Mirjam Meischner, Stefanie Dumberger, Lars Erik Daber, Simon Haberstroh, Jürgen Kreuzwieser, Jörg-Peter Schnitzler, Christiane Werner
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引用次数: 0
Abstract
Plants emit diverse volatile organic compounds (VOCs) from their leaves and roots for protection against biotic and abiotic stress. An important signaling cascade activated by aboveground herbivory is the jasmonic acid (JA) pathway that stimulates the production of VOCs. So far it remains unclear if the activation of this pathway also leads to enhanced VOC emissions from conifer roots, and how the interplay of above- and belowground defenses in plants are affected by multiple stressors. Therefore, we simultaneously analyzed needle and root VOC emissions of Picea abies saplings, as well as CO2 and H2O fluxes in response to aboveground JA treatment, heat stress and their interaction in a controlled climate chamber experiment. Continuous online VOC measurements by PTR-TOF-MS showed an inverse pattern of total needle and root VOC emissions, when plants were treated with JA and heat. While needle sesquiterpene emissions increased nine-fold one day after JA application, total root VOC emissions decreased. This was mainly due to reduced emissions of acetone and monoterpenes by roots. In response to aboveground JA treatment, root total carbon emitted as VOCs decreased from 31% to only 4%. While VOC emissions aboveground increased, net CO2 assimilation strongly declined due to JA treatment, resulting in net respiration during the day. Interestingly, root respiration was not affected by aboveground JA application. Under heat the effect of JA on VOC emissions of needles and roots was less pronounced. The buffering effect of heat on VOC emissions following JA treatment points towards an impaired defense reaction of the plants under multiple stress. Our results indicate efficient resource allocation within the plant to protect threatened tissues by a rather local VOC release. Roots may only be affected indirectly by reduced belowground carbon allocation, but are not involved directly in the JA-induced stress response.
植物从叶片和根部释放出多种挥发性有机化合物(VOCs),以抵御生物和非生物胁迫。地上部食草动物激活的一个重要信号级联是刺激产生挥发性有机化合物的茉莉酸(JA)途径。到目前为止,人们还不清楚这一途径的激活是否也会导致针叶树根部挥发性有机化合物排放的增加,也不清楚植物的地上和地下防御系统是如何受到多种胁迫因素影响的。因此,我们在受控气候室实验中同时分析了黑松树苗针叶和根部的挥发性有机化合物排放,以及二氧化碳和水通量对地上部 JA 处理、热胁迫及其相互作用的响应。通过 PTR-TOF-MS 对挥发性有机化合物的连续在线测量显示,当植物受到 JA 和热处理时,针叶和根部挥发性有机化合物的总排放量呈反比模式。施用 JA 一天后,针叶倍半萜的排放量增加了九倍,而根部挥发性有机化合物的总排放量却减少了。这主要是由于根部丙酮和单萜的排放量减少。作为对地上部分 JA 处理的反应,根部以挥发性有机化合物形式排放的总碳量从 31% 降至仅 4%。在地上部挥发性有机化合物排放量增加的同时,二氧化碳净同化量却因 JA 处理而大幅下降,导致白天出现净呼吸。有趣的是,根的呼吸作用并没有受到地面施用 JA 的影响。在高温条件下,JA 对针叶和根的挥发性有机化合物排放的影响不太明显。JA 处理后热量对挥发性有机化合物排放的缓冲作用表明,植物在多重胁迫下的防御反应受损。我们的研究结果表明,植物内部的资源分配效率很高,可以通过局部释放挥发性有机化合物来保护受到威胁的组织。根系可能只受到地下碳分配减少的间接影响,但并不直接参与 JA 诱导的胁迫反应。
期刊介绍:
Tree Physiology promotes research in a framework of hierarchically organized systems, measuring insight by the ability to link adjacent layers: thus, investigated tree physiology phenomenon should seek mechanistic explanation in finer-scale phenomena as well as seek significance in larger scale phenomena (Passioura 1979). A phenomenon not linked downscale is merely descriptive; an observation not linked upscale, might be trivial. Physiologists often refer qualitatively to processes at finer or coarser scale than the scale of their observation, and studies formally directed at three, or even two adjacent scales are rare. To emphasize the importance of relating mechanisms to coarser scale function, Tree Physiology will highlight papers doing so particularly well as feature papers.