Abstract
Quantitative trait loci conferring high grain yield under drought in rice are important genomic resources for climate resilient breeding. Major and consistent drought grain yield QTLs usually co-locate with flowering and/or plant height QTLs, which could be due to either linkage or pleiotropy. Five mapping populations used for the identification of major and consistent drought grain yield QTLs underwent multiple-trait, multiple-interval mapping test (MT-MIM) to estimate the significance of pleiotropy effects. Results indicated towards possible linkages between the drought grain yield QTLs with co-locating flowering and/or plant height QTLs. Linkages of days to flowering and plant height were eliminated through a marker-assisted breeding approach. Drought grain yield QTLs also showed interaction effects with flowering QTLs. Drought responsiveness of the flowering locus on chromosome 3 (qDTY3.2) has been revealed through allelic analysis. Considering linkage and interaction effects associated with drought QTLs, a comprehensive marker-assisted breeding strategy was followed to develop rice genotypes with improved grain yield under drought stress.
Highlights
Genetic linkages and interactions are the two most important aspects accounting for the complexity of quantitative traits such as drought tolerance in rice
grain yield (GY) QTLs were analyzed in pairs with Days to 50% flowering (DTF)/plant height (PH) QTLs for each of the three regions and LOD, and the significance of the pleiotropic effects was determined
Major drought GY QTLs that are potential candidates for an efficient drought molecular breeding program usually co-locate with other QTLs for traits such as DTF and PH, suggesting possible linkage or pleiotropy effects [9,12,13]
Summary
Genetic linkages and interactions are the two most important aspects accounting for the complexity of quantitative traits such as drought tolerance in rice. Such issues could not be efficiently addressed through a classical Mendelian approach [1]. The genetic basis of drought tolerance in rice, a model crop species, has been examined through mapping and fine mapping of QTLs. Major-effect drought grain yield QTLs have been identified, but the use of tightly linked markers is still a limitation because of their co-location with other loci that may be undesirable for a plant breeder. The most consistent drought GY QTL identified so far, qDTY1.1, co-located with QTLs related to PH and DTF under stress. PLOS ONE | DOI:10.1371/journal.pone.0151532 March 28, 2016
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