Determination of amylose content and expression analysis of the Granular-Bound Starch Synthase I (GBSS1) gene in rice grains

A O Oko,M K Lal,S G Sharma,A Kumar

doi:10.4314/njb.v34i1.10

Abstract

The study determined amylose content and expression level of GBSS I gene in rice grain. A total of eighteen (18) rice ( Oryza sativa L) cultivars of Indica varieties were collected from the National Rice Research Institute (NRRI) Cuttack and screened for their percentage amylose contents. Three cultivars namely Bindli, Naveen and Pooja which had contrasting characters in percentage amylose were then planted and used for the expression analysis. In the first stage of grain filling Bindli had 0.27 fold expression while Pooja and Naveen had 1.72 and 1.44 respectively. There was dramatic increase in the expression levels of the gene in the middle stage of grain filling in all the three cultivars with relative folds of 10.97, 42.71 and 27.34 recorded in Bindli, Pooja and Naveen respectively. However, at the last stage of grain filling, GBSS1 expression was low compared to the second stage with expression folds of 7.12, 7.55 and 1.67 in Bindli, Pooja and Naveen cultivars respectively. On the whole, Bindli cultivar showed lowest expression of the gene (GBSS1) when compared to Pooja and Naveen. Key words: rice gene, amylose, expression analysis, GBSS1

Highlights

Starch is a glucose polymer that is an important carbohydrate and energy source in the human diet
A total of eighteen (18) rice (Oryza sativa L) cultivars of Indica varieties were collected from the National Rice Research Institute (NRRI) Cuttack and screened for their percentage amylose contents
Amylose is a linear and relatively short polymer of glucose units linked by α(1 4) glycosidic bonds, while amylopectin is a branched and longer polymer where glucose units are arranged linearly through α(1 4) glycosidic bonds, with branches emerging through α(1 6) glycosidic bonds occurring every twenty-four to thirty glucose units (Sajilata et al, 2006)

Summary

Introduction

Starch is a glucose polymer that is an important carbohydrate and energy source in the human diet. Starch comprises two glucose polymers which are amylose and amylopectin. The amylose content in rice grain starch is of great importance when determining the quality of the rice grain (Fasahat et al, 2014). It affects the stability, dietary fiber content, texture, and viscosity of processed rice (Morita et al, 2002). The cooking and eating characteristics of rice which are the bases of choice for the consumers is determined by the amylose content and gelatinization temperature (Samina et al, 2012; Oko et al, 2012). A positive correlation exists between amylose content and length/breadth ratio in relation to elongation of cooked rice (Rachel et al, 2013).

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