Mapping of genes for cooking and eating qualities in Thai jasmine rice (KDML105)

Abstract

Thai jasmine rice, KDML 105, is known as the best quality rice. It is known not only for its aroma but also for its good cooking and eating qualities. Amylose content (AC), gel consistency (GC) and gelatinization temperature (GT) are important traits determining rice quality. A population of recombinant inbred lines (RIL) derived from KDML105 x CT9993 cross was used to study the genetic control of AC, GC and GT traits. A total of 191 markers were used in the linkage map construction. The 1605.3 cM linkage map covering nearly the whole rice genome was used for QTL (define QTL) analysis. Four QTLs for AC were detected on chromosomes 3, 4, 6 and 7. These QTLs accounted for 80% of phenotypic variation explained (PVE) in AC. The presence of one major gene as well as several modifiers was responsible for the expression of the trait. Two QTLs on chromosome 6 and one on chromosome 7 were detected for GC, which accounts for 57% of PVE. A single gene of major effect along with modifier genes controls GC from this cross. The QTLs in the vicinity of waxy locus were major contributors in the expression of AC and GC. The finding that the position of QTLs for AC and GC were near each other may reflect tight linkage or pleiotropy. Three QTLs were detected, one on chromosome 2 and two on chromosome 6, which accounted for 67% of PVE in GT. Just like AC and GC, one major gene and modifier genes governed the variation in GT resulting from the KDML105 x CT9993 cross. Breeding for cooking and eating qualities will largely rely on the preferences of the end users.