A QTL for rice grain yield in aerobic environments with large effects in three genetic backgrounds

Abstract

A large-effect QTL associated with grain yield in aerobic environments was identified in three genetic backgrounds, Apo/(2)*Swarna, Apo/(2)*IR72, and Vandana/(2)*IR72, using bulk-segregant analysis (BSA). Apo and Vandana are drought-tolerant aerobic-adapted varieties, while Swarna and IR72 are important lowland rice varieties grown on millions of hectares in Asia but perform poorly in aerobic conditions. Two closely linked rice microsatellite (RM) markers, RM510 and RM19367, located on chromosome 6, were found to be associated with yield under aerobic soil conditions in all three backgrounds. The QTL linked to this marker, qDTY6.1 (DTY, grain yield under drought), was mapped to a 2.2 cM region between RM19367 and RM3805 at a peak LOD score of 32 in the Apo/(2)*Swarna population. The effect of qDTY6.1 was tested in a total of 20 hydrological environments over a period of five seasons and in five populations in the three genetic backgrounds. In the Apo/(2)*Swarna population, qDTY6.1 had a large effect on grain yield under favorable aerobic (R (2) ≤ 66%) and irrigated lowland (R (2) < 39%) conditions but not under drought stress; Apo contributed the favorable allele in all the conditions where an effect was observed. In the Apo/IR72 cross, Apo contributed the favorable allele in almost all the aerobic environments in RIL and BC(1)-derived populations. In the Vandana/IR72 RIL and BC(1)-derived populations, qDTY6.1 had a strong effect on yield in aerobic drought stress, aerobic non-stress, and irrigated lowland conditions; the Vandana allele was favorable in aerobic environments and the IR72 allele was favorable in irrigated lowland environments. We conclude that qDTY6.1 is a large-effect QTL for rice grain yield under aerobic environments and could potentially be used in molecular breeding of rice for aerobic environments.

Soil water potential and recoverable water stress in drought tolerant and susceptible rice varieties

“…Similar results were observed by Lilley and Fukai (1994b). Yield components such as spiklelet fertility and the number of panicles per hill were also low in our study as have been observed in other studies (Garrity and O'Toole, 1994;Bernier et al, 2007;Kumar et al, 2008;Venuprasad et al, 2009Venuprasad et al, , 2012Verulkar et al, 2010). These observations suggest that the imposition of regulated water stress during vegetative growth may lead to yield advantage even for the drought-susceptible rice varieties.…”

“…There was 12.5% reduction in yield with increased stress level in vegetative stress in 2012 growing season. This was an exceptional behaviour in this experiment, which may have occurred because of highly drought susceptible nature of IR72 (Venuprasad et al, 2012) and significant negative correlation between chaffy grains per hill and terminal SWP. As a lowland reference variety, IR72 showed an average yield reduction of 67-80% (Belder et al, 2004;Atlin et al, 2006;Serraj et al, 2011;Venuprasad et al, 2011) and failed to perform in aerobic condition (Zhao et al, 2010), due to severely reduced biomass and harvest index.…”

The effects of drought on rice cultivation in sub-Saharan Africa and its mitigation: A review

“…This QTL has also been reported in CT9993-5-10-1-M/IR62266-42-6-2 and Apo/IR64 populations Venuprasad et al, 2012a).…”

Breeding high-yielding drought-tolerant rice: genetic variations and conventional and molecular approaches

“…BSA was successfully used for the first time to identify such large-effect QTLs for grain yield under reproductive-stage drought (Venuprasad et al , 2009). qDTY 6.1 , another large-effect QTL for grain yield under favourable aerobic and irrigated lowland conditions, was identified in this population (Venuprasad et al , 2012 a ). This QTL explained an R 2 of up to 66% and 39%, respectively, under upland and lowland non-stress conditions.…”