Structural and functional characteristics of two novel members of pathogensis-related multigene family of class 10 from yellow lupine+.

Abstract

PR-10 proteins (pathogensis-related), ubiquitous within the plant kingdom, are usually encoded by multigene families. To date we have identified 10 homologous pr-10 genes in a yellow lupine cDNA library. Here, the structure and expression of two newly identified yellow lupine pr-10 genes (LlYpr10-2b and LlYpr10-2f) are presented. Many potential regulatory sites were found in both gene promoters including common ones as well as those unique for each gene. However, promoter deletion analysis in transgenic tobacco plants revealed similar patterns of reporter gene (gus) expression. Shortened fragments of both gene promoters studied caused high GUS activity in leaves (along vascular bundles), stamen stigma, anthers and pollen grains. When conjugated with longer LlYpr-10.2 promoter fragments, GUS was additionally present in petal edges. Only a long fragment of the LlYpr10-2b gene promoter caused GUS expression in the stem. In yellow lupine the pr-10.2 genes are present in all studied organs, but their level of expression depends on the stage of development and is affected by wounding, oxidative stress and salicylic acid treatment. Silencing of the Llpr-10.2b gene in 4-week-old yellow lupine plants did not lead to any visible symptoms, which suggests that the function of the silenced gene is supplemented by its close homologues, still present in the studied plants.