Plant, Animal & Microbe Genomes X Conference

January 12-16, 2002
Town & Country Convention Center
San Diego, CA

Workshop: Apomixis
            

CLONAL LONGEVITY, GENE FLOW AND CONVERGENT ANEUPLOIDY: KEYS TO SUCCESS IN THE APOMICTIC ARABIS HOLBOELLII COMPLEX.

¹ Department of Genetics and Evolution, Max Planck Institute for Chemical Ecology, Carl Zeiss Promenade 10, Jena, 07745, Germany

The Arabis holboellii complex is part of the North American Brassicaceae, members of which can reproduce via sex or apomixis. Previous studies have shown sexual individuals to be diploid, while apomictic individuals can be diploid (and aneuploid) or polyploid (typically 3n). We have analyzed ploidy, chloroplast SNP and INDEL polymorphisms, and microsatellite variation in over 400 accessions of A. holboellii and A. drummondii from western North American and Greenland. Polyploidy and apomixis expression have been repeatedly evolved in this complex, and gene flow between apomicts and sexual individuals has led to high levels of clonal variability. Interestingly, aneuploidy for two different chromosomes has been convergently attained in different haplotypes, a reflection of assortative selection acting on ploidy variants. Our data on clone distribution, ploidy evolution and relative clonal age thus provide a framework upon which we are studying the different selective pressures acting upon male and female function during flower and seed development. Taken together, our data imply that Arabis holboellii appears to have some predisposition for the evolution of apomictic reproduction.