Submitted to: American Association of Cereal Chemists Meetings
Publication Type: Proceedings
Publication Acceptance Date: 8/1/1997
Publication Date: N/A
Technical Abstract: The rice waxy gene encodes a granule bound starch synthase necessary for the synthesis of amylose in endosperm. We have previously shown that a CT micorsatellite in the 5 prime untranslated region of the waxy gene can distinguish at least 7 alleles that account for more than 80 percent of the variation in apparent amylose content in an extended pedigree of 89 long-, medium- and short-grain US rice cultivars (Ayres et al., Theor. Appl. Genet. 94:773-781). Furthermore, all the cultivars with 18 percent or less amylose where shown to have the sequence AGTTATA at the putative leader intron 5 prime region splice site, while all cultivars with a higher pro- portion of amylose had AGGTATA. Here we directly demonstrate that this single base mutation reduces the efficiency of Wx mRNA processing and ac- tivates splicing at three cryptic sites. The predominant leader intron splice site in low amylose varieties is 93 bp upstream of the site used in intermediate and high amylose varieties, immediately adjacent to the CT microsatellite we previously demonstrated to be tightly correlated with amylose content.