Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560 012, India.
J Chem Ecol. 2013 May;39(5):630-42. doi: 10.1007/s10886-013-0280-5. Epub 2013 Apr 23.
Plants produce volatile organic compounds (VOCs) in a variety of contexts that include response to abiotic and biotic stresses, attraction of pollinators and parasitoids, and repulsion of herbivores. Some of these VOCs may also exhibit diel variation in emission. In Ficus racemosa, we examined variation in VOCs released by fig syconia throughout syconium development and between day and night. Syconia are globular enclosed inflorescences that serve as developing nurseries for pollinating and parasitic fig wasps. Syconia are attacked by gallers early in their development, serviced by pollinators in mid phase, and are attractive to parasitoids in response to the development of gallers at later stages. VOC bouquets of the different development phases of the syconium were distinctive, as were their day and night VOC profiles. VOCs such as α-muurolene were characteristic of the pollen-receptive diurnal phase, and may serve to attract the diurnally-active pollinating wasps. Diel patterns of release of volatiles could not be correlated with their predicted volatility as determined by Henry's law constants at ambient temperatures. Therefore, factors other than Henry's law constant such as stomatal conductance or VOC synthesis must explain diel variation in VOC emission. A novel use of weighted gene co-expression network analysis (WGCNA) on the volatilome resulted in seven distinct modules of co-emitted VOCs that could be interpreted on the basis of syconium ecology. Some modules were characterized by the response of fig syconia to early galling by parasitic wasps and consisted largely of green leaf volatiles (GLVs). Other modules, that could be characterized by a combination of syconia response to oviposition and tissue feeding by larvae of herbivorous galler pollinators as well as of parasitized wasps, consisted largely of putative herbivore-induced plant volatiles (HIPVs). We demonstrated the usefulness of WGCNA analysis of the volatilome in making sense of the scents produced by the syconia at different stages and diel phases of their development.
植物在各种情况下会产生挥发性有机化合物（VOCs），包括对非生物和生物胁迫的反应、吸引传粉者和寄生蜂，以及排斥食草动物。其中一些 VOCs 的排放也可能存在昼夜变化。在榕属植物中，我们研究了榕果在整个榕果发育过程中以及白天和夜间释放的 VOCs 的变化。榕果是球形的封闭花序，作为传粉和寄生榕蜂的发育苗圃。榕果在早期发育阶段会受到瘿蜂的攻击，在中期会被传粉者服务，在后期发育阶段会受到瘿蜂的吸引。不同发育阶段的榕果的 VOC 花束是独特的，它们的白天和夜间 VOC 图谱也是独特的。α-穆勒烯等 VOC 是花粉接受的白天阶段的特征，可能有助于吸引白天活动的传粉蜂。挥发性物质释放的昼夜模式不能与其在环境温度下通过亨利定律常数预测的挥发性相关联。因此，除了亨利定律常数之外的因素，如气孔导度或 VOC 合成，必须解释 VOC 排放的昼夜变化。对挥发组学进行加权基因共表达网络分析（WGCNA）的一种新用途导致了七个不同的共挥发物模块，可以根据榕果的生态学进行解释。一些模块的特点是榕果对寄生蜂早期瘿蜂的反应，主要由绿叶挥发物（GLVs）组成。其他模块的特点是榕果对产卵和幼虫取食组织的反应，以及寄生蜂的取食，主要由潜在的食草性诱导植物挥发物（HIPVs）组成。我们证明了 WGCNA 分析挥发组学在理解榕果在不同发育阶段和昼夜阶段产生的气味方面的有用性。
