Canaveze Yve, Guimarães Elza, Machado Silvia Rodrigues
Centro de Ciências Biológicas e da Saúde (CCBS), Departamento de Botânica, Universidade Federal de São Carlos (UFSCar), São Carlos, 13565-905, SP, Brazil.
Instituto de Biociências, Departamento de Biodiversidade e Bioestatística, Universidade Estadual Paulista (UNESP), Botucatu, 18618‑970, SP, Brazil.
J Plant Res. 2025 May 29. doi: 10.1007/s10265-025-01648-2.
Floral glands, which produce diverse metabolites, have become the focus of increasing interest because of their important roles in plant-animal interactions. The glands in the receptacle of Pseudobombax longiflorum (Malvaceae) are widely accepted as nectaries. Using light, scanning, and transmission electron microscopy, we studied the anatomy, histochemistry, ultrastructure, and secretory dynamics of the receptacle glands in this species. The glands were active in secretion from young flower buds to immature fruits. Trigona spinipes was the most abundant and frequent visitor. The glands were composed of a uniseriate epidermis covered with a thick cuticle and a multilayered parenchyma, exhibiting two subregions with abundant phloem in the innermost region. These glands produced sugars, resins, oils, and phenolic compounds. Glandular cells exhibited large nuclei with nucleoli, polymorphic plastids with lipophilic inclusions, numerous mitochondria, endoplasmic reticulum profiles, cytoplasmic oil bodies, and vacuoles containing phenolic compounds. Plasmodesmata indicate that secretory components are transported from cell to cell via the symplast. There is also evidence for granulocrine and eccrine secretion mechanisms. The accumulated secretions form a bulge in the central region of the gland. The bulged epidermis detached from the parenchyma cells, and the rupture of the epidermal cells released the accumulated hydrophilic components. Residual lipophilic secretions were embedded in the epidermal cell wall and cuticle. The receptacle glands of P. longiflorum are not typical nectaries but mixed glands that produce both hydrophilic and lipophilic secretions during floral development until young fruits.
能产生多种代谢产物的花腺，因其在植物与动物相互作用中的重要作用，已成为越来越受关注的焦点。长花假木棉（锦葵科）花托上的腺体被广泛认为是蜜腺。我们利用光学显微镜、扫描电子显微镜和透射电子显微镜，研究了该物种花托腺体的解剖结构、组织化学、超微结构和分泌动态。这些腺体从幼花芽到未成熟果实阶段都处于活跃分泌状态。刺蜂是最常见且频繁光顾的访客。腺体由覆盖着厚角质层的单层表皮和多层薄壁组织组成，在最内层区域有两个富含韧皮部的亚区域。这些腺体产生糖类、树脂、油脂和酚类化合物。腺细胞具有带核仁的大细胞核、含有亲脂性内含物的多型质体、大量线粒体、内质网轮廓、细胞质油体以及含有酚类化合物的液泡。胞间连丝表明分泌成分通过共质体在细胞间运输。也有证据表明存在颗粒分泌和局部分泌机制。积累的分泌物在腺体中央区域形成一个凸起。凸起的表皮与薄壁组织细胞分离，表皮细胞破裂释放出积累的亲水性成分。残留的亲脂性分泌物嵌入表皮细胞壁和角质层中。长花假木棉的花托腺体不是典型的蜜腺，而是在花发育直至幼果阶段产生亲水性和亲脂性分泌物的混合腺体。
