Dataset Information

Induction of Jasmonoyl-Isoleucine (JA-Ile)-Dependent JASMONATE ZIM-DOMAIN (JAZ) Genes in NaCl-Treated Arabidopsis thaliana Roots Can Occur at Very Low JA-Ile Levels and in the Absence of the JA/JA-Ile Transporter JAT1/AtABCG16.

ABSTRACT: The plant hormone jasmonoyl-isoleucine (JA-Ile) is an important regulator of plant growth and defense in response to various biotic and abiotic stress cues. Under our experimental conditions, JA-Ile levels increased approximately seven-fold in NaCl-treated Arabidopsis thaliana roots. Although these levels were around 1000-fold lower than in wounded leaves, genes of the JA-Ile signaling pathway were induced by a factor of 100 or more. Induction was severely compromised in plants lacking the JA-Ile receptor CORONATINE INSENSITIVE 1 or enzymes required for JA-Ile biosynthesis. To explain efficient gene expression at very low JA-Ile levels, we hypothesized that salt-induced expression of the JA/JA-Ile transporter JAT1/AtABCG16 would lead to increased nuclear levels of JA-Ile. However, mutant plants with different jat1 alleles were similar to wild-type ones with respect to salt-induced gene expression. The mechanism that allows COI1-dependent gene expression at very low JA-Ile levels remains to be elucidated.

SUBMITTER: Thurow C

PROVIDER: S-EPMC7760663 | biostudies-literature | 2020 Nov

REPOSITORIES: biostudies-literature

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Induction of Jasmonoyl-Isoleucine (JA-Ile)-Dependent JASMONATE ZIM-DOMAIN (JAZ) Genes in NaCl-Treated Arabidopsis thaliana Roots Can Occur at Very Low JA-Ile Levels and in the Absence of the JA/JA-Ile Transporter JAT1/AtABCG16.

Thurow Corinna C Krischke Markus M Mueller Martin J MJ Gatz Christiane C

Plants (Basel, Switzerland) 20201124 12

The plant hormone jasmonoyl-isoleucine (JA-Ile) is an important regulator of plant growth and defense in response to various biotic and abiotic stress cues. Under our experimental conditions, JA-Ile levels increased approximately seven-fold in NaCl-treated Arabidopsis thaliana roots. Although these levels were around 1000-fold lower than in wounded leaves, genes of the JA-Ile signaling pathway were induced by a factor of 100 or more. Induction was severely compromised in plants lacking th ...[more]

PMID: 33255380

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Project description:BackgroundJasmonate (JA) signaling and functions have been established in rice development and response to a range of biotic or abiotic stress conditions. However, information on the molecular actors and mechanisms underlying turnover of the bioactive jasmonoyl-isoleucine (JA-Ile) is very limited in this plant species.ResultsHere we explored two gene families in rice in which some members were described previously in Arabidopsis to encode enzymes metabolizing JA-Ile hormone, namely cytochrome P450 of the CYP94 subfamily (CYP94, 20 members) and amidohydrolases (AH, 9 members). The CYP94D subclade, of unknown function, was most represented in the rice genome with about 10 genes. We used phylogeny and gene expression analysis to narrow the study to candidate members that could mediate JA-Ile catabolism upon leaf wounding used as mimic of insect chewing or seedling exposure to salt, two stresses triggering jasmonate metabolism and signaling. Both treatments induced specific transcriptional changes, along with accumulation of JA-Ile and a complex array of oxidized jasmonate catabolites, with some of these responses being abolished in the JASMONATE RESISTANT 1 (jar1) mutant. However, upon response to salt, a lower dependence on JAR1 was evidenced. Dynamics of CYP94B5, CYP94C2, CYP94C4 and AH7 transcripts matched best the accumulation of JA-Ile catabolites. To gain direct insight into JA-Ile metabolizing activities, recombinant expression of some selected genes was undertaken in yeast and bacteria. CYP94B5 was demonstrated to catalyze C12-hydroxylation of JA-Ile, whereas similarly to its Arabidopsis bi-functional homolog IAR3, AH8 performed cleavage of JA-Ile and auxin-alanine conjugates.ConclusionsOur data shed light on two rice gene families encoding enzymes related to hormone homeostasis. Expression data along with JA profiling and functional analysis identifies likely actors of JA-Ile catabolism in rice seedlings. This knowledge will now enable to better understand the metabolic fate of JA-Ile and engineer optimized JA signaling under stress conditions.

Project description:The jasmonate hormones are essential regulators of plant defense against herbivores and include several dozen derivatives of the oxylipin jasmonic acid (JA). Among these, the conjugate jasmonoyl isoleucine (JA-Ile) has been shown to interact directly with the jasmonate co-receptor complex to regulate responses to jasmonate signaling. However, functional studies indicate that some aspects of jasmonate-mediated defense are not regulated by JA-Ile. Thus, it is not clear whether JA-Ile is best characterized as the master jasmonate regulator of defense, or if it regulates more specific aspects. We investigated possible functions of JA-Ile in anti-herbivore resistance of the wild tobacco Nicotiana attenuata, a model system for plant-herbivore interactions. We first analyzed the soluble and volatile secondary metabolomes of irJAR4xirJAR6, asLOX3, and WT plants, as well as an RNAi line targeting the jasmonate co-receptor CORONATINE INSENSITIVE 1 (irCOI1), following a standardized herbivory treatment. irJAR4xirJAR6 were the most similar to WT plants, having a ca. 60% overlap in differentially regulated metabolites with either asLOX3 or irCOI1. In contrast, while at least 25 volatiles differed between irCOI1 or asLOX3 and WT plants, there were few or no differences in herbivore-induced volatile emission between irJAR4xirJAR6 and WT plants, in glasshouse- or field-collected samples. We then measured the susceptibility of jasmonate-deficient vs. JA-Ile-deficient plants in nature, in comparison to wild-type (WT) controls, and found that JA-Ile-deficient plants (irJAR4xirJAR6) are much better defended even than a mildly jasmonate-deficient line (asLOX3). The differences among lines could be attributed to differences in damage from specific herbivores, which appeared to prefer either one or the other jasmonate-deficient phenotype. We further investigated the elicitation of one herbivore-induced volatile known to be jasmonate-regulated and to mediate resistance to herbivores: (E)-α-bergamotene. We found that JA was a more potent elicitor of (E)-α-bergamotene emission than was JA-Ile, and when treated with JA, irJAR4xirJAR6 plants emitted 20- to 40-fold as much (E)-α-bergamotene than WT. We conclude that JA-Ile regulates specific aspects of herbivore resistance in N. attenuata. This specificity may allow plants flexibility in their responses to herbivores and in managing trade-offs between resistance, vs. growth and reproduction, over the course of ontogeny.

Project description:BackgroundSugarcane smut caused by Sporisorium scitamineum is one of the most severe fungal diseases in the sugarcane industry. Using a molecular biological technique to mine sugarcane resistance genes can provide gene resources for further genetic engineering of sugarcane disease-resistant breeding. Jasmonate ZIM (zinc-finger inflorescence meristem) domain (JAZ) proteins, which involved in the responses to plant pathogens and abiotic stresses, are important signaling molecules of the jasmonic acid (JA) pathway.ResultsSeven differentially expressed sugarcane JAZ genes, ScJAZ1-ScJAZ7, were mined from the transcriptome of sugarcane after inoculation with S. scitamineum. Bioinformatic analyses revealed that these seven ScJAZ genes encoded basic proteins that contain the TIFY and CCT_2 domains. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis demonstrated that the ScJAZ1-ScJAZ7 genes were tissue specific and differentially expressed under adverse stress. During S. scitamineum infection, the transcripts of ScJAZ4 and ScJAZ5 were both upregulated in the susceptible genotype ROC22 and the resistant genotype Yacheng05-179; ScJAZ1, ScJAZ2, ScJAZ3, and ScJAZ7 were downregulated in Yacheng05-179 and upregulated in ROC22; and the expression of ScJAZ6 did not change in ROC22, but was upregulated in Yacheng05-179. The transcripts of the seven ScJAZ genes were increased by the stimuli of salicylic acid and abscisic acid, particularly methyl jasmonate. The expression of the genes ScJAZ1-ScJAZ7 was immediately upregulated by the stressors hydrogen peroxide, sodium chloride, and copper chloride, whereas slightly induced after treatment with calcium chloride and polyethylene glycol. In addition, the expression of ScJAZ6, as well as seven tobacco immunity-associated marker genes were upregulated, and antimicrobial activity against Pseudomonas solanacearum and Fusarium solani var. coeruleum was observed during the transient overexpression of ScJAZ6 in Nicotiana benthamiana, suggesting that the ScJAZ6 gene is associated with plant immunity.ConclusionsThe different expression profiles of the ScJAZ1-ScJAZ7 genes during S. scitamineum infection, the positive response of ScJAZ1-ScJAZ7 to hormones and abiotic treatments, and the function analysis of the ScJAZ6 gene revealed their involvement in the defense against biotic and abiotic stresses. The findings of the present study facilitate further research on the ScJAZ gene family especially their regulatory mechanism in sugarcane.

Dataset Information

Induction of Jasmonoyl-Isoleucine (JA-Ile)-Dependent JASMONATE ZIM-DOMAIN (JAZ) Genes in NaCl-Treated Arabidopsis thaliana Roots Can Occur at Very Low JA-Ile Levels and in the Absence of the JA/JA-Ile Transporter JAT1/AtABCG16.

Publications

Induction of Jasmonoyl-Isoleucine (JA-Ile)-Dependent <i>JASMONATE ZIM-DOMAIN</i> <i>(JAZ)</i> Genes in NaCl-Treated <i>Arabidopsis thaliana</i> Roots Can Occur at Very Low JA-Ile Levels and in the Absence of the JA/JA-Ile Transporter JAT1/AtABCG16.

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