Breeding for drought tolerance based on direct selection for high grain yield under drought has been hindered by the complex nature of drought tolerance mechanisms and the approaches used. Molecular marker-based approaches are a promising alternative. In this study, 30 rice (Oryza sativa L.) accessions cultivated in Nigeria were screened in a greenhouse for drought tolerance based on morpho-physiological traits and assessed for DNA polymorphisms using SSR markers for possible marker-trait associations. Our results showed that five Nigerian rice landraces (IJS-02, IJS-09, IK-PS, IK-FS and Lad-f) and three improved varieties (FARO-44, IR-119 and IWA-8) were highly drought tolerant. Sixteen of 20 markers tested yielded amplified products and generated 221 alleles (4 to 5 alleles per marker) with PIC values ranging from 0.24 to 0.95 per marker. Although, none of the markers were present in all the accessions that were found to be highly drought tolerant with respect to any particular morph-physiological trait, some of the markers (RM252, RM331, RM432, RM36, RM525, RM260 and RM318) amplified alleles unique to nearly all the tolerant Nigerian landraces (IJS-02, IJS-09, IK-PS, IK-FS) and FARO-11, a drought tolerant control. These markers may be usefully exploited for molecular breeding of rice for drought tolerance.
Key words: Nigeria, climate change, rice, drought stress, drought tolerance, SSR markers, molecular breeding.
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