A highly conserved Brassica gene with homology to the S-locus-specific glycoprotein structural gene.

Abstract

The S-locus-specific glycoprotein of Brassica and the gene encoding it (the SLG gene) are thought to be involved in determining self-incompatibility phenotype in this genus. It has been shown that the Brassica genome contains multiple SLG-related sequences. We report here the cloning and characterization of a Brassica oleracea gene, SLR1, which corresponds to one of these SLG-related sequences. Like the SLG gene, SLR1 is developmentally regulated. It is maximally expressed in the papillar cells of the stigma at the same stage of flower development as the onset of the incompatibility response. Unlike SLG, the SLR1 genes isolated from different S-allele homozygotes are highly conserved, and this gene, which appears to be ubiquitous in crucifers, is expressed in self-compatible strains as well as self-incompatible strains. Most importantly, we show that the SLR1 gene is not linked to the S-locus and therefore cannot be a determinant of S-allele specificity in Brassica.

Identification of an S‐locus glycoprotein allele introgressed from B. napus ssp. rapifera to B. napus ssp. oleifera

“…The A35 cDNA was identical to 29-7 which belongs to a class of related genes termed SLR-7 locus (Lalonde et al, 1989). A second cDNA, A29, was very similar to showing approximately 94% homology at the DNA level.…”

“…The SLR-1 (Slocus related) and SLRP loci are present in all Brassica species, but they segregate independently of the S-locus and do not appear to be involved in the self-incompatibility reaction (Boyes et a/., 1991;Lalonde et al, 1989). The DNA sequence of SLR-2 is more closely related to the pollen-recessive SLGallele than to the SLR-1 gene (Boyes etal., 1991).…”

Pollen and Stigma Structure and Function: The Role of Diversity in Pollination

“…There is now extensive evidence that the proteins and lipids in the pollen coat, and proteins on the stigma surface, (Luu et al, 1999;Takayama et al, 2000). SLR1 is a stigma-expressed gene related to the S-locus glycoprotein, a protein involved in selfincompatibility (Lalonde et al, 1989). SLR1-mediated adhesion requires some time to establish itself, possibly to allow the mixing of stigma and pollen matrices; consequently, the strength of initial pollen binding in SLR1-deficient plants is the same as in wild-type plants (Luu et al, 1999).…”

The Self-Incompatibility Phenotype in Brassica Is Altered by the Transformation of a Mutant S Locus Receptor Kinase

“…This gene is also expressed in the stigma papilla cells (Stein et al, 1991;Goring and Rothstein, 1992). There are a variety of SRK -like genes in Brassica spp (Kumar and Trick, 1994) as well as genes similar to the SLG genes that have been shown to be unlinked to self-incompatibility (Lalonde et al, 1989). The functions of most of these genes are unknown, although the expression of one of these has been correlated with wound and pathogen response (Pastuglia et al, 1997).…”