Studies on genetic variability and identification of sequence variations among cultivars and landraces of rice ( Oryza sativa L.) for apparent amylose and amylopectin contents

Starch is the main component of cereals like rice. It is mainly composed of amylose and amylopectin. Apparent amylose content (AAC) in rice grain controlled by granule bound starch synthase enzyme (GBSS) is the key factor determining cooking and processing quality. The present study has been attempted to decipher the genetic variability among 36 cultivars of rice for agro-morphological parameters along with AAC and amylopectin content, to determine the extent of association among yield and its contributing characters and to detect the sequence variations among the cultivars having differential AAC. Results revealed the presence of adequate genetic variability among the tested rice cultivars for yield attributing traits, as well as their AAC and amylopectin content. Most of the yield attributing traits was under control of additive genes. Genetic diversity study of the tested rice cultivars grouped them into four clusters. The nucleotide sequence and derived amino acid sequence variations among the region spanning between the intron 7 and exon 10 of GBSSI allele from the rice cultivars differing in AAC detected the presence of several SNPs, deletions and insertions within the tested exon and intron regions. Presence of methionine (M) or isoleucine (I) at 308 aa position and presence of phenylalanine (F) at 425 or 434 aa position of GBSSI protein across the tested rice cultivars can be exploited in marker-assisted breeding programme for developing high yielding rice cultivars with proper grain quality as per consumer’s preference.