Jul 2026· Current opinion in plant biology· Vol 92, pp.
102926
· 0 citations· 73 references
Medicine
TL;DR
This review summarizes the current understanding of JA-Ile biosynthesis initiation, primarily in Arabidopsis, and highlights both recent advances and remaining challenges, with implications from long-distance signaling and emphasis on local wound responses.
Abstract
The lipid-derived phytohormone JA-Ile is a critical regulator of environmental and developmental responses in flowering plants. This signaling molecule protects plants against biotic and abiotic challenges and plays essential roles in reproductive development. JA-Ile production starts with polyunsaturated fatty acids esterified in plastidial membranes that are converted to OPDA, which is then transported to peroxisomes for JA formation, and finally conjugated to Ile in the cytosol to produce the bioactive hormone. While the genetic components involved in JA-Ile biosynthesis, perception and signaling have been uncovered, intracellular signaling events activating JA-Ile production and molecular mechanisms regulating biosynthetic enzyme functions have remained elusive. This review summarizes the current understanding of JA-Ile biosynthesis initiation, primarily in Arabidopsis, and highlights both recent advances and remaining challenges, with implications from long-distance signaling and emphasis on local wound responses.
This review synthesizes the significant advancements made over the past decade in understanding JA's role in regulating plant development and mediating responses to environmental stresses, areas that lacked systematic review in previous years.
Rui Wang, Teja Manda, A. Movahedi et al.· Functional Plant Biology· 0 citations
The plant hormone jasmonoyl-isoleucine (JA-Ile) reallocates resources from growth towards induced defenses upon microbial or herbivore attacks or other environmental threats. JA-Ile and its precursor jasmonic acid (JA) undergo complex enzymatic turnover that shape hormonal dynamics for optimal signaling. JA-Ile is inactivated through gradual oxidation by CYP94 monooxygenases, followed by 12-OH-JA-Ile deconjugation towards 12-OH-JA. 12-OH-JA was believed to originate also from direct JA hydroxylation by JAO/JOX dioxygenases. Here we investigate the nature and origins of hydroxy-JAs and their derivatives upon stress responses in Arabidopsis. Using a set of analytical methods to explore enzyme assays and multiple pathway-impaired mutants, we show that JAO enzymes produce exclusively 11-OH-JA rather than 12-OH-JA and define a separate branch in JA catabolism. Upon leaf wounding, the CYP94/AH and, to a lesser extent, the JAO pathways direct the respective accumulation of 12- and 11-OH-JAs and their 11/12-glucosylated and 12-sulfated derivatives with isoform-specific occurrences. In contrast,
Botrytis
infection triggers the exclusive accumulation of 11-OH-JA and 11-Glc-
O
-JA with complex patterns of HSO
4
-JA. Finally, treatment of
jar1
seedlings with 11-OH-JA does not trigger transcriptional changes, reinforcing the notion that the JAO/11-OH-JA pathway represents a metabolic sink modulating JA-Ile formation. Our findings elucidate the 11-OH-JA biosynthetic pathway and highlight stress-specific hydroxylation signatures.
T. Heitz, Valentin Marquis, Julie Zumsteg et al.· Nature Communications· 0 citations
The jasmonate (JA) phytohormone signaling pathway is a key regulator of plant resistance to insect herbivores by mediating the biosynthesis of anti-herbivore metabolites and proteins. However, the JA-mediated regulatory network and its downstream defensive compounds in the monocot crop rice remain largely unknown. Here, we investigate the role of the MYB transcription factor MYB55 in JA-mediated rice defense against insect herbivores. Knockout of MYB55 enhances feeding by both brown planthopper (BPH) and leaf folder (LF), while having no effect on BPH oviposition. MYB55 directly binds to AC motifs in the promoters of initial phenylpropanoid pathway genes, including phenylalanine ammonia-lyase, cinnamate 4-hydroxylase, and 4-coumaroyl:CoA ligase, as well as downstream lignin biosynthetic genes, and activates their transcription. In addition to lignin, accumulation of BPH- and LF-induced phenolic acid-amine conjugates (phenolamides) is significantly reduced in myb55 mutants compared with wild-type plants. The expression of MYB55 is induced by herbivory and regulated by JA signaling. Mechanistically, the core JA regulator MYC2 directly binds to the MYB55 promoter, forming a MYC2-MYB55 transcriptional cascade. Collectively, this study reveals that JA-responsive MYB55 enhances rice defense against BPH and LF by reprogramming phenylpropanoid metabolism toward lignin and phenolamide biosynthesis.
Ya-Ze Kong, Zhi-Xin Wu, Meng-Yu Liu et al.· Plant, Cell and Environment· 0 citations
Findings suggest that VvJAZ2 may function as a potential regulatory node, and support a working model of a dynamic "transcription-protein interaction" module to coordinate hormone signaling and metabolic reprogramming under cold stress.
Miao Shao, Lili Che, Shixiong Lu et al.· International Journal of Bio...· 0 citations
The current understanding of SL biosynthesis and transport in Arabidopsis thaliana and Oryza sativa is summarized and the physiological functions of different SL species as plant hormones and rhizosphere signaling molecules are discussed, which largely remain unresolved.
Kiyoshi Mashiguchi, Shinjiro Yamaguchi· Journal of Experimental Bota...· 0 citations
SUMMARY Due to their sessile nature, plants are constantly exposed to the environment and must cope with sometimes extreme changes in conditions during the day or growing season. Plants depend on photosynthesis as their primary means to generate energy and building blocks, and adverse environmental conditions can stress the photosynthetic apparatus leading to the production of toxic byproducts. In the long term, stress experienced by the chloroplast must be communicated to the nucleus to adjust the expression of genes providing robust abiotic stress resilience in a process called retrograde signaling. Here, we propose a retrograde signaling mechanism that starts with the accumulation of phosphatidic acid at the outer chloroplast membrane. A mutant of Arabidopsis thaliana, lppγ lppɛ1, disrupted in two chloroplast envelope membrane‐located phosphatidic acid phosphatases, shows reduced growth and activation of abscisic acid‐mediated abiotic stress‐response pathways, among other changes, as determined by RNA‐Seq analysis. The mutant is more resistant to freezing and osmotic stress. To identify components of the proposed retrograde signaling pathway, we conducted a suppressor screen in the lppγ lppɛ1 mutant and identified a mutation that causes the loss of MED16, which is a component of Mediator, a transcriptional complex in the nucleus affecting the expression of genes involved in abiotic stress tolerance, among others. Based on these findings, we are proposing a lipid‐based, retrograde signaling mechanism in response to abiotic stresses such as freezing.
C. Hiser, Ron Cook, Yosia Mugume et al.· The Plant Journal· 0 citations
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