Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Tartu 51006, Estonia; Faculty of Science, Institute of Biology, University of Neuchâtel, 2000 Neuchâtel, Switzerland.
Department of Environmental and Biological Chemistry, Chungbuk National University, Chungbuk 28644, Republic of Korea; Department of Microbiology and Molecular Genetics, University of California, Davis, CA 95616, USA.
J Plant Physiol. 2019 Nov;242:153032. doi: 10.1016/j.jplph.2019.153032. Epub 2019 Aug 22.
Methyl jasmonate (MeJA) is widely used as a model chemical to study hypersensitive responses to biotic stress impacts in plants. Elevated levels of methyl jasmonate induce jasmonate-dependent defense responses, associated with a decline in primary metabolism and enhancement of secondary metabolism of plants. However, there is no information of how stress resistance of plants, and accordingly the sensitivity to exogenous MeJA can be decreased by endophytic plant growth promoting rhizobacteria (PGPR) harboring ACC (1-aminocyclopropane-1-carboxylate) deaminase. In this study, we estimated stress alleviating potential of endophytic PGPR against MeJA-induced plant perturbations through assessing photosynthetic traits and stress volatile emissions. We used mild (5 mM) to severe (20 mM) MeJA and endophytic plant growth promoting rhizobacteria Burkholderia vietnamiensis CBMB40 and studied how MeJA and B. vietnamiensis treatments influenced temporal changes in photosynthetic characteristics and stress volatile emissions. Separate application of MeJA markedly decreased photosynthetic characteristics and increased lipoxygenase pathway (LOX) volatiles, volatile isoprenoids, saturated aldehydes, lightweight oxygenated compounds (LOC), geranyl-geranyl diphosphate pathway (GGDP) volatiles, and benzenoids. However, MeJA-treated leaves inoculated by endophytic bacteria B. vietnamiensis had substantially increased photosynthetic characteristics and decreased emissions of LOX, volatile isoprenoids and other stress volatiles compared with non-inoculated MeJA treatments, especially at later stages of recovery. In addition, analysis of leaf terpenoid contents demonstrated that several mono- and sesquiterpenes were de novo synthesized upon MeJA and B. vietnamiensis applications. This study demonstrates that foliar application of endophytic bacteria B. vietnamiensis can potentially enhance resistance to biotic stresses and contribute to the maintenance of the integrity of plant metabolic activity.
茉莉酸甲酯（MeJA）被广泛用作研究植物对生物胁迫影响产生过敏反应的模型化学物质。高水平的茉莉酸甲酯诱导茉莉酸依赖性防御反应，与植物初级代谢物的下降和次级代谢物的增强相关。然而，目前尚不清楚植物的抗逆性，以及含有 ACC（1-氨基环丙烷-1-羧酸）脱氨酶的内生植物促生根际细菌（PGPR）如何降低植物对外源 MeJA 的敏感性。在这项研究中，我们通过评估光合作用特性和应激挥发性排放来估计内生 PGPR 对 MeJA 诱导的植物扰动的缓解潜力。我们使用了轻度（5mM）到重度（20mM）的 MeJA 和内生植物促生根际细菌 Burkholderia vietnamiensis CBMB40，并研究了 MeJA 和 B. vietnamiensis 处理如何影响光合作用特性和应激挥发性排放的时间变化。单独施用 MeJA 显著降低了光合作用特性，增加了脂氧合酶途径（LOX）挥发物、挥发异戊二烯、饱和醛、轻质含氧化合物（LOC）、香叶基香叶基二磷酸途径（GGDP）挥发物和苯类化合物。然而，与未接种 MeJA 处理相比，内生细菌 B. vietnamiensis 接种的 MeJA 处理叶片的光合作用特性显著增加，LOX、挥发异戊二烯和其他应激挥发物的排放减少，尤其是在恢复的后期阶段。此外，叶片萜类化合物含量分析表明，几种单萜和倍半萜在 MeJA 和 B. vietnamiensis 应用时被从头合成。本研究表明，内生细菌 B. vietnamiensis 的叶面施用可能增强对生物胁迫的抗性，并有助于维持植物代谢活动的完整性。
