Multi-disciplinary approach of Tahitian vanilla biodiversity assessment

Three vanilla species are cultivated in the world: V. planifolia, V. pompona and V. tahitensis. Tahitian vanilla is characterized by anise notes [1] and oily texture. Its diversification seems to have occurred in French Polynesia since its introduction and despite its vegetative mode of propagation [2]. Vanilla growers distinguish about twenty cultivars according to their morphological traits but in local farms, two cultivars are mainly produced: „Tahiti“ and „Hapape“. More than two hundred plants have been collected in the Polynesian islands and grown in a preservation shade house.

Tahitian vanilla biodiversity is investigated using morphological, genetic, aromatic and lipidic traits. To assess genetic diversity, fingerprints (AFLP) and chromosome counts were realized. The chemical composition of the pods was investigated by HPLC analysis of aromatic compounds and fatty acids. Many morphological traits were also measured.

We report here the results of the diversity characterization of five cultivars which were chosen for their large variation in morphological traits. The five cultivars show differences in their fingerprints and/or in their diploidy level. Moreover, they are well discriminated by their aroma and fatty acid compositions. The two most distinct cultivars, according to their genetic pattern, also present the most divergent chemical compositions.

Such a combined analysis may provide useful information for breeding programs by allowing i) the selection of the best cultivars according to their aromatic and fatty acid composition, ii) the identification of genes related to the flavor and fatty acid biosynthesis for the selection of the best hybrids.

References: [1] Da Costa, C. et al (2006) Dev. Food Sci. 43:161–164.

[2] Duval, M.F. et al. (2006) Les Actes du BRG 6:181–196.