Institute of Plant Sciences, University of Bern, 3013, Bern, Switzerland.
Department of Biochemistry, Max Planck Institute for Chemical Ecology, 07745, Jena, Germany.
Plant Cell Environ. 2019 Jun;42(6):1950-1963. doi: 10.1111/pce.13532. Epub 2019 Mar 28.
Volatile organic compounds (VOCs) emitted by plant leaves can influence the physiology of neighbouring plants. In contrast to leaf VOCs, little is known about the role of root VOCs in plant-plant interactions. Here, we characterize constitutive root VOC emissions of the spotted knapweed (Centaurea stoebe) and explore the impact of these VOCs on the germination and growth of different sympatric plant species. We show that C. stoebe roots emit high amounts of sesquiterpenes, with estimated release rates of (E)-β-caryophyllene above 3 μg g dw hr . Sesquiterpene emissions show little variation between different C. stoebe populations but vary substantially between different Centaurea species. Through root transcriptome sequencing, we identify six root-expressed sesquiterpene synthases (TPSs). Two root-specific TPSs, CsTPS4 and CsTPS5, are sufficient to produce the full blend of emitted root sesquiterpenes. VOC-exposure experiments demonstrate that C. stoebe root VOCs have neutral to positive effects on the germination and growth of different sympatric neighbours. Thus, constitutive root sesquiterpenes produced by two C. stoebe TPSs are associated with facilitation of sympatric neighbouring plants. The release of root VOCs may thus influence plant community structure in nature.
植物叶片排放的挥发性有机化合物（VOC）会影响邻近植物的生理机能。与叶片 VOC 相比，根系 VOC 在植物-植物相互作用中的作用知之甚少。在这里，我们描述了多枝鸦葱（Centaurea stoebe）组成型根系 VOC 的排放，并探讨了这些 VOC 对不同同域植物物种萌发和生长的影响。我们表明，C. stoebe 根系排放大量的倍半萜，（E）-β-石竹烯的释放速率估计超过 3μg g 干重 hr -1 。不同 C. stoebe 种群之间的倍半萜排放差异很小，但在不同的鸦葱属物种之间差异很大。通过根系转录组测序，我们鉴定了六个根系表达的倍半萜合酶（TPS）。两个根系特异性 TPS，CsTPS4 和 CsTPS5，足以产生所有排放的根系倍半萜。VOC 暴露实验表明，C. stoebe 根系 VOC 对不同同域邻居的萌发和生长具有中性到积极的影响。因此，由两个 C. stoebe TPS 产生的组成型根系倍半萜与促进同域邻近植物有关。根系 VOC 的释放可能会影响自然植物群落结构。
