Identification of variant transcripts of waxy gene in non-glutinous rice (O. sativa L.) with different amylose content.

The identification of a number of cDNA sequences at the splice sites of Waxy (Wx) gene in rice endosperm point to the variation of gene expression associated with the G to T mutation at the 5' splice site of intron 1 and the alternative splicing produces variants transcripts by shortening. As consequence, variation of amylose content in this tissue. To determine whether the splicing type of Wx genes are also found in rice endosperm of Thai rice cultivars, cDNA of the gene have been isolated by using RT-PCR and sequenced. Analysis of the twenty-five cDNA clones led to the identification of the splicing pattern of the gene, four cryptic splice sites was found in cDNA sequences of low-amylose cultivars (<20%), while two cryptic splice sites of intermediate (20-25%) and high (>25%) amylose cultivars were characterized. The alternatively spliced transcripts were observed in much higher proportion in low amylose cultivars than that in intermediate and high amylose cultivars. These findings raise a possibility explanation that the degree of amylose content in non-glutinous rice cultivars may reflect to the amount of efficiently spliced transcripts.