Identification of QTLs for agronomic traits under lowland drought stress in crosses of rice (Oryza sativa CV IR64) × O. glaberrima
2009
Bimpong, I.K. | Mendoza, E.M.T. | Serraj, R. | Hernandez, J. | Mendioro, M.S. | Ramos, J. | Brar, D.S.
Drought is one of the most important abiotic stresses affecting rice production. There is an urgent need to develop rice varieties that use water efficiently and are tolerant to drought during different stages of crop growth. O. glaberrima, African rice species is low yielding but has tolerance to drought and other stresses. A set of 513 BC2F3 alien introgression lines (AILs) derived from crosses of O.sativa × O.glaberrima was evaluated under drought stress in lowland nurseries at 2 locations in 2008. Of these, 33 AILs had higher yield per plant than the recurrent parent IR64. A sub-set of 200 AILs was selectively genotyped with 173 SSR and STS markers. QTL analysis was conducted using QTL Mapper 1.60 for single-point and Map manager QTX20 for interval mapping. The analysis revealed 45 QTLs for different agronomic traits of which 18 are new. O. glaberrima contributed 67% alleles to the newly identified QTLs. One of the QTLs at RM208 on chromosome 2 was found to have positive effect on yield under stress accounting for 22% of the genetic variation. Association between markers and yield related traits was examined in three ways: (1) by significance of marker-trait correlations, (2) Linkage disequilibrium (LD) profiles over chromosomes and (3) marker-trait associations found in other QTL studies. Significant LD between markers on different chromosomes was detected in different groups (1) high and low yielding under stress, (2) high yielding lines from non stress and (3) randomly selected lines. QTLs identified under drought stress for yield and yield components would be further validated in field experiments and use in marker-assisted selection
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