Methyl jasmonate triggers broad molecular and metabolic responses in alfalfa

Applying methyl jasmonate to the cultivated alfalfa variety “Zhongtian No. 3” produced coordinated changes in leaf chemistry, physiological indicators, anatomy and gene expression, according to a multi-omics study in BMC Plant Biology . The researchers treated alfalfa with different methyl jasmonate concentrations and combined measurements of leaf morphology and physiology with metabolomic and transcriptomic analyses. Across the treatments, they identified 3,166 differentially abundant metabolites, including compounds from major biochemical classes, while finding transcriptional activation of several phenylpropanoid-related and hormone-associated genes.

The results show a broad experimental response to the treatment, but they do not establish improved field performance, enhanced stress resistance or better animal nutrition. Leaf appearance and internal structure varied with methyl jasmonate concentration. The investigators observed greater yellowing as the concentration increased, while the activities of peroxidase and phenylalanine ammonia-lyase rose significantly.

The contents of soluble sugars, starch, total phenols and flavonoids also increased significantly. Superoxide dismutase activity changed significantly only at the highest concentration tested. Oligomeric proanthocyanidin content increased slightly at the low concentration and decreased significantly at high concentrations, demonstrating that the measured biochemical response did not move in the same direction for every compound.

Leaf sectioning and staining showed that leaf, palisade-tissue and spongy-tissue thickness decreased significantly at 0.15 and 0.3 mmol/L methyl jasmonate. Metabolomic profiling identified 3,166 differentially abundant metabolites, primarily flavonoids, terpenoids, amino acids and amino-acid derivatives. Transcriptomic analysis showed transcriptional activation of seven phenylpropanoid-related genes: C4H, F3H, CYP93B16, CYP75B1, CYP81E1/E7, IFS and CYP81E9.

Their activation provides a molecular connection between methyl jasmonate treatment and the observed changes in phenolic, flavonoid and related secondary metabolism. Hormone-related genes—including GH3, JAZ, COI-1, CAM, GS2, AHA1/2, EBF1/2 and PR1—were also consistently induced. The researchers interpreted this pattern as evidence that the jasmonate signaling cascade was engaged.

The simultaneous changes in gene expression, enzyme activity and metabolite abundance therefore describe linked responses across several regulatory and biochemical levels, although the study alone does not prove that every measured change caused an increase in resistance or forage quality. The experiment offers a detailed account of how exogenous methyl jasmonate can alter alfalfa at the molecular and metabolic levels. It was limited to one cultivated variety, and the reported higher-concentration treatments included visible leaf yellowing and significantly thinner leaf, palisade and spongy tissues alongside increases in several biochemical indicators.

These findings do not amount to a controlled comparison of agricultural benefits, nor do they show that the responses persist across growing environments or genetic backgrounds. The authors propose that methyl jasmonate induction could provide a theoretical basis for strategies aimed at increasing functional metabolites, optimizing forage nutritive value and breeding more stress-resistant alfalfa. Those potential applications remain proposals rather than demonstrated outcomes of the experiment, and the molecular response in “Zhongtian No. 3” must not be treated as evidence of a universal effect across alfalfa cultivars or field conditions.

Subject of Research: Molecular, physiological and metabolic responses of alfalfa to methyl jasmonate

Article Title: Comprehensive transcriptome and metabolome analysis revealing the molecular and metabolic basis of methyl jasmonate response in alfalfa

Article References: Xu, L., Duan, H., Cui, G., Zhang, Q., Long, R., Zhu, X., Wu, F., Wang, Y., Li, Y., Shen, J., Hu, Y., Lu, Y., & Yang, H. (2026). Comprehensive transcriptome and metabolome analysis revealing the molecular and metabolic basis of methyl jasmonate response in alfalfa. BMC Plant Biology. https://doi.org/10.1186/s12870-026-09796-w

Image Credits: AI Generated

DOI: 10.1186/s12870-026-09796-w

Keywords: alfalfa, methyl jasmonate, plant signaling, metabolomics, transcriptomics, secondary metabolites, phenylpropanoids, leaf anatomy, forage crops, Comprehensive, transcriptome, metabolome