Plants as immovable organisms sense the stressors in their environment and respond to them by means of dedicated stress response pathways. In response to stress, jasmonates (jasmonic acid, its ...precursors and derivatives), a class of polyunsaturated fatty acid-derived phytohormones, play crucial roles in several biotic and abiotic stresses. As the major immunity hormone, jasmonates participate in numerous signal transduction pathways, including those of gene networks, regulatory proteins, signaling intermediates, and proteins, enzymes, and molecules that act to protect cells from the toxic effects of abiotic stresses. As cellular hubs for integrating informational cues from the environment, jasmonates play significant roles in alleviating salt stress, drought stress, heavy metal toxicity, micronutrient toxicity, freezing stress, ozone stress, CO
stress, and light stress. Besides these, jasmonates are involved in several developmental and physiological processes throughout the plant life. In this review, we discuss the biosynthesis and signal transduction pathways of the JAs and the roles of these molecules in the plant responses to abiotic stresses.
Damage-inducible defenses in plants are controlled in part by jasmonates, fatty acid-derived regulators that start to accumulate within 30 s of wounding a leaf.
Using liquid chromatography–tandem ...mass spectrometry, we sought to identify the 13-lipoxygenases (13-LOXs) that initiate wound-induced jasmonate synthesis within a 190-s timeframe in Arabidopsis thaliana in 19 single, double, triple and quadruple mutant combinations derived from the four 13-LOX genes in this plant.
All four 13-LOXs were found to contribute to jasmonate synthesis in wounded leaves: among them LOX6 showed a unique behavior. The relative contribution of LOX6 to jasmo-nate synthesis increased with distance from a leaf tip wound, and LOX6 was the only 13-LOX necessary for the initiation of early jasmonate synthesis in leaves distal to the wounded leaf.
Herbivory assays that compared Spodoptera littoralis feeding on the lox2-1 lox3B lox4A lox6A quadruple mutant and the lox2-1 lox3B lox4A triple mutant revealed a role for LOX6 in defense of the shoot apical meristem. Consistent with this, we found that LOX6 promoter activity was strong in the apical region of rosettes. The LOX6 promoter was active in and near developing xylem cells and in expression domains we term subtrichomal mounds.
Summary
The plant hormone jasmonic acid (JA) is involved in the cold stress response, and the inducer of CBF expression 1 (ICE1)‐ C‐repeat binding factor (CBF) regulatory cascade plays a key role in ...the regulation of cold stress tolerance. In this study, we showed that a novel B‐box (BBX) protein MdBBX37 positively regulates JA‐mediated cold‐stress resistance in apple.
We found that MdBBX37 bound to the MdCBF1 and MdCBF4 promoters to activate their transcription, and also interacted with MdICE1 to enhance the transcriptional activity of MdICE1 on MdCBF1, thus promoting its cold tolerance.
Two JA signaling repressors, MdJAZ1 and MdJAZ2 (JAZ, JAZMONATE ZIM‐DOMAIN), interacted with MdBBX37 to repress the transcriptional activity of MdBBX37 on MdCBF1 and MdCBF4, and also interfered with the interaction between MdBBX37 and MdICE1, thus negatively regulating JA‐mediated cold tolerance. E3 ligase MdMIEL1 (MIEL1, MYB30‐Interacting E3 Ligase1) reduced MdBBX37‐improved cold resistance by mediating ubiquitination and degradation of the MdBBX37 protein.
The data reveal that MIEL1 and JAZ proteins co‐regulate JA‐mediated cold stress tolerance through the BBX37‐ICE1‐CBF module in apple. These results will aid further examination of the post‐translational modification of BBX proteins and the regulatory mechanism of JA‐mediated cold stress tolerance.
• Background Jasmonates are important regulators in plant responses to biotic and abiotic stresses as well as in development. Synthesized from lipid-constituents, the initially formed jasmonic acid ...is converted to different metabolites including the conjugate with isoleucine. Important new components of jasmonate signalling including its receptor were identified, providing deeper insight into the role of jasmonate signalling pathways in stress responses and development. • Scope The present review is an update of the review on jasmonates published in this journal in 2007. New data of the last five years are described with emphasis on metabolites of jasmonates, on jasmonate perception and signalling, on cross-talk to other plant hormones and on jasmonate signalling in response to herbivores and pathogens, in symbiotic interactions, in flower development, in root growth and in light perception. • Conclusions The last few years have seen breakthroughs in the identification of JASMONATE ZIM DOMAIN (JAZ) proteins and their interactors such as transcription factors and co-repressors, and the crystallization of the jasmonate receptor as well as of the enzyme conjugating jasmonate to amino acids. Now, the complex nature of networks of jasmonate signalling in stress responses and development including hormone cross-talk can be addressed.
Plants produce a large variety of secondary metabolites including alkaloids, glucosinolates, terpenoids and phenylpropanoids. These compounds play key roles in plant-environment interactions and many ...of them have pharmacological activity in humans. Jasmonates (JAs) are plant hormones which induce biosynthesis of many secondary metabolites. JAs-responsive transcription factors (TFs) that regulate the JAs-induced accumulation of secondary metabolites belong to different families including AP2/ERF, bHLH, MYB and WRKY. Here, we give an overview of the types and functions of TFs that have been identified in JAs-induced secondary metabolite biosynthesis, and highlight their similarities and differences in regulating various biosynthetic pathways. We review major recent developments regarding JAs-responsive TFs mediating secondary metabolite biosynthesis, and provide suggestions for further studies.
SUMMARY
Jasmonate (JA) induces the biosynthesis of anthocyanin and proanthocyanidin. MdMYB9 is essential for modulating the accumulation of both anthocyanin and proanthocyanidin in apple, but the ...molecular mechanism for induction of anthocyanin and proanthocyanidin biosynthesis by JA is unclear. In this study, we discovered an apple telomere‐binding protein (MdTRB1) to be the interacting protein of MdMYB9. A series of biological assays showed that MdTRB1 acted as a positive modulator of anthocyanin and proanthocyanidin accumulation, and is dependent on MdMYB9. MdTRB1 interacted with MdMYB9 and enhanced the activation activity of MdMYB9 to its downstream genes. In addition, we found that the JA signaling repressor MdJAZ1 interacted with MdTRB1 and interfered with the interaction between MdTRB1 and MdMYB9, therefore negatively modulating MdTRB1‐promoted biosynthesis of anthocyanin and proanthocyanidin. These results show that the JAZ1–TRB1–MYB9 module dynamically modulates JA‐mediated accumulation of anthocyanin and proanthocyanidin. Taken together, our data further expand the functional study of TRB1 and provide insights for further studies of the modulation of anthocyanin and proanthocyanidin biosynthesis by JA.
Significance Statement
The apple telomere‐binding protein MdTRB1 positively modulates JA‐mediated accumulation of anthocyanin and proanthocyanidin by interacting with MdMYB9 and enhancing the activation activity of MdMYB9 to MdANS and MdANR. The JA signaling repressor MdJAZ1 interacted with MdTRB1 and interfered with the interaction between MdTRB1 and MdMYB9, therefore negatively modulating MdTRB1‐promoted biosynthesis of anthocyanin and proanthocyanidin.
TIFY proteins are plant-specific transcription factors, which play important role in multiple biological processes in plants. Here, seventeen TIFY genes in cucumber (Cucumis sativus L.) were ...identified and could be divided into ZML (4 genes), JAZ (10 genes), TIFY (2 genes), and PPD (1 gene) subfamilies. TIFY family has various protein lengths (80aa-324aa) and gene exon numbers (2-11). In this study, phylogenetic tree, Ka/Ks ratio, and collinearity analysis provide more clues for the origin and evolution of the cucumber TIFY family. The prediction of protein interaction and cis-acting element reveal the function of TIFY family genes. RNA-seq data showed that all the TIFY genes respond to powdery mildew and downy mildew. qRT-PCR analysis showed that the expression of JAZ subfamily genes was significantly changed when plants were infected by four common cucumber diseases (powdery mildew, downy mildew, gummy stem blight, and gray mold). In particular, CsJAZ1 and CsJAZ2 were regulated by four pathogens, indicating that these two genes might play important roles in plant immunity. In addition, the relative expression of CsJAZ8 was up-regulated, while the relative expression of CsJAZ9 was down-regulated in disease resistance response. This study provides further understanding for the cucumber TIFY family genes and reveals that JAZ genes play important roles in cucumber hormone transmission and plant defense.
Jasmonate ZIM-domain (JAZ) proteins, which act as negative regulators in the jasmonic acid (JA) signalling pathway, have significant implications for plant development and response to abiotic stress. ...Through a comprehensive genome-wide analysis, a total of 20 members of the JAZ gene family specific to alfalfa were identified in its genome. Phylogenetic analysis divided these 20 MsJAZ genes into five subgroups. Gene structure analysis, protein motif analysis, and 3D protein structure analysis revealed that alfalfa JAZ genes in the same evolutionary branch share similar exon-intron, motif, and 3D structure compositions. Eight segmental duplication events were identified among these 20 MsJAZ genes through collinearity analysis. Among the 32 chromosomes of the autotetraploid cultivated alfalfa, there were 20 MsJAZ genes distributed on 17 chromosomes. Extensive stress-related cis-acting elements were detected in the upstream sequences of MsJAZ genes, suggesting that their response to stress has an underlying function. Furthermore, the expression levels of MsJAZ genes were examined across various tissues and under the influence of salt stress conditions, revealing tissue-specific expression and regulation by salt stress. Through RT-qPCR experiments, it was discovered that the relative expression levels of these six MsJAZ genes increased under salt stress. In summary, our study represents the first comprehensive identification and analysis of the JAZ gene family in alfalfa. These results provide important information for exploring the mechanism of JAZ genes in alfalfa salt tolerance and identifying candidate genes for improving the salt tolerance of autotetraploid cultivated alfalfa via genetic engineering in the future.
•Overexpression of SlJAZ2 decreases the plant and internode length.•Tomato plants overexpressing SlJAZ2 exhibits reduced the trichomes in stem epidermis.•SlJAZ2 overexpression plants generates ...lateral buds earlier than wild-type.•SlJAZ2 accelerates the flower initiation in tomato plants.
JAZ (Jasmonate ZIM-domain) proteins are important repressors in JA signaling pathway. JAZs were proved taking part in various development processes and resistance to biotic and abiotic stresses in Arabiodopsis. However, in tomato, the functional study of JAZs is rare, especially on plant growth and development. Here, a typical tomato JAZ gene, SlJAZ2 was isolated. Tomato plants overexpressing SlJAZ2 exhibited quicker leaf initiation, reduced plant height and internode length, decreasing trichomes, earlier lateral bud emergence and advanced flowering transition. Further experiments showed that the pith cells in transgenic plant stem were much smaller than wild-type and the genes related to cell elongation and gibberellin biosynthesis were down-regulated. Genes mediating trichome formation were also inhibited in plant stem epidermis. In addition, the flower initiation of transgenic plants were earlier and genes controlling flowering time were up-regulated significantly after SlJAZ2 was overexpressed. Our research demonstrates that SlJAZ2 accelerates the transition from vegetative growth to reproductive growth.
Plant‐parasitic nematodes can cause devastating damage to crops. These nematodes secrete effectors that suppress the host immune responses to enhance their survival. In this study, Mj2G02, an ...effector from Meloidogyne javanica, is described. In situ hybridization and transcriptional analysis showed that Mj2G02 was highly expressed in the early infection stages and exclusively expressed in the nematode subventral oesophageal gland cells. In planta RNA interference targeting Mj2G02 impaired M. javanica parasitism, and Mj2G02‐transgenic Arabidopsis lines displayed more susceptibility to M. javanica. Using an Agrobacterium‐mediated transient expression system and plant immune response assays, we demonstrated that Mj2G02 localized in the plant cell nuclei and could suppress Gpa2/RBP‐1‐induced cell death. Moreover, by RNA‐Seq and quantitative reverse transcription PCR analyses, we showed that Mj2G02 was capable of interfering with the host jasmonic acid (JA) signalling pathway. Multiple jasmonate ZIM‐domain (JAZ) genes were significantly upregulated, whereas the JAR1 gene and four JA‐responsive genes, MYC3, UPI, THI2.1, and WRKY75, were significantly downregulated. In addition, HPLC analysis showed that the endogenous jasmonoyl‐isoleucine (JA‐Ile) level in Mj2G02‐transgenic Arabidopsis lines was significantly decreased compared to that in wildtype plants. Our results indicate that the M. javanica effector Mj2G02 suppresses the plant immune response, therefore facilitating nematode parasitism. This process is probably mediated by a JA‐Ile reduction and JAZ enhancement to repress JA‐responsive genes.
The effector Mj2G02 from Meloidogyne javanica reduces JA‐Ile and promotes JAZ proteins to repress JA‐responsive genes and impair the plant immunity.
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