The pea PsEND1 promoter drives the expression of GUS in transgenic wheat at the binucleate microspore stage and during pollen tube development

Abstract

Many plant genetic engineering applications require spatial expression of genes which in turn depends upon the availability of specific promoters. In cereals, genetic modification of flowering and grain setting to influence yield and grain quality is of significant interest. PsEND1 is a pea promoter that displays expression in the epidermis, connective tissue, endothecium and middle layers during different stages of anther development. No homeologous sequence of this promoter or its coding sequence has been found in cereals. This present work aimed at the characterization of the pea PsEND1 promoter driving the expression of the gusA gene in transgenic wheat. Nine transgenic lines were produced by particle bombardment and analyzed for the expression of the gusA gene throughout development by histochemical GUS staining and by RT-PCR in vegetative and reproductive tissues and organs. Expression of the gusA gene was first detected during pollen development, in microspores at binucleate stage. Activity of the gusA gene was also found in mature pollen, after anthesis. Following pollen grain germination, expression of the gusA gene was seen from an early stage of pollen tube formation until advanced stages, approaching the ovary. No further expression of the gusA gene was detected after fertilization, nor during seed development. The results reported here show that the PsEND1 promoter is functional in wheat and its patterns of expression may be of interest for the application of genetic modification in wheat breeding.