Abstract

Natural populations of A. thaliana were found to exhibit polymorphisms in their SRK/SCR sequences, and to harbor hidden variation for expression of self-incompatibility, which can only be uncovered by transfer of A. lyrata SRK and SCR genes. Genetic and molecular analysis of this variability will allow, for the first time, a study of the genetics of inbreeding in natural populations of a genetically tractable species.

Issue

In crucifers, two genes, which encode the S-locus receptor kinase SRK and its ligand the S-locus cysteine-rich peptide SCR, function together to prevent self-pollination.. They are also responsible for the self-incompatible mode of mating.

The self-fertile model plant Arabidopsis thaliana can be rendered self-incompatible by transfer of these two genes from self-incompatible A. lyrata.

The major goal of the proposed study is to identify and characterize the genes underlying evolutionary switches from obligate out-breeding to self-fertility, and thus understand a major process in the reproductive isolation of plant species.

Response

A large number of geographical accessions of Arabidopsis thaliana are being screened by transformation with the A. lyrata SRK and SCR genes. The expression of the self-incompatibility trait is being investigated by microscopic, molecular, and genetic methods.

Impact

The study is expected to provide insight into the changes in mating system that occur during or subsequent to speciation, further our understanding of the molecular mechanism of self-incompatibility, and possibly reveal the evolutionary origins of self-incompatibility and its genes. In the long term, the project should also enhance the ability of breeders to manipulate plant reproduction for crop improvement.

Funding Sources

• Other Federal non-USDA (e.g., NSF, NIH, DOA, DOD)

Key Personnel

• Mikhail Nasrallah, Plant Biology
• June Nasrallah, Plant Biology
• Pei Liu, Plant Biology
• Nathan Boggs, Plant Biology,