Transformation of antisense constructs of the chalcone synthase gene superfamily into Gerbera hybrida: differential effect on the expression of family members

Abstract

Suppression of gene expression using antisense technology has been successful in various applications. In this paper we report differential inhibition of gene expression of the chalcone synthase (chs) gene superfamily members in transgenic Gerbera hybrida (Asteraceae) plants. We have transformed two different cDNAs of the chs gene family, gchs 1 [4] and gchs2, in antisense orientation under control of the CaMV 35S promoter into gerbera. Gchs1 codes for an enzyme with chalcone synthase activity while gchs2 is a more diverged member of the gene family having distinct structure and expression pattern. Furthermore, gchs2 is evidently not involved in anthocyanin synthesis and encodes an enzyme with novel catalytic properties. In both cases effective blocking of the resident sense gene expression was detected. In addition, the transformation affected differentially the expression of other members of the chs gene family. The degree of inhibition appeared to depend on the sequence homology between the antisense and the target genes. In the unevenly coloured inflorescences detected among anti-gchs1 transformants during their growth, relaxation of the antisense effect was here shown to start from the most distant member of the gene family, further demonstrating the influence of sequence homology in the stability of antisense inhibition.