长萼兰花蕉(Orchidantha chinensis var.longisepala)气味腺结构探究

兰花蕉科(Lowiaceae)植物开花时,位于唇瓣的特殊腺体结构——气味腺(osmophores)能够产生和释放类似粪便的腐臭气味吸引传粉者。本研究以该科植物长萼兰花蕉(Orchidantha chinensis var.longisepala)为材料,采用中性红染色法初步确定气味腺的位置,然后用扫描电镜观察气味腺表皮细胞形态、透射电镜观察分泌细胞的超微结构。结果显示,散发腐臭气味的气味腺位于长萼兰花蕉唇瓣上端近轴面;气味腺由多样性的表皮细胞及表皮下1~2层分泌细胞构成,腺体细胞具有细胞核大、细胞质浓、线粒体和内质网丰富等特点;长萼兰花蕉花气味的释放主要依靠角质小泡的破裂完成,推测挥发性的小分子有助于花气味的释放。本研究结果有助于揭示兰花蕉科植物与传粉者之间的互作关系,了解植物的传粉过程。

Structural Analysis of the Osmophores in Orchidantha chinensis var. longisepala

Osmophores specialized and defined on the labellum of Lowiaceae plants can produce a strong scent, unpleasant to humans but attractive to pollinators, which mimics the odor of carrion or decaying fruit during anthesis. In the present study, the labellum of Orchidantha chinensis var. longisepala was stained in vivo with neutral red to ascertain the location of osmophores. We used scanning electron microscopy (SEM) to observe the morphology of epidermal cells and transmission electron microscopy (TEM) to explore the ultrastructure of secretory cells. Results showed that osmophores of O. chinensis var. longisepala were located at adaxial surface of the upper labellum. Diverse epidermal cells and 1-2 layers of secretory cells comprised the osmophores. Cells of the glandular tissue showed enlarged nuclei compared to cells of nearby tissue and a dense cytoplasm. These cells also have more endoplasmic reticulum, mitochondria and plastids, sometimes dictyosomes. The scent substances were mainly from rupturing outer layer of the cuticle, and the diffusion of small molecules may contribute to the release. Research on the osmophores of Lowiaceae is useful to reveal the interactions between plants and pollinators and study the process of pollination.