Involvement of SLR1 genes in pollen adhesion to the stigmatic surface in Brassicaceae

Abstract

 The S-locus-related gene SLR1 is highly conserved and highly expressed in several species of the Brassicaceae family. Its function has not been determined, although several features would suggest a fundamental role in pollination. A second related gene (SLR2) is conserved and expressed in a subset of Brassica genotypes. We analysed the stigmatic expression of SLR1 and SLR2 genes among 11 different plants from various species or genera of the Brassicaceae and examined the extent of the pollen-stigma interaction during intraspecific, interspecific and intergeneric pollinations between them. Appropriate statistical tests on these variables (pollen adhesion, germination, penetration into the stigma, style and ovary, and SLR gene expression) showed that expression of SLR1 (but not SLR2) may be a factor in pollen-stigma adhesion. This hypothesis was supported by the observation of reduced pollen-stigma adhesion in transgenic B. napus plants modified for SLR1 expression.