Center Agriculture Food Environment (C3A), University of Trento, San Michele all'Adige, Trento, Italy.
Institute of Bioanalytics and Agro-Metabolomics, Department of Agrobiotechnology (IFA-Tulln), University of Natural Resources and Life Sciences, Tulln, Austria.
Physiol Plant. 2024 May-Jun;176(3):e14352. doi: 10.1111/ppl.14352.
Climate change is responsible for mild winters and warm springs that can induce premature plant development, increasing the risk of exposure to cold stress with a severe reduction in plant growth. Tomato plants are sensitive to cold stress and beneficial microorganisms can increase their tolerance. However, scarce information is available on mechanisms stimulated by bacterial endophytes in tomato plants against cold stress. This study aimed to clarify metabolic changes stimulated by psychrotolerant endophytic bacteria in tomato plants exposed to cold stress and annotate compounds possibly associated with cold stress mitigation. Tomato seeds were inoculated with two bacterial endophytes isolated from Antarctic Colobanthus quitensis plants (Ewingella sp. S1.OA.A_B6 and Pseudomonas sp. S2.OTC.A_B10) or with Paraburkholderia phytofirmans PsJN, while mock-inoculated seeds were used as control. The metabolic composition of tomato plants was analyzed immediately after cold stress exposure (4°C for seven days) or after two and four days of recovery at 25°C. Under cold stress, the content of malondialdehyde, phenylalanine, ferulic acid, and p-coumaric acid was lower in bacterium-inoculated compared to mock-inoculated plants, indicating a reduction of lipid peroxidation and the stimulation of phenolic compound metabolism. The content of two phenolic compounds, five putative phenylalanine-derived dipeptides, and three further phenylalanine-derived compounds was higher in bacterium-inoculated compared to mock-inoculated samples under cold stress. Thus, psychrotolerant endophytic bacteria can reprogram polyphenol metabolism and stimulate the accumulation of secondary metabolites, like 4-hydroxybenzoic and salicylic acid, which are presumably involved in cold stress mitigation, and phenylalanine-derived dipeptides possibly involved in plant stress responses.
气候变化导致冬季温和、春季温暖，这可能促使植物提前发育，增加了植物暴露在冷胁迫下的风险，导致植物生长严重减少。番茄植物对冷胁迫敏感，有益微生物可以提高其耐受性。然而，关于细菌内生菌在番茄植物中对冷胁迫的刺激机制的信息很少。本研究旨在阐明在冷胁迫下受耐冷内生细菌刺激的番茄植物的代谢变化，并注释可能与缓解冷胁迫相关的化合物。将两种从南极 Colobanthus quitensis 植物中分离的内生细菌（Ewingella sp. S1.OA.A_B6 和 Pseudomonas sp. S2.OTC.A_B10）或 Paraburkholderia phytofirmans PsJN 接种到番茄种子中，而模拟接种的种子作为对照。在冷胁迫暴露后（4°C 持续七天）或在 25°C 下恢复两天和四天后，立即分析番茄植物的代谢组成。在冷胁迫下，与模拟接种的植物相比，接种细菌的植物中丙二醛、苯丙氨酸、阿魏酸和对香豆酸的含量较低，表明脂质过氧化的减少和酚类化合物代谢的刺激。在冷胁迫下，与模拟接种的样品相比，接种细菌的样品中两种酚类化合物、五种假定的苯丙氨酸衍生二肽和三种进一步的苯丙氨酸衍生化合物的含量更高。因此，耐冷内生细菌可以重新编程多酚代谢并刺激次生代谢物的积累，如 4-羟基苯甲酸和水杨酸，这些物质可能参与冷胁迫缓解，而苯丙氨酸衍生的二肽可能参与植物应激反应。
