FERRUCCI maria silvia
Structure and development of anthers and connective glands in two species of Stigmaphyllon Malpighiaceae): are heteromorphic anthers related to division of labour?
AVALOS A.A.; TORRETTA, J.P.; LATTAR E.C.,; FERRUCCI, MARÍA SILVIA
Lugar: Viena; Año: 2020 p. 1165 - 1181
Abstract. Heteranthery has been largely associatedwith a division of labour between anthers. Most species of Stigmaphyllon (Malpighiaceae) present heteromorphic anthers andglandular connectives of different development; yet, the functional meaning ofthis condition has never been explored in the genus. The aims of this studywere to provide a comparative description of the structure and development ofanthers and their connective glands in S.bonariense and S. jatrophifoliumand to assess the existence of division of functions. Natural populations wereselected to collect flowers at different stages. Anthers were subjected tomorpho-anatomical, histochemical and pollen viability studies. For bothspecies, abundance of pollen grains and size of anther and their connectiveglands were estimated. Three types of stamens are recognized: stamen withsmall, intermediate and large anthers. Anthers of both species exhibit asimilar glandular tissue in the connective, and the histochemical analysisrevealed that it produce a mucilagous secretion. The pattern of anther walldevelopment, stainability and release of pollen grains was identical amonganther types. For both species, we observed a positive relationship betweenanther size and abundance of pollen grains, but an inverse relationship betweenarea of anthers and size (area and thickness) of connective glands in smallanthers vs. intermediate and large ones. Our results evidence a specializationof anthers related to division of labour between heteromorphic stamens in twospecies of Stigmaphyllon. Thus, oneset of anthers produces large amount of pollen grains for pollination and anothersets large quantities of mucilage, which would improve pollen transport (betteradherence to pollinator body and dampness maintenance). Nevertheless,heteranthery in both Stigmaphyllonspecies would represent a transitional state towards the division of labourrather than a stable state.