Genetic Effects of Wx Allele Combinations on Apparent Amylose Content in Tropical Hybrid Rice

Apparent amylose content (AAC), as one of the most important quality traits of rice grain, is primarily controlled by the Wx gene, which encodes a granule-bound starch synthase. Effects of putative alleles of Wx of tropical rice hybrids generated from parents with three different nonglutinous Wx alleles (Wxa, Wxb, and Wxin) were examined in a multienvironment trial. Genotypes of Wxb/Wxin and Wxin/Wxin were associated with intermediate AAC (20.2–23.7%), and genotype of Wxa/Wxa was associated with high AAC (24.9–28.0%). Wx alleles of Wxin/Wxin could be the most favorable combinations in selecting hybrid parents with desirable intermediate amylose content (20–25%) for rice consumers of South and Southeast Asian countries. Genotype and genotype × environment interaction were the major contributing factors to the variation in parental accessions’ and hybrids’ AAC, and in terms of AAC, hybrids were more sensitive than parental varieties to environment. Genotypes of Wxa/Wxa, Wxa/Wxin, and Wxin/Wxin showed higher...