₁₂.₁ , reduced days to flowering and plant height of qDTY ₁₂.₁ -positive lines under stress and non-stress conditions in upland. BC2F3-derived backcross inbred lines (BILs) were used to validate these results and identify new quantitative trait loci. Lines with qDTY ₂.₃ and qDTY ₁₂.₁ showed increased yield over Way Rarem under severe and moderate stress conditions, in upland. IR84996-50-4-B-4, a selection from one of the BILs, yielded more than the popular drought-tolerant cultivars Apo, UPLRi7, and IR74371-54-1-1 under severe stress conditions. Introgressed segments from Vandana also improved yield under non-stress conditions. The results indicate that digenic interactions can explain the genetic control of complex quantitative traits such as grain yield under drought, and a few interacting loci with large effects on grain yield or yield-related traits may enhance drought response across a wide range of genetic backgrounds and environments when introgressed together.