Antisense Waxy genes with highly active promoters effectively suppress waxy gene expression in transgenic rice

To regulate Waxy (Wx) gene expression by introducing antisense genes, we co nnected the 2.3 kb Wx cDNA having 450 bp of the Wx first intron in reverse orientation to rice Wx and maize alcohol dehydrogenase1 (Adh1) promoters an d used these constructs to transform rice plants. Of 10 independent transge nic lines analysed, four lines showed various degrees of reduction in amylo se and WAXY (WX) protein levels in the endosperm, In two transgenic lines, complete absence of amylose was observed which made the seeds opaque white like glutinous rice (amylose-deficient waxy (wx) mutant), In one of the tra nsgenic lines, Al line, the presence of the antisense Wx gene cosegregated with reduction of amylose content in the endosperm, In the same line, a red uction in the level of endogenous Wx mRNA was observed in immature endosper m, Interestingly, this reduction was observed only with mature spliced tran scripts but not with unspliced transcripts. Reduced amylose synthesis was a lso observed in pollen grains of four transgenic lines. These results sugge st that integrated antisense Wx gene caused a reduction in amylose synthesi s in endosperms and pollen grains of transgenic rice carrying the antisense Wx cDNA, These results indicate that manipulation of starch and other carb ohydrates in rice grain is possible using antisense genes.