Effect of an Antisense Sequence on Rice Allergen Genes Comprising a Multigene Family

An antisense gene strategy was used to suppress the expression of rice allergen (RA) genes that comprise a multigene family. We produced transgenic rice plants harboring antisense genes that consisted of cDNA for a major RA driven by promoters of the RA, rice starch branching enzyme, rice prolamine and rice glutelin genes, which are specifically expressed in developing seeds. Among more than 100 transformants, the RA content in some transformants was reduced to no more than 20 % of that in non-transformant. However, an allergen-free transformant was not obtained. Since the transcribed antisense mRNAs are not fully used for suppression of the RA genes in transformants, we examined here the possibility of a spatial or temporal difference in the expression of the introduced antisense and endogenous RA genes. However, we found no remarkable difference in the place or timing of their expression. We also examined the effect of antisense genes on each of the genes in the RA family in transformants by twodimensional electrophoresis and immunoblotting. The results showed that the contents of the major RA and other RAs with nucleotide sequences that are highly homologous to the antisense sequence were markedly lowered, while the contents of other RAs with sequences showing relatively low homology to the major RA were hardly affected. These results suggest that the effect of the antisense gene on the RA gene family depends on the homology between the antisense sequence used and the target sequence.