Abstract Detail

Systematics Section / ASPT

Joly, Simon [2], Doyle, Jane L. [1], Rauscher, Jason T. [4], Brown, A. H. D. [3], Doyle, Jeff J. [1].

Both concerted evolution and locus deletion have homogenized nrDNA loci in an allopolyploid species of Glycine (Leguminosae): Segregation data from an artificial cross..

In the allopolyploid species Glycine tomentella T1 (2n = 78), some individuals predominantly possess the 18S-5.8S-26S nuclear ribosomal gene (nrDNA locus) of one diploid parental species, G. tomentella D1 (2n = 38), whereas other individuals predominantly possess the repeat of the other parent, G. tomentella D3 (2n=40). Two mechanisms could account for this: deletion of a locus or interlocus concerted evolution. To discriminate between these two processes, T1 individuals possessing different nrDNA repeats were crossed and hybrids were selfed to obtain a segregating F2. Our results indicate that one parent retains two nrDNA loci mostly populated by D1 repeats whereas the other parent has a single major repeat populated with D3 repeats. Thus, it appears that both mechanisms--concerted evolution and locus loss--have occurred in the same allopolyploid species. These results should temper assumptions that the presence of only one homoeologous nrDNA locus in an allopolyploid can always be attributed to concerted evolution.

1 - Cornell University, L.H. Bailey Hortorium, Department of Plant Biology, Ithaca, New York, 14853, U.S.A.
2 - Université de Montréal, Institut de recherche en biologie végétale, 4101 rue Sherbrooke est, Montréal, Québec, H1X 2B2, Canada
3 - CSIRO Plant Industry, Centre for Plant Biodiversity Research, Canberra, Australian Capital Territory, , Australia
4 - Universidad de los Andes, Departamento de Ciencias Biológicas, Apartado Aéreo 4976, Bogotá, Cundinamarca, , Colombia

Keywords:
concerted evolution
allopolyploidy
gene loss
Glycine
nuclear ribosomal DNA.

Presentation Type: Poster
Session: 32-127
Location: Special Event Center (Cliff Lodge)
Date: Tuesday, August 3rd, 2004
Time: 12:30 PM
Abstract ID:266