Universidad Nacional del Nordeste/CONICET, Instituto de Botánica del Nordeste (IBONE), Sargento Juan Bautista Cabral 2131, W3402BKG, Corrientes, Argentina.
Universidad Nacional de Salta/CONICET, Facultad de Ciencias Naturales, Laboratorio de Investigaciones Botánicas (LABIBO), Av. Bolivia 5150, A4400, Salta, Argentina.
An Acad Bras Cienc. 2021 Dec 8;93(suppl 4):e20201401. doi: 10.1590/0001-3765202120201401. eCollection 2021.
Floral nectaries are essential for plant reproduction but little is known about the relationship between these secretory structures and pollination system in cacti. To test phenotypic patterns in nectaries associated with pollination syndromes and/or with its pollinators, we selected from evolutionarily related genera Cleistocactus, Denmoza, and Echinopsis, a set of species with bird-pollinated flowers and floral traits that may fit with ornithophily or with sphingophily, and other set of sphingophilous species with moths as effective pollinator. Observations were made under light microscope and scanning and transmission electron microscopes. Nectaries are located at the base of the filaments welded to the tube, forming a chamber. The nectary consists of the epidermis with distinctive features in each genus, a secretory parenchyma which may be vascularized and a non-secretory vascularized parenchyma. Anatomical variants observed in nectaries of different species are not consistent with the floral pollination syndromes neither with groups of pollinators. The basic structure of the nectar chamber is relatively conserved, a fact that may be explained by phylogenetic conservatism among the genera investigated. Our results revalue the role of anatomical traits for the systematics of Cactaceae.
花蜜腺对于植物繁殖至关重要，但关于仙人掌类植物中这些分泌结构与传粉系统之间的关系，我们知之甚少。为了测试与传粉综合征和/或其传粉者相关的蜜腺的表型模式，我们从进化上相关的属中选择了一组具有鸟类传粉花和可能适合鸟类传粉或鳞翅目传粉的花部特征的物种，以及另一组蛾类作为有效传粉者的鳞翅目传粉物种。观察是在光学显微镜、扫描电子显微镜和透射电子显微镜下进行的。蜜腺位于与管焊接的花丝基部，形成一个腔室。蜜腺由表皮组成，每个属都有独特的特征，分泌薄壁组织可能有血管化，还有非分泌的血管化薄壁组织。在不同物种的蜜腺中观察到的解剖变体与花的传粉综合征或传粉者群体不一致。不同物种蜜腺的基本结构相对保守，这一事实可能是由于所研究属之间的系统发育保守性所致。我们的结果重新评估了解剖特征在仙人掌科系统发育中的作用。
