XVI International Botanical Congess

Spartina anglica arose around 1890 in Southern England, following hybridization between the indigenous S. maritima and the East-American introduced S. alterniflora. Chromosome doubling of the subsequent sterile hybrid S. x townsendii gave rise to the allopolyploid species S. anglica Hubbard, a vigorous clonal plant. We use RAPDs, RFLPs, nuclear and chloroplast DNA sequences to address the questions: Are all populations in France resulting from a single introduction? How is the allopolyploid genome evolving compared to its parents S. alterniflora and S. maritima? Our results are consistent with the propagation of one major clone in populations from Brittany, France, which is identical to the first generation hybrid S. x townsendii from Southern England. This genotype displays nuclear sequence additivity of both parental species and chloroplast DNA sequences identical to S. alterniflora, the maternal genome donnor. However, few new genotypes are encountered in some populations, suggesting that the allopolyploid is undergoing genomic changes.