Variation and evolutionary transformation of some characters of the pollinarium and pistil in Epidendroideae (Orchidaceae)

Mosquera-Mosquera, Hilda R.; Valencia-Barrera, Rosa María; Acedo, Carmen

doi:10.1007/s00606-019-01575-5

Cited by 13 publications

(14 citation statements)

References 94 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Here, we analyze the flower's mechanical barriers in two Oncidium Sw. species belonging to the subtribe Oncidiinae (Orchidaceae), which represents the most highly derived orchids of the New World (Dressler, 1993;Mosquera-Mosquera et al, 2019). Flowers of Oncidiinae (Figure 1) characteristically have large lips featuring so-called calli.…”

Section: Introductionmentioning

confidence: 99%

“Push and Pull”: Biomechanics of the Pollination Apparatus of Oncidium spp.

et al. 2021

View full text Add to dashboard Cite

Comprising ca. 28,000, species the Orchidaceae constitute one of the most species-rich plant families. Orchids differ from other monocotyledons i.a., in the formation of so-called pollinaria, which are entities consisting of pollen grains aggregated into compact pollinia and accessory structures, a viscidium and mostly also a pollinium stalk. The viscidium releases an adhesive material that attaches the pollinarium to a pollinator. Pollinaria are part of a complex pollination apparatus that enables the orchids to colonize niches in which only a few individuals of the respective pollinator occur infrequently. Because the aggregated pollen grains are removed from the flower at once, the development of a mechanical barrier ensuring that only suitable pollinators are able to access the flowers and more importantly to remove the pollen are important selective traits. In this paper we describe the functional morphology of the pollination apparatus in two orchid species, Oncidium wentworthianum and O. otogaya, by experimentally mimicking the pollination process. Furthermore, we analyzed the mechanical resistance of this apparatus by means of force measurements and showed that it most probably constitutes a hierarchical two-stage barrier. The first stage consists of the presence of the anther cap that not only protects the pollinia, but also serves to prevent premature removal of young and unripe pollinaria from the flower. As soon as the pollinaria are ripe, the anther cap sheds and the second stage of the mechanical barrier takes effect, a severable bond between pollinarium and rostellum. This bond can be overcome by a potential pollinator, applying a load of at least 10.8 mN (O. otogaya) or 12.6 mN (O. wentworthianum), respectively, on the viscidium which at the same time disengages the pollinarium from its anchorage. The adhesive material produced by the viscidium creates sufficient adhesive contact between pollinarium and pollinator. Potential pollinators, such as Centris spp. or Trigona spp. bees, should be well able to exert such forces by pushing their head/forebody into the orchid flowers. Thus, whether a pollinator is able to detach the pollinarium depends on both how forcefully it can push and how strongly it can pull the orchid pollination apparatus.

show abstract

Section: Introductionmentioning

confidence: 99%

“Push and Pull”: Biomechanics of the Pollination Apparatus of Oncidium spp.

et al. 2021

View full text Add to dashboard Cite

show abstract

“…The mechanics of the pollinia movement is possible due to the sophisticated orchid pollinarium, comprised of the pollinia and accessory structures. The viscidium, the sticky and viscous structure which adheres the pollinia to the pollinators' body , is diffuse and hydrophilic in Cyrtopodium (Mosquera-Mosquera et al 2019). The viscidium becomes amalgamated with the stigma, serving as support for the pollinia as they bend down.…”

Section: Discussionmentioning

confidence: 99%

“…The viscidium becomes amalgamated with the stigma, serving as support for the pollinia as they bend down. The tegular stipe (Mosquera-Mosquera et al 2019) keeps the pollinia hanging on the viscidium. Finally, the hard pollinia type of C. hatschbachii (Mosquera-Mosquera et al 2019) has elastoviscin, a sticky gumlike substance (Schill and Wolter 1986), which provides cohesion and allows it to get wet without liquefying or breaking apart.…”

Section: Discussionmentioning

confidence: 99%

“…The tegular stipe (Mosquera-Mosquera et al 2019) keeps the pollinia hanging on the viscidium. Finally, the hard pollinia type of C. hatschbachii (Mosquera-Mosquera et al 2019) has elastoviscin, a sticky gumlike substance (Schill and Wolter 1986), which provides cohesion and allows it to get wet without liquefying or breaking apart. These traits, together with the low degree of herkogamy, make the swinging movement of the pollinia and hence self-pollination possible.…”

Section: Discussionmentioning

confidence: 99%

“…In the Cypripedioideae, the pollen smears are loosely attached to the anther, without forming a true pollinarium . This is a much simpler structure when compared to the sophisticated pollinarium of the Epidendroidae with its several accessory structures (Mosquera-Mosquera et al 2019) and responsible to produce large hormonal quantities (Nair & Arditti 1991;. Still in the phylogeny, we may further ask if weight mediated resupination is present in both more derived and basal conditions, which could help us to understand the evolution of the phenomenon.…”

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Aspectos reprodutivos de orquídeas em ambientes de Vereda do Cerrado

Cardoso¹

View full text Add to dashboard Cite

The Veredas wetlands are unique environments in the Cerrado biome, harboring high diversity and providing important ecosystem services. These environments are particularly diverse in Orchidaceae. In this thesis, we study the reproductive biology of endangered orchids that occur in Veredas wetlands to demonstrate the diversity of processes and the potential for generating knowledge that these environments provide.Cyrtopodium hatschbachii is a species primarily pollinated by bees, but with low fruit set rates, which may even be null in some years. However, we demonstrate in the first chapter how herbivory and rainfall, two factors that are detrimental when considered separately, can together facilitate autogamy and promote reproductive assurance in this species.Phragmipedium vittatum is a lady's slippery orchid that traps pollinators in order to reproduce. In the second chapter, we demonstrate the various strategies that these flowers adopt to enable successful pollination, from pollinator capture, through the intrafloral movements they are forced to make, until pollen transfer during their exit from the flower.To do so, P. vittatum uses an aphid mimicry system that deceives gravid females of Syrphidae dipterans during flower entry and exit, as they are looking for oviposition sites where their aphidophagous larvae will feed on. Using also P. vittatum as model, we found that it is a unique species in the world as it presents intrapopulation variation in floral resupination. This process refers to the twist of approximately 180º that occurs in some flowers before or during anthesis, which makes them upside down. In the third chapter, we show that approximately 10% of the flowers in the population do not resupinate. We experimentally tested the role of resupination in the process of reproduction and found that only flowers with the lip facing downward have male and female reproductive success, when compared to flowers with the lip positioned upward and sideward. These results are important because they corroborate that the evolution of resupination is related 4 to pollination success, with the lip acting as a landing platform or trap and the column facing downward promoting precise pollen deposition. Finally, in the fourth chapter, we demonstrate that the probability of flowers failing to resupinate is negatively related to their weight. This is the first time that flower resupination has been demonstrated as being a weight dependent process. In short, these results show the diversity of life histories that these organisms threatened by extinction can tell us, as well as their potential for generating detailed knowledge. Thus, the conservation of these species and their respective environments is extremely important for the maintenance of such processes and interactions, which are certainly associated with an equilibrated environment that provides several ecosystem services.

show abstract