Rice forms the staple food for billions of people all around the world with a worldwide production of over 596 million tons (FAO, 1999). Over 90% of the rice is grown for consumption. The class of rice called specialty rice form only 5% of total production.
The present investigation mainly focuses on looking out for polymorphism in the enzyme soluble starch synthase, at the enzyme activity level, protein level and at the DNA level. The enzyme soluble starch synthase is a vital enzyme of the starch biosynthetic pathway. It mainly contributes towards or determines the amylose-amylopectin ratio in the endosperm starch. The amylose-amylopectin ratio is key factor determining the various processing qualities of these genotypes.
Although the investigation revealed the presence of variation in the enzyme at the enzyme activity level, isozyme level, it does not answer the question that how much the variation amounts to the differences in the properties of these select specialty rice genotypes. In the PCR analysis using STS-PCR it was found that the putative coding region for the SSSIII gene was ~1400 bp. The analysis also showed polymorphism for the waxy locus region which contributes to the amylose content.
The results indicate that there is lot of work to be done at the bio-molecular level to determine the clear cut function of each isozymes as well as other enzymes involved in starch biosynthetic pathway. The data generated from this research can be used in breeding programmes in the future.
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