Vanilla bahiana Hoehne (Orchidaceae): studies on fruit development and new perspectives into crop improvement for the Vanilla planifolia group

Abstract

Vanilla is the most well-known and economically important genus of Orchidaceae in the world. Vanilla bahiana is restricted to Brazil and its conservation status was recently assessed as ‘Endangered’. The species is phylogenetically closely related to V. planifolia, whose pods are the main natural source of vanillin. The primary desirable traits for vanilla production are high fruit set and great resistance to abiotic stress. High temperatures (> 32ºC) and heavy rain favor fungal infection, and thus are indirectly responsible for fruit drop by V. planifolia in cultivation. The aim of the present study was to follow the process of pod ripening of V. bahiana in a restinga fragment in an Environmental Protection Area of Bahia State, and to highlight implications for vanilla crop improvement. Fieldwork was carried out from April 2016 to January 2017. A total of nine manual self-pollinations and nine manual cross-pollinations were successfully carried out. Fruit length, diameter and girth were recorded every two weeks. Fruit permanence in the infrutescence was measured as consecutive days from pollination. Descriptive statistics were calculated and Pearson correlation analysis performed among all attributes per pollination method. The influence of temperature and rainfall was also analyzed. Pod measurements and fruit permanence in the infrutescence were higher for cross-pollination than self-pollination. Higher rainfall results in fruit drop. The use of V. bahiana in breeding efforts for the genus is here strongly suggested and supported by previously published studies that allowed us to highlight several desirable traits: vanillin production, its wide geographical distribution and occurrence in a variety of habitats; substantial populations; resistance to conditions of drought and high luminosity and temperature; extensive blooming period; high number of flowers per raceme; possible synchronised flowering with V. planifolia, and fruiting throughout the year. These prospects are promising and should be further evaluated, not only for V. bahiana but for other vanilla crop wild relatives. Studies of pollination ecology can be used to set guidelines for the conservation of the V. planifolia group and to encourage the development of strategies to increase the production of fruit and, consequently, vanillin for its culinary uses and medical applications.

Distribución espacial de Vanilla bahiana (Orchidaceae) en dos fitofisonomías de restinga. ¿El patrón espacial varía?

“…Las especies de Vanilla poseen semillas recalcitrantes y crustosas con endospermo, y posible dispersión zoocórica; abejas, murciélagos frugívoros y aves son sugeridos como agentes dispersantes de semillas en el género, además del viento asociado a la gravedad (Cameron & Chase, 1998;Householder et Distribución espacial de Vanilla bahiana al., 2010;Soto-Arenas & Dressler, 2010). Aunque se produce la maduración del fruto de V. bahiana en la APA Abaeté (Anjos et al, 2017;Nascimento et al, 2019), no se observan plántulas y la forma de dispersión de semillas en V. bahiana sigue siendo desconocida. Contrariamente a la percepción común, la dispersión de semillas de orquídeas por el viento ocurre en distancias cortas de menos de 10 metros (Murren & Ellison, 1998;Chung et al, 2004).…”

“…Recientemente, se ha sugerido el uso de V. bahiana en los esfuerzos de mejora genética del género Vanilla Mill., ya que la especie es filogenéticamente cercana a Vanilla planifolia Jacks. ex Andrews, la vainilla más importante económicamente, y tiene varios atributos ecológicos deseables, como gran cantidad de flores por racimo, extenso período de floración, fructificación durante todo el año y alta resistencia al estrés abiótico (Bouetard et al, 2010;Anjos et al, 2017;Nascimento et al, 2019). Además, V. bahiana produce cantidades significativas de vainillina, sustancia extraída de los frutos maduros y que es ampliamente utilizada en la gastronomía mundial e incluso en medicina (Bythrow, 2005;Lopes et al, 2019).…”

“…Sin embargo, V. bahiana ha sido evaluada como en peligro de extinctión dado que la mayoría de las poblaciones se encuentran en hábitats muy fragmentados (Ferreira et al, 2017). El conocimiento sobre distribuciones en microescalas y particularidades ecológicas de parientes silvestres de la vainilla es deficiente, incluso sobre V. bahiana, y necesario para que futuras acciones de conservación y programas de cultivo sostenible se establezcan de manera más adecuada (Nascimento et al, 2019;Watteyn et al, 2020).…”

Mammal‐mediated seed dispersal in Vanilla: Its rewards and clues to the evolution of fleshy fruits in orchids

“…Despite its economic importance, scientists have not yet elucidated why Vanilla fruits have peculiar traits that resemble those dispersed by animals. Vanilla is the most diverse genus among vanilloid orchids (approximately 100 species) (Cameron & Molina, 2006), and other Vanilla species represent potential sources of desirable traits for vanilla production (do Nascimento et al, 2019). However, there is a substantial degree of uncertainty regarding the natural history of Vanilla species, including the function of aromatic, fleshy fruits of certain species, which presumably plays a role in seed dispersal (Cameron & Molina, 2006).…”

Distribution and conservation of vanilla crop wild relatives: the value of local community engagement for biodiversity research

“…Xiong et al 2015;Havkin-Frenkel and Belanger 2018), and crop improvement programs are urgently needed. The wild relatives of the cultivated species Vanilla planifolia offer resources for diversifying the genetic base of natural vanilla cultivation (Maruenda et al 2013;Flanagan et al 2018;Nascimento et al 2019;Pérez-Silva et al 2021;da Silva Oliveira et al 2022), however, more research is needed in the exploration of these crop wild relatives.…”