Gonçalves-Souza Patrícia, Schlindwein Clemens, Dötterl Stefan, Paiva Elder Antônio Sousa
Departamento de Botânica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, MG, Brazil and.
Department of Ecology and Evolution, Plant Ecology, University of Salzburg, 5020 Salzburg, Austria.
Ann Bot. 2017 Mar 1;119(4):533-543. doi: 10.1093/aob/mcw236.
Araceae species pollinated by nocturnal Cyclocephalini beetles attract their pollinators by inflorescence scents. In Philodendron , despite the intense odour, the osmophores exhibit no definite morphological identity, making them difficult to locate. This may explain why structural studies of the scent-releasing tissue are not available so far.
Several approaches were employed for locating and understanding the osmophores of Philodendron adamantinum . A sensory test allowed other analyses to be restricted to fertile and sterile stamens as odour production sites. Stamens were studied under light and electron microscopy. Dynamic headspace and gas chromatography-mass spectrometry were used to collect and analyse scents from different zones of the inflorescence.
The epidermal cells of the distal portion of fertile stamens and staminodes are papillose and, similar to the parenchyma cells of this region, have dense cytoplasm and large nuclei. In these cells, the composition of organelles is compatible with secretory activity, especially the great number of mitochondria and plastids. In this portion, lipid droplets that are consumed concomitantly with the release of odour were observed. Quantitative scent analyses revealed that the scent, with a predominance of dihydro-β-ionone, is mainly emitted by the fertile and sterile staminate zones of the spadix. An amorphous substance in the stomata pores indicates that the components are secreted and volatilized outside of the osmophore under thermogenic heat.
Despite the difficulty in locating osmophores in the absence of morphological identity and inefficiency of neutral red staining, the osmophores of P. adamantinum have some features expected for these structures. The results indicate a functional link between thermogenesis and volatilization of osmophore secretions to produce olfactory signals for attracting specialized beetle pollinators. These first experimental data about the precise location of osmophores in Philodendron will stimulate studies in related species that will allow future comparison and the establishment of patterns of functional morphology.
由夜行性Cyclocephalini甲虫授粉的天南星科植物通过花序气味吸引传粉者。在喜林芋属植物中，尽管气味浓烈，但气味腺没有明确的形态特征，难以定位。这或许可以解释为何迄今为止尚未有关于气味释放组织的结构研究。
采用多种方法来定位和了解硬叶喜林芋的气味腺。感官测试使其他分析能够局限于作为气味产生部位的可育和不育雄蕊。在光学显微镜和电子显微镜下对雄蕊进行研究。使用动态顶空和气相色谱 - 质谱联用技术收集和分析来自花序不同区域的气味。
可育雄蕊和退化雄蕊远端部分的表皮细胞呈乳头状，与该区域的薄壁细胞相似，具有浓密的细胞质和大的细胞核。在这些细胞中，细胞器的组成与分泌活动相符，尤其是大量的线粒体和质体。在这部分区域，观察到与气味释放同时消耗的脂滴。定量气味分析表明，以二氢-β-紫罗兰酮为主的气味主要由肉穗花序的可育和不育雄花区域释放。气孔孔中的无定形物质表明这些成分在产热作用下在气味腺外部分泌并挥发。
尽管在缺乏形态特征以及中性红染色效率不高的情况下难以定位气味腺，但硬叶喜林芋的气味腺具有这些结构所预期的一些特征。结果表明产热与气味腺分泌物挥发之间存在功能联系，以产生吸引特定甲虫传粉者的嗅觉信号。这些关于喜林芋属植物中气味腺精确定位的首批实验数据将激发对相关物种的研究，以便未来进行比较并建立功能形态模式。
