Contrasting models of female reproductive tract in four o'clocks (Nyctaginaceae)

NORES, M. J.; LÓPEZ, H. L.; ANTON, A. M.; RUDALL, P.

AMERICAN JOURNAL OF BOTANY

BOTANICAL SOC AMER INC

Lugar: St. Louis; Año: 2015 vol. 102 p. 1026 - 1039

0002-9122

*Premise of the study: In angiosperms, several carpel tissues are specialized tofacilitate pollen-tube elongation to achieve fertilization. We evaluate the possibleevolutionary pathways of the diverse female reproductive tracts in Nyctaginaceae.*Methods: We perform an anatomical study of a range of species representing differenttribes, using light, fluorescence, scanning and transmission electron microscopy.*Key results: Stigmas have multicellular, multiseriate papillae, except Boerhavia diffusawith unicellular papillae. The styles are solid, with a strand of transmitting tissue linkingthe stigma with the ventral ovary wall. In Allionia, Boerhavia and Mirabilis, thetransmitting tissue branches into two independent tracts at the base of the ovary andcontinues across the lateral margins of the funicle to the micropyle; it is composed ofcells with thick walls surrounded by abundant extracellular matrix. Bougainvillea,Pisonia and Pisoniella have a diffuse transmitting tissue and an obturator, aproliferation of cells covered by a layer of secretory papillae that encloses the funicle,placenta and ventral wall of the gynoecium and contacts with the micropyle.*Conclusions: We propose two models of female reproductive tract, one in which anobturator is absent and the transmitting tissue is compact and branched (A), and one inwhich an obturator is present and the transmitting tissue is diffuse (B). Based oncharacter optimization, we hypothesize that model B represents the ancestral(plesiomorphic) condition in the family, and model A originated once during evolution,within the tribe Nyctagineae.