Vanilla bicolor Lindl. (Orchidaceae) from the Peruvian Amazon: auto-fertilization in Vanilla and notes on floral phenology

Abstract

Minimal documentation exists for natural pollination in wild Vanilla spp., despite the economic importance of this genus, additionally commercial vanilla (V. planifolia Jacks.) is one of very few crops whose production depends entirely on artificial pollination. Flowering and fruiting phenology of Vanilla bicolor Lindl., a close relative of V. planifolia, was documented in a palm swamp in the Peruvian Amazon. V. bicolor was found to autofertilize via bagging experiments. This ecotype had an average fruit set per raceme of 42.50 ± 2.5%. Pollen removal experiments suggest that stigmatic leak may be the mechanism by which auto-pollination occurs in V. bicolor.

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

“…Indeed, V. edwallii, from subgenus Vanilla, V. parviflora group, is not capable of self-pollination and requires a pollinator, supposedly the bee Epicharis (Hoplepicharis) affinis [32]. Autogamy in V. bicolor was explained by stigmatic fluids [28,31], and agamospermy was ruled out [31]. For V. palmarum, both a narrow rostellum [4] and stigmatic leak [28] were noted.…”

Biodiversity and Evolution in the Vanilla Genus

“…Also all fertilized flowers showed fully developed rostellum. This suggested that a stigmatic leak, where stigma lobes release a fluid that contacts the pollen and induces germination of the pollen tubes (Van Der Pijl & Dodson, 1966) was the more likely explanation for self-pollination in this species (Van Dam et al, 2010). The observation of the occurrence of a thick rostellum in V. palmarum led to the suggestion of an identical mechanism .…”

“…A few Vanilla species are described as spontaneously self-pollinating Soto Arenas & Cameron, 2003;Soto Arenas & Dressler, 2010;Van Dam et al, 2010), as suggested by their abnormally high fruit set (table 1). This is consistent with general data in orchids showing that autogamous species display a much higher fruit set (77%) than cross pollinating species for which the majority show fruit set <20% (Tremblay et al, 2005 More precise observations are available for some of these species.…”

“…The lack of observed local pollinators and the high fruit set also suggested that V. bicolor and V. palmarum were self-pollinating species in Peru . Two mechanisms were proposed to account for self-pollination in Vanilla species (Van Dam et al, 2010): true self-pollination occurring by either stigmatic leak and/or the presence of a dehydrated or reduced rostellum, or agamospermy. In V. bicolor, pollen removal experiments showed that agamospermy was not the mechanism in play (Van Dam et al, 2010).…”

An integrated strategy for the conservation and sustainable use of native Vanilla species in Colombia

“…Pollination in many aromatic species is likely undertaken by male Euglossine bees (Soto-Arenas 2003, Pansarin 2016). Within the aromatic clade, Roubik and Ackerman (1987) (Householder et al 2010;Van Dam et al 2010), and some spontaneous self-pollination may occur in V. planifolia (Soto-Arenas 2003). In Cuba, where no Euglossine bees are present (Genaro 2008), naturalized populations of Vanilla planifolia present natural pollination events.…”