Pollen and stigma morphology of some Phaseoleae species (Leguminosae) with different pollinators

Abstract

Pollen transport to a receptive stigma can be facilitated through different pollinators, which submits the pollen to different selection pressures. This study aimed to associate pollen and stigma morphology with zoophily in species of the tribe Phaseoleae. Species of the genera Erythrina, Macroptilium and Mucuna with different pollinators were chosen. Pollen grains and stigmas were examined under light microscopy (anatomy), scanning electronic microscopy (surface analyses) and transmission electronic microscopy (ultrastructure). The three genera differ in terms of pollen wall ornamentation, pollen size, pollen aperture, thickness of the pollen wall, amount of pollenkitt, pollen hydration status and dominant reserves within the pollen grain, while species within each genus are very similar in most studied characteristics. Most of these features lack relationships to pollinator type, especially in Erythrina and Mucuna. Pollen reserves are discussed on a broad scale, according to the occurrence of protein in the pollen of invertebrate- or vertebrate-pollinated species. Some pollen characteristics are more associated to semi-dry stigma requirements. This apical, compact, cuticularised and secretory stigma occurs in all species investigated. We conclude that data on pollen and stigma structure should be included together with those on floral morphology and pollinator behaviour for the establishment of functional pollination classes.

Reproductive versatility in legumes: the case of amphicarpy in Trifolium polymorphum

“…Selfpollination is also hindered by the presence of a stigmatic cuticle that prevents early pollen germination on the stigma before anthesis (Speroni et al 2012). This feature, common in entomophilous and self-compatible legumes (Heslop-Harrison & Heslop-Harrison 1983;Small 1986;Bruneau & Anderson 1988;De las Heras et al 2001;Galloni et al 2007;Etcheverry et al 2008;Sahai 2009;Basso-Alves et al 2011), is associated with 'tripping' pollination, where mechanical pollinator action is needed to break down the cuticle, allowing pollen grain adhesion and germination (Frankel & Galum 1977). Therefore, T. polymorphum aerial flowers present a mixed mating system (MMS), the most common system found in flowering plants (ca.…”

Morphological diversity and function of the stigma in Ficus species (Moraceae)

“…Although the function of the stigma is the same for all angiosperms, stigma structure (shape, cellular composition and secretion occurrence) and physiology are very diverse (Edlund et al, 2004;Endress, 1994;Heslop-Harrison, 1992). The shape of the stigma, for example, may be of taxonomic value (Bigazzi and Selvi, 2000;Brown and Gilmartin, 1989;Heslop-Harrison, 1981), in addition to being related to adaptations to pollen grain deposition, such as the plumose stigma in the anemophilous species of Poaceae (Heslop-Harrison, 1992), or requiring the visit/manipulation 3 of an animal to become receptive to pollen germination (Basso-Alves et al, 2011;Sigrist and Sazima, 2004).…”

“…However, much greater effort has been expended on elucidating the relationship between pollen and pollination (e.g., Banks and Rudall, 2016;Hesse, 2000;Osborn et al, 1991) than between stigma and pollination (Heslop-Harrison, 1992). The study of the diversity of stigmata related to various types of pollination (Basso-Alves et al, 2011;Jousselin and Kjellberg, 2001) and breeding systems (Katinas et al, 2016;Lora et al, 2011) is thus of great interest in general and for obligate mutualisms such as between fig trees (Ficus) and their agaonid pollinating wasps in particular (Galil and Eisikowitch, 1968).…”

Elucidating the unusual floral features ofSwartzia dipetala(Fabaceae)

“…This hypothesis has been supported in studies of Cassiinae (Fabaceae) (Tucker, ), but there have been few detailed investigations of pollen grains in Fabaceae (e.g. Cowan, ; Ferguson & Skvarla, ; Moço & Pinheiro, ; Teixeira, Forni‐Martins & Ranga, ; Agostini et al ., ; Basso‐Alves, Agostini & Teixeira, ).…”