Functional Analysis Of Starch-synthesis Genes In Determining Rice Eating And Cooking Qualities

Apparent amylose content (AAC), gel consistency (GC), and gelatinization temperature (GT) are recognized as the most important determinants of rice eating and cooking qualities. The contributions of major starch-synthesis genes to these three traits have been investigated in the three consecutive experiments. In an initial QTL mapping with 130 doubled haploid (DH) lines, derived from an inter-subspecific cross of'Nanjing11'/'Balilla', the major QTLs responsible for AAC, GC, and GT were coincided with the Wx (granule-bound starch synthase gene), Wx, and SssIIa (soluble starch synthase gene) loci, respectively. In the next experiment, the markers tagged to major starch-synthesis genes were developed and used to genotype each DH line. As shown, the Wx locus was a principal determinant for both AAC and GC, and could account for 58.5% and 38.9% of the phenotypic variations, respectively; while, the SssIIa locus was associated with GT, and could explain 25.5% of the observed variation. Eventually, a F2 population consisting of 501 individuals, derived from an inter-subspecific cross of the two sticky rice varieties'Suyunuo'and'Yangfunuo 4', was examined with the gene-tagged markers. In the absence of the Wx gene, no starch-synthesis genes investigated could dominate the GC variation, however, the Sss...