Kwon Eun-Hae, Adhikari Arjun, Khan Abdul Latif, Do Eunsu, Methela Nusrat Jahan, Lee Chung-Yeol, Kang Sang-Mo, Ku Kang-Mo, Yun Byung-Wook, Lee In-Jung
Department of Applied Biosciences, Kyungpook National University, Daegu, Republic of Korea.
Department of Engineering Technology, Cullen College of Engineering, University of Houston, Texas, USA.
J Pineal Res. 2025 Apr;77(3):e70052. doi: 10.1111/jpi.70052.
Climate change, specifically high temperatures, can reduce soil moisture and cause hypersaline conditions, which creates an unsustainable agro-production system. Microbial symbionts associated with plants relinquish stressful conditions by producing stress-protecting substances. Melatonin is a signaling and stress-protecting molecule for plants, but is least known for microbial symbionts and their function in stress protection. Here, our study shows that the melatonin-synthesizing Bacillus velezensis EH151 (27.9 ng/mL at 96 h) significantly improved host plant (Glycine max L.) growth, biomass, photosynthesis, and reduced oxidative stress during heat and salinity stress conditions than the non-inculcated control. The EH151 symbiosis enhanced the macronutrient (P, Ca, and K) and reduced Na uptake in shoots during stress conditions. The microbial inoculation significantly expressed the high-affinity K transporter, MYB transcription factor, Salt Overly Sensitive 1, Na/H antiporter 2, and heat shock transcription factors in spatio-temporal orders during heat and salinity stress (H&S 1, 3, 10, and 14 h). We observed that microbial strain significantly increased the plant's endogenous abscisic acid (49.5% in H&S 10 h), jasmonic acid (71% in H&S 10 h), and melatonin biosynthesis (418% in H&S 14 h). Metabolome map of plant defense response showed that EH151 enhanced activation of amino acid metabolism pathways (e.g., glutamate (34%) L-aspartate (82%), glycine (18.5%), and serine (58%) under H&S 14 h compared to non-inoculation). Conversely, the free sugars and organic acids within the central carbon metabolism were significantly activated in non-inoculated combined heat and salinity stress compared to inoculated plants-suggesting lesser defense energy activated for stress tolerance. In conclusion, the current results show promising effects of the microbial abilities of melatonin that can regulate host growth and defense responses. Utilization of beneficial strains like B. velezensis EH151 could be the ideal strategy to improve stress tolerance and overcome the adverse impact of climate-induced abrupt changes.
气候变化，特别是高温，会降低土壤湿度并导致高盐环境，从而形成一个不可持续的农业生产系统。与植物相关的微生物共生体通过产生应激保护物质来缓解胁迫条件。褪黑素是一种植物信号传导和应激保护分子，但对于微生物共生体及其在应激保护中的功能却知之甚少。在此，我们的研究表明，合成褪黑素的贝莱斯芽孢杆菌EH151（96小时时为27.9纳克/毫升）在高温和盐胁迫条件下，比未接种的对照显著改善了宿主植物（大豆）的生长、生物量、光合作用，并降低了氧化应激。在胁迫条件下，EH151共生增强了地上部大量养分（磷、钙和钾）的吸收，并减少了钠的吸收。在高温和盐胁迫（H&S 1、3、10和14小时）期间，微生物接种显著按时空顺序表达了高亲和力钾转运体、MYB转录因子、盐过度敏感1、钠/氢逆向转运蛋白2和热激转录因子。我们观察到，微生物菌株显著增加了植物的内源脱落酸（H&S 10小时时增加49.5%）、茉莉酸（H&S 10小时时增加71%）和褪黑素生物合成（H&S 14小时时增加418%）。植物防御反应的代谢组图谱显示，与未接种相比，EH151在H&S 14小时时增强了氨基酸代谢途径的激活（例如，谷氨酸（34%）、L-天冬氨酸（82%）、甘氨酸（18.5%）和丝氨酸（58%））。相反，与接种植物相比，在未接种的高温和盐胁迫组合条件下，中心碳代谢中的游离糖和有机酸被显著激活，这表明为胁迫耐受性激活的防御能量较少。总之，目前的结果显示了褪黑素微生物能力在调节宿主生长和防御反应方面的良好效果。利用像贝莱斯芽孢杆菌EH151这样的有益菌株可能是提高胁迫耐受性和克服气候突变不利影响的理想策略。
