Résumé
Characterisation and evaluation of coconut populations, based on morphological and agronomic traits is time-consuming, labour-intensive and subject to environmental effects. Some 1200 accessions are recognised by the International Coconut Genetic Resources Network (COGENT) and they plan to collect threatened and useful germplasm to augment the collections, with a view to establishing regional gene-banks. Therefore, sensitive and reliable techniques for assessing genetic diversity and screening agronomic traits are necessary to establish effective collecting and gene-banking strategies. A set of 37 highly polymorphic microsatellite markers were isolated from a small-insert microsatellite-enriched library of the cultivar Tagnanan Tall (Rivera et al., 1999. Genome 42:668-675). In a recent study, 31 individuals from 14 coconut populations across the entire geographic range were tested with the microsatellite markers and 339 alleles were detected (Teulat et al., 1999. Theoretical and Applied Genetics, in press). Generally, diversity was higher in populations from the South Pacific and South East Asia. Three microsatellite loci gave distinct genotypes for all but two populations. East African populations had higher heterozygosities than those from West Africa, and the populations from Tonga and Fiji had distinct alleles from those of the South Pacific. AFLP analysis with 12 primer combinations produced similar relationships and were also in agreement with previous RFLP results obtained with the same material (Lebrun et al., 1998. Euphytica 101:103-108). In collaboration with five European laboratories, we have embarked on a genome mapping project using AFLPs, microsatellites, RFLPs and ISTR markers. Preliminary results from this work will also be discussed. (Texte intégral)