Résumé
Taro (Colocasia esculenta (L.) Schott) is widely distributed in tropical
and sub-tropical areas. However, its origin, diversification and dispersal
remain unclear. While taro genetic diversity has been documented at the
country and regional levels in Asia and the Pacific, few reports are
available from Americas and Africa where it has been introduced through
human migrations. We used eleven microsatellite markers to investigate the
diversity and diversification of taro accessions from nineteen countries
in Asia, the Pacific, Africa and America. The highest genetic diversity
and number of private alleles were observed in Asian accessions, mainly
from India. While taro has been diversified in Asia and the Pacific mostly
via sexual reproduction, clonal reproduction with mutation appeared
predominant in African and American countries investigated. Bayesian
clustering revealed a first genetic group of diploids from the
Asia-Pacific region and to a second diploid-triploid group mainly from
India. Admixed cultivars between the two genetic pools were also found. In
West Africa, most cultivars were found to have originated from India. Only
one multi-locus lineage was assigned to the Asian pool, while cultivars in
Madagascar originated from India and Indonesia. The South African
cultivars shared lineages with Japan. The Caribbean Islands cultivars were
found to have originated from the Pacific, while in Costa Rica they were
from India or admixed between Indian and Asian groups. Taro dispersal in
the different areas of Africa and America is thus discussed in the light
of available records of voyages and settlements.