Phenotypic plasticity of floral volatiles in response to increasing drought stress
Phenotypic plasticity of floral volatiles in response to increasing drought stress
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DOI：
10.1093/aob/mcy193
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发表时间：
2019-03-14
期刊：
影响因子：
4.2
通讯作者：
Raguso, Robert A.
中科院分区：
文献类型：
--
作者：
Campbell, Diane R.;Sosenski, Paula;Raguso, Robert A.
背景和目的花朵释放出广泛的挥发性化合物，这些化合物对与传粉者或草食动物的相互作用至关重要。然而，关于环境如何影响植物挥发物的研究大多集中在叶片排放上，对花挥发性物质变异的非生物来源知之甚少。随着全球气温的升高以及干旱频率和严重程度的变化，了解花挥发性排放中的表型可塑性变得越来越重要。方法对亚高山草本植物麦冬及其近缘杂交种的植株进行渐进式干燥处理，模拟田间土壤水分的变化范围。在干旱期间的4个时间点测定了花的挥发物和叶片气体交换。关键结果是，随着土壤的干燥，花的挥发物排放总体上增加，成分发生了变化，从更多的1，3-辛二烯和苯甲醇到更高的代表某些萜类。单个化合物的排放量与土壤中的体积含水率没有线性关系。当土壤水分处于中等水平时，占主导地位的化合物单萜烯-蒎烯在香气混合物中所占比例最高。相反，倍半萜(E，E)-法尼烯的释放随着干旱的加剧而加速。花卉挥发物的变化没有跟踪到光合作用速率或气孔导度变化的时间进程。结论本研究显示了特定的花卉挥发性有机化合物对土壤水分的响应。此外，这些非线性反应还表明，极端干旱可能会产生温和干旱无法预测的影响。随着落基山脉初夏的干旱，以及随着积雪融化逐渐提早，花卉挥发物可能会随着季节的变化而变化。水可获得性的变化可能会对植物-动物之间的相互作用产生影响，这种相互作用是通过花的挥发物的非线性变化来调节的。
Background and Aims Flowers emit a wide range of volatile compounds which can be critically important to interactions with pollinators or herbivores. Yet most studies of how the environment influences plant volatiles focus on leaf emissions, with little known about abiotic sources of variation in floral volatiles. Understanding phenotypic plasticity in floral volatile emissions has become increasingly important with globally increasing temperatures and changes in drought frequency and severity. Here quantitative relationships of floral volatile emissions to soil water content were analysed.Methods Plants of the sub-alpine herb Ipomopsis aggregata and hybrids with its closest congener were subjected to a progressive dry down, mimicking the range of soil moistures experienced in the field. Floral volatiles and leaf gas exchange were measured at four time points during the drought.Key Results As the soil dried, floral volatile emissions increased overall and changed in composition, from more 1,3-octadiene and benzyl alcohol to higher representation of some terpenes. Emissions of individual compounds were not linearly related to volumetric water content in the soil. The dominant compound, the monoterpene -pinene, made up the highest percentage of the scent mixture when soil moisture was intermediate. In contrast, emission of the sesquiterpene (E,E)--farnesene accelerated as the drought became more intense. Changes in floral volatiles did not track the time course of changes in photosynthetic rate or stomatal conductance.Conclusions This study shows responses of specific floral volatile organic compounds to soil moisture. The non-linear responses furthermore suggest that extreme droughts may have impacts that are not predictable from milder droughts. Floral volatiles are likely to change seasonally with early summer droughts in the Rocky Mountains, as well as over years as snowmelt becomes progressively earlier. Changes in water availability may have impacts on plant-animal interactions that are mediated through non-linear changes in floral volatiles.