Association Mapping of Yield and Yield-related Traits Under Reproductive Stage Drought Stress in Rice (Oryza sativa L.)

• Published in: Rice (New York, N.Y.) Vol. 10; no. 1; p. 21
• Main Authors: Swamy, B. P. Mallikarjuna, Shamsudin, Noraziyah Abd Aziz, Rahman, Site Noorzuraini Abd, Mauleon, Ramil, Ratnam, Wickneswari, Sta. Cruz, Ma. Teressa, Kumar, Arvind
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-12-2017; Springer Nature B.V; SpringerOpen
• Subjects: Admixtures; Agriculture; Association mapping; Biomedical and Life Sciences; Chromosomes; Crop yield; Drought; Drought resistance; Flowering; Gene loci; Gene mapping; Genes; Genetic diversity; Germplasm; Grain; Heritability; Interspecific hybridization; Life Sciences; Linkage analysis; Linkage disequilibrium; Mapping; Markers; Original; Original Article; Phenotypic variations; Plant Breeding/Biotechnology; Plant Ecology; Plant Genetics and Genomics; Plant reproduction; Plant Sciences; Quantitative trait loci; Rice; Screening; Stress analysis; Subgroups; Association mapping; Genetic diversity; Drought; Genes
• ISSN: 1939-8425; 1939-8433; 1934-8037
• DOI: 10.1186/s12284-017-0161-6

Background
The identification and introgression of major-effect QTLs for grain yield under drought are some of the best and well-proven approaches for improving the drought tolerance of rice varieties. In the present study, we characterized Malaysian rice germplasm for yield and yield-related traits and identified significant trait marker associations by structured association mapping.
Results
The drought screening was successful in screening germplasm with a yield reduction of up to 60% and heritability for grain yield under drought was up to 78%. There was a wider phenotypic and molecular diversity within the panel, indicating the suitability of the population for quantitative trait loci (QTL) mapping. Structure analyses clearly grouped the accessions into three subgroups with admixtures. Linkage disequilibrium (LD) analysis revealed that LD decreased with an increase in distance between marker pairs and the LD decay varied from 5–20 cM. The Mixed Linear model-based structured association mapping identified 80 marker trait associations (MTA) for grain yield (GY), plant height (PH) and days to flowering (DTF). Seven MTA were identified for GY under drought stress, four of these MTA were consistently identified in at least two of the three analyses. Most of these MTA identified were on chromosomes 2, 5, 10, 11 and 12, and their phenotypic variance (PV) varied from 5% to 19%. The
in silico
analysis of drought QTL regions revealed the association of several drought-responsive genes conferring drought tolerance. The major-effect QTLs are useful in marker-assisted QTL pyramiding to improve drought tolerance.
Conclusion
The results have clearly shown that structured association mapping is one of the feasible options to identify major-effect QTLs for drought tolerance-related traits in rice.