Abstract
The granule-bound starch synthase I (GBSSI) catalyzes the synthesis of amylose in plastids. We have reported the necleotide sequences of the GBSSI genomic clone and the cDNA clone obtained by screening libraries. In this study we analyzed multiple other clones in order to investigate polymorphism in the GBSSI gene of sweetpotato, hexaploid plant. Five genomic clones and two cDNA clones possessing an intact ORF were analyzed and the nucleotide sequences were classified into five groups. The nucleotide sequence identity of the ORF region was 98.1%-98.9%. The amino acid sequence identity of GBSSI mature protein was 99.1%-99.6% among five groups. This result suggests that sweetpotato has heterogeneous group of GBSSI proteins in plastids. Comparison of the necleotide sequence of introns showed polymorphism in length of all 13 introns (1-89 bp difference). Analysis of the partial length clones is in progress.
