Abstract
BackgroundThree drought yield QTLs, qDTY2.2, qDTY3.1, and qDTY12.1 with consistent effect on grain yield under reproductive stage drought stress were pyramided through marker assisted breeding with the objective of improving the grain yield of the elite Malaysian rice cultivar MR219 under reproductive stage drought stress. Foreground selection using QTL specific markers, recombinant selection using flanking markers, and background selection were performed. BC1F3-derived lines with different combinations of qDTY2.2, qDTY3.1, and qDTY12.1 were evaluated under both reproductive stage drought stress and non-stress during the dry seasons of 2013 and 2014 at IRRI.ResultsThe grain yield reductions in the stress trials compared to non-stress trials ranged from 79 to 93 %. In the stress trials, delay in days to flowering and reduction in plant height were observed. In both seasons, MR219 did not produce any yield under stress, however it produced a yield of 5917 kg ha−1 during the 2013 dry season and 8319 kg ha−1 during the 2014 dry season under non-stress. Selected introgressed lines gave a yield advantage of 903 to 2500 kg ha−1 over MR219 under reproductive stage drought stress and a yield of more than 6900 kg ha−1 under non-stress during the 2014 dry season. Among lines with single qDTY, lines carrying qDTY2.2 provided a higher yield advantage under reproductive stage drought stress in the MR219 background. Two-qDTY combinations (qDTY3.1+qDTY2.2 and qDTY3.1+qDTY12.1) performed better than lines with three qDTY combinations, indicating the absence of positive interactions between the three qDTYs.ConclusionWe successfully developed drought-tolerant MR219 pyramided lines with a yield advantage of more than 1500 kg ha−1. Differential yield advantages of different combinations of the qDTYs indicate a differential synergistic relationship among qDTYs. This is the first report on the successful effect of qDTYs in increasing the yield under drought in genetic backgrounds other than those in which the qDTYs were earlier identified.
Highlights
Three drought yield QTLs, qDTY2.2, qDTY3.1, and qDTY12.1 with consistent effect on grain yield under reproductive stage drought stress were pyramided through marker assisted breeding with the objective of improving the grain yield of the elite Malaysian rice cultivar MR219 under reproductive stage drought stress
Under NS, the yield levels of the recipient parent were higher compared to other QTL classes. These results indicate that pyramided lines (PLs) with qDTY/s were quite effective in enhancing grain yield (GY) under severe reproductive stage drought stress (RS) conditions (Fig. 5)
Only one study has reported on improving drought tolerance in the Malaysian mega-variety MR219 which is known to be highly sensitive to drought [25]
Summary
Three drought yield QTLs, qDTY2.2, qDTY3.1, and qDTY12.1 with consistent effect on grain yield under reproductive stage drought stress were pyramided through marker assisted breeding with the objective of improving the grain yield of the elite Malaysian rice cultivar MR219 under reproductive stage drought stress. The ability of the rice crop to withstand dry conditions and to reproduce in limited water conditions is essential for rice production to still prosper despite drought [12, 13]. It is, vital to focus on the development of high yielding droughttolerant rice cultivars which have a targeted yield advantage of at least 1000 kg ha−1 over popular and widely adapted varieties under drought. Breeding efforts for drought-tolerant rice varieties are limited due to factors such as the difficulty of defining a representative RS condition as well as the low heritability (H) of yield component traits such as spikelet sterility, relative water content, root pulling force, root dry weight, and harvest index under RS as these are highly influenced by multiple genes, the environment, and the interrelation between genotype and environment as well as interaction with other abiotic and biotic stresses [14]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
