Karimian Asra, Bahramnejad Bahman, Siosemardeh Adell, Salehi Hemn, Ahmad Nariman Salih
Faculty of Agriculture, Department of Plant Production and Genetics, University of Kurdistan, Sanandaj, Iran.
College of Agricultural Engineering Sciences, Department of Biotechnology and Crop Science, University of Sulaimani, Kurdistan, Iraq.
BMC Plant Biol. 2025 Jul 1;25(1):789. doi: 10.1186/s12870-025-06830-1.
Drought stress significantly affects global crop yields, necessitating innovative strategies to enhance plant resilience. This study explored the role of the endophytic bacterium COBR7 in promoting melatonin biosynthesis and drought tolerance in two chickpea ( L.) cultivars, Samin (drought-tolerant) and ILC3279 (drought-sensitive). Melatonin biosynthesis genes in chickpeas were identified by comparing homologous sequences from closely related species in the NCBI database using the BLASTP method. Four (Tryptophan decarboxylase), two (Serotonin N-acetyltransferase), seven (Caffeic acid O-methyltransferase), and one (N-acetylserotonin O-methyltransferase) genes were identified in chickpeas. We examined their expression by real-time PCR under two conditions (inoculated and non-inoculated with bacteria) and three irrigation conditions (control, moderate drought, and severe drought). Inoculation with significantly enhanced the expression of , , and genes, particularly under severe drought stress, with the highest expression levels observed in the inoculated plants. Gas chromatography-mass spectrometry (GC-MS) analyses revealed that melatonin concentrations increased under drought conditions, with inoculated samples exhibiting higher levels than non-inoculated controls. In this study, drought stress- and treatment-induced changes were observed in other metabolites (amino acids, sugars, and organic acids) in both cultivars. OrthoVenn2-based comparative genomic analysis identified 544 conserved orthologous gene clusters shared between and , including stress-responsive genes (e.g., superoxide dismutase, ACC deaminase) and metabolic pathways critical for drought adaptation, such as tryptophan biosynthesis—a precursor for melatonin. These shared clusters suggest a synergistic interaction in which COBR7 primes melatonin-mediated drought tolerance in chickpea, potentially through the bacterial provision of tryptophan-derived intermediates or the modulation of plant stress signaling. This highlights COBR7’s role as a bioinoculant to enhance resilience in water-limited agroecosystems.
干旱胁迫显著影响全球作物产量，因此需要创新策略来增强植物的抗逆性。本研究探讨了内生细菌COBR7在促进两种鹰嘴豆（L.）品种Samin（耐旱）和ILC3279（干旱敏感）褪黑素生物合成和耐旱性方面的作用。通过使用BLASTP方法比较NCBI数据库中近缘物种的同源序列，鉴定了鹰嘴豆中的褪黑素生物合成基因。在鹰嘴豆中鉴定出四个（色氨酸脱羧酶）、两个（血清素N-乙酰转移酶）、七个（咖啡酸O-甲基转移酶）和一个（N-乙酰血清素O-甲基转移酶）基因。我们通过实时PCR在两种条件（接种细菌和未接种细菌）和三种灌溉条件（对照、中度干旱和重度干旱）下检测了它们的表达。接种COBR7显著增强了、和基因的表达，特别是在重度干旱胁迫下，接种植物中观察到最高表达水平。气相色谱-质谱（GC-MS）分析表明，干旱条件下褪黑素浓度增加，接种样品的水平高于未接种对照。在本研究中，在两个品种的其他代谢物（氨基酸、糖和有机酸）中观察到干旱胁迫和接种处理引起的变化。基于OrthoVenn2的比较基因组分析确定了COBR7和鹰嘴豆之间共有的544个保守直系同源基因簇，包括应激反应基因（如超氧化物歧化酶、ACC脱氨酶）和对干旱适应至关重要的代谢途径，如色氨酸生物合成——褪黑素的前体。这些共有的基因簇表明存在协同相互作用，其中COBR7可能通过提供色氨酸衍生的中间体或调节植物应激信号，引发鹰嘴豆中褪黑素介导的耐旱性。这突出了COBR7作为生物接种剂在增强水分受限农业生态系统抗逆性方面的作用。
