Developmental-regulation and tissue-specific expression of two different seed promoter GUS-fusions in transgenic lines of Vicia narbonensis

Abstract

Summary Two different promoter/GUS fusions driven either by the leguminB4 promoter (leB4) or the promoter of the unknown seed protein (usp) from Vicia faba were introduced into Vicia narbonensis to study the regulation and the activity of seed specific promoters under homologous conditions. For each construct two lines with a single copy insertion of the T-DNA were propagated and subjected to further analysis. Hemi- and homozygous subpopulations were produced up to the sixth generation and the amount of β-glucuronidase as well as the course of transcript accumulation of GUS mRNA and several seed protein mRNAs were determined during seed development. Quantitative GUS assays revealed a correlation between GUS accumulation and the allelic state of the plants (hemWhomozygous for the transgene). The two lines expressing the usp-GUS fusion showed GUS activity from the globular stage of seed development (day 5 to 7 after pollination), whereas in lines containing the leB4-GUS fusion, the GUS expression and transcript accumulation started at the mid-cotyledon stage (approx. 15 DAP). In one of the two leB4-GUS lines GUS expression was not restricted to the embryo exclusively, activity was also found in the seed coat. The expression of the GUS gene driven by the two seed specific promoters in Vicia narbonensis is very similar to that which has been reported on the developmental expression of the original genes in Vicia faba . The transgenic lines generated in the present study are useful tools for examining the functions, the mechanisms, and the regulation of storage protein synthesis.