Quantitative trait loci associated with drought tolerance at reproductive stage in rice

Lanceras, J.C. and Pantuwan, G. and Jongdee, B. and Toojinda, T. (2004) Quantitative trait loci associated with drought tolerance at reproductive stage in rice. Plant Physiology, 135 (1). pp. 384-399.

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Drought is a major constraint to rice (Oryza sativa) yield and its stability in rainfed and poorly irrigated environments. Identifying genomic regions influencing the response of yield and its components to water deficits will aid in our understanding of the genetics of drought tolerance and development of more drought tolerant cultivars. Quantitative trait loci (QTL) for grain yield and its components and other agronomic traits were identified using a subset of 154 doubled haploid lines derived from a cross between two rice cultivars, CT9993-510 to 1-M and IR62266-42 to 6-2. Drought stress treatments were conducted using a line source sprinkler irrigation system, which provided a linearly decreasing level of irrigation coinciding with the sensitive reproductive growth stages. The research was conducted at the Ubon Rice Research Centre, Ubon, Thailand, during the wet season of 2000. A total of 77 QTL were identified for grain yield and its components under varying levels of water stress (W0, full irrigation; W1-W4, mid- to severe water deficit). Out of the total of 77 QTL, the number of QTL per trait were: 7 for grain yield (GY); 8 for biological yield (BY); 6 for harvest index (HI); 5 for days to flowering after initiation of irrigation gradient (DFAIG); 10 for total spikelet number (TSN); 7 for spikelet sterility (PSS); 23 for panicle number (PN); and 11 for plant height (PH). The phenotypic variation explained by individual QTL ranged from 7.5 to 55.7%. Under well-watered conditions, we observed a high genetic association for BY, HI, DFAIG, PSS, TSN, PH, and GY. However, only BY and HI were found to be significantly associated with GY under drought treatments. QTL flanked by markers RG104 to RM231, EMP2_2 to RM127, and G2132 to RZ598 on chromosomes 3, 4, and 8 were associated with GY, HI, DFAIG, BY, PSS, and PN under drought treatments. The aggregate effects of these QTL on chromosomes 3, 4, and 8 resulted in higher grain yield. These QTL will be useful for rainfed rice improvement, and will also contribute to our understanding of the genetic control of GY under drought conditions at the sensitive reproductive stage. Close linkage or pleiotropy may be responsible for the coincidence of QTL detected in this experiment. Digenic interactions between QTL main effects for GY, BY, HI, and PSS were observed under irrigation treatments. Most (but not all) DH lines have the same response in measure of productivity when the intensity of water deficit was increased, but no QTL by irrigation treatment interaction was detected. The identification of genomic regions associated with GY and its components under drought stress will be useful for marker-based approaches to improve GY and its stability for farmers in drought-prone rice environments.

Item Type: Article
Additional Information: SNNigam Collection
Uncontrolled Keywords: Quantitative Trait, Drought Tolerance, Reproductive Stage, Rice
Author Affiliation: Rice Gene Discovery Unit, BIOTEC, Kasetsart University, Kamphangsaen Campus, Thailand.
Subjects: Crop Improvement
Divisions: Other Crops
Depositing User: Mr Arbind Seth
Date Deposited: 17 Apr 2013 08:51
Last Modified: 17 Apr 2013 08:51
Official URL: http://dx.doi.org/10.1104/pp.103.035527
URI: http://eprints.icrisat.ac.in/id/eprint/10218

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