Microsatellite Markers Confirm Self‐Pollination and Autogamy in Wild Populations of Vanilla mexicana Mill. (syn. V. inodora) (Orchidaceae) in the Island of Guadeloupe

The study aimed at evaluating the mating system of Vanilla mexicana (Orchidaceae) in natural populations in the island of Guadeloupe. A total of 132 V. mexicana samples were collected from 12 sites in Guadeloupe (Basse‐Terre). Five other samples coming from Martinique and Mexico completed our analyses. Reproductive biology experiments excluding pollinators with bagged flowers revealed 53.9% fruit set, a value identical to the natural fruit set measured in the populations. These results suggested that V. mexicana, unlike most Vanilla species, was reproducing by self‐pollination and autogamy. Due to lack of specific DNA markers for V. mexicana, microsatellite markers, previously developed in other Vanilla species, were used for the genetic analyses. Only 6 out of the 33 markers tested were transferable and polymorphic in V. mexicana. A panel of 51 V. mexicana samples genotyped with 3 polymorphic loci was finally retained for Guadeloupe population genetic analyses. A heterozygote deficiency was detected, and the selfing rate was estimated to 74%. These results confirmed the reproductive biology results as self‐pollination and autogamy were the most likely explanation for this deficit. Results were compared to those from allogamous wild Vanilla species and discussed in the light of suggested existence of a pollinator for V. mexicana in other areas (Mexico)

Biodiversity and evolution in the Vanilla genus

International audienceSince the publication of the first vanilla book by Bouriquet (1954c) and the more recent review on vanilla biodiversity (Bory et al., 2008b), there has been a world regain of interest for this genus, as witnessed by the recently published vanilla books (Cameron, 2011a; Havkin-Frenkel & Belanger, 2011; Odoux & Grisoni, 2010). A large amount of new data regarding the genus biodiversity and its evolution has also been obtained. These will be reviewed in the present paper and new data will also be presented. (Résumé d'auteur

Interesting traits in vanilla germplasm : Perspectives for breeding

International audienceno abstrac

Diversity and evolution of floral scent in the genus Vanilla.

International audiencePlants have developed mechanisms such as the release of volatile compounds by flowers to allow interactions with the environment and specifically with their pollinators. The evolution of floral scents in the genus Vanilla (Orchidaceae) is being tested by comparing floral scent profiles with the genus phylogeny (as obtained by nuclear ribosomal ITS sequencing) to assess if this trait is phylogenetically constrained and/or an adaptation to pollinators

Active sexual reproduction but no sign of genetic diversity in range-edge populations of Vanilla roscheri Rchb. f. (Orchidaceae) in South Africa

International audienceIn South Africa, the wild leafless Vanilla roscheri Rchb. f. (Orchidaceae) is distributed only on the banks of the Lake Sibaya in KwaZulu-Natal Coastal Forest in the iSimangaliso Wetland Park. It is the southernmost vanilloid orchid on the African continent and a species of high conservation priority with little understanding of its reproductive biology and levels of genetic diversity. Mating systems and pollination ecology of the species were assessed by in situ experiments, in addition to genotyping plants at 16 microsatellite markers. Allogamous but self-compatible, V. roscheri depends on pollinators to achieve sexual reproduction. Its natural fruit set (26.3 %) is the highest reported for a non-spontaneously self-pollinating Vanilla species. It was associated with numerous flower visitors including two female allodapine bees (Allodapula variegata and Allodape rufogastra, Xylocopinae), captured with pollinia stored on the hind legs, and one female anthophorine bee. On the other hand, we report an absence of genetic diversity and homozygosity of the South-African populations of V. roscheri for all the genetic markers. Given the preferential outbreeding, the high natural fruit set and the pollinator/visitor richness of V. roscheri in Sibaya, a high level of genetic diversity was expected, but this was not the case. We detected a counterintuitive situation between the results of reproductive biology and genetics, making sense once the population situation on the margins of the species distribution is included. The null diversity expressed through the homozygous monomorphic markers is a consequence of the range-edge localization of the populations, which may have been subjected to severe bottlenecks (due to long distance colonization or fragmentation) along with inbreeding, in the past. The analysis highlights the complementarity of the approaches for which the implications in terms of conservation of the species in South Africa are discussed

Nineteen polymorphic microsatellite markers from two african Vanilla species: across-species transferability and diversity in a wild population of V. humblotii from Mayotte

International audienceThere is a serious lack of information on the genetic diversity and population dynamics of the 110 tropical Vanilla species, although these are keys elements to adjust conservation strategies. Nineteen polymorphic microsatellite markers were developed from two African leafless Vanilla species V. roscheri and V. humblotii to use in population genetic studies. A transferability analysis of these markers on seven Vanilla species from various geographical origins was conducted. Nine microsatellites were polymorphic in a population of 22 individuals of V. humblotii from Mayotte (Comoros Archipelago). These markers had two to eight alleles per locus and observed heterozygosity ranged from 0.23 to 0.64. Amplification parameters were calibrated to facilitate multiplexing and rapid multi-loci genotyping. (Résumé d'auteur