QTL mapping for zinc deficiency tolerance in rice (Oryza sativa L.)
2009
Refuerzo, L. | Mercado, E.F. | Arceta, M. | Sajese, A.G. | Gregorio, G. | Singh, R.K., International Rice Research Inst., DAPO Box 7777, Metro Manila (Philippines)
Zinc deficiency is the third most limiting constraints after nitrogen and phosphorus in cereals, especially in rice and wheat. Grain yield losses due to Zn have been reported in rice as high as 80%, along with reduced grain Zn level (Alloway, 2004). Rice has enormous variability for Zn deficiency tolerance. Thus the most viable option is to convert adapted but sensitive rice varieties to Zn deficiency through marker assisted backcrossing, provided that the QTL or major gene underlying this trait is mapped. The present study is an effort to identify the big effect QTLs for the Zn deficiency tolerance. A large F2 mapping population of 500 individuals, derived from a cross between highly contrasting parents, i.e., A69-1 (tolerant) and Kinandang Patong (sensitive), was phenotyped for tolerance to very deficient Zn ( 0.1 ppm) conditions in Tiaong (Philippines) soil. Out of the total 671 SSR markers used for parental polymorphism, only 133 (about 20%) were found polymorphic. These markers are being run on 135 F2 plants for genotyping using selective mapping, involving 3 sets of 45 genotypes from tolerant extremes, sensitive extreme and the random sample. Work is still in progress; however considering good segregation, probably due to contrasting parents for Zn deficiency tolerance, big effect QTLs for this trait are expected.
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