Possible melatonin-induced salt stress tolerance pathway in Phaseolus vulgaris L. using transcriptomic and metabolomic analyses

Abstract

Melatonin plays important roles in multiple stress responses; however, the downstream signaling pathway and molecular mechanism remain unclear. This study aimed to elucidate the transcriptional regulation of melatonin-induced salt stress tolerance in Phaseolus vulgaris L. and identify the key downstream transcription factors of melatonin through transcriptomic and metabolomic analyses. The melatonin-induced transcriptional network of hormones, transcription factors, and functional genes was established under both control and stress conditions. Among these, eight candidate transcription factors were identified via gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, one gene related to transmembrane transport of salts (Phvul.004G177300). These genes may play a role in maintaining the cell structure and excreting sodium ions outside the cell or transporting them to the vacuoles for storage. Melatonin regulates the Phvul.009G210332 gene and metabolites C05642 (N-acetyl-N-2-formyl-5-methoxycanurine), C05643 (6-hydroxymelatonin), C05660 (5-methoxyindoleacetic acid) involved in tryptophan metabolism. The metabolites C05642 and C05643 were identified as decomposition products of tryptophan, indicating that exogenous melatonin entered the P. vulgaris tissue and was metabolized. Melatonin promotes the synthesis and metabolism of tryptophan, which is crucial to plant metabolism, growth, maintenance, and repair.

Creating Climate-Resilient Crops by Increasing Drought, Heat, and Salt Tolerance

“…As a metabolite synthesized from tryptophan, melatonin acts as an antioxidant in ROS defense, regulates cross talk between other phytohormones and ROS, and mediates many developmental processes including germination, circadian rhythm, fruit ripening, and in abiotic stress tolerance. In a recent study, the transcriptomic analysis of common bean plants treated with 100 µM melatonin showed an increased synthesis and metabolism of tryptophan that is involved in flavonoid metabolism, and alleviated the salt stress by affecting the cell wall-related gene expression [176]. Similarly, the antioxidant property of melatonin in conferring salt tolerance was reported in many plants such as fenugreek [177], eggplant [178], wheat [179], mustard [180], maize [181], legumes [182], and drought stress in quinoa [183], and basil [184].…”