Jasmonoyl-l-isoleucine hydrolase 1 (JIH1) contributes to a termination of jasmonate signaling inN. attenuata

Abstract

In the world of complex ecological interactions, optimal performance requires maintenance of homeostasis. For instance, in response to herbivore attack, plants reconfigure their metabolism and produce potent defensive secondary metabolites 1-3 ; a process mediated by the highly conserved jasmonate signaling pathway. [4][5][6][7] The jasmonate signaling cascade is induced in response to herbivore attack and leads to the rapid accumulation of jasmonic acid (JA) and its bioactive form -jasmonoyl-LIle (JA-Ile) -which, through a series of molecular interactions, results in the transcriptomic and metabolic reconfigurations and plant defense responses. [8][9][10][11] However, due to the potential metabolic cost of jasmonate-induced defenses, 12-14 plants tightly regulate the biosynthesis and catabolism of jasmonates.Generally, plants maintain the homeostasis of active hormone by either conjugating them with small molecules such as sugars or amino acids, or inactivating them through a series of chemical modifications. [15][16][17] Recently, two Arabidopsis thaliana cytochrome p450 enzymes (CYP94B3 and CYP94C1) were demonstrated to attenuate jasmonate responses by catabolizing JA-Ile to its inactive forms, 12-OH-JA-Ile and 12-COOH-JAIle. A. thaliana plants that ectopically expressed CYP94B3 were male sterile and insensitive to jasmonate-mediated root growth inhibition (and chlorosis); phenotypes reminiscent of jasmonate deficiency. Conversely, a significant increase was observed in the accumulation of JA-Ile when knockout cyp94b3 and cyp94c1 A. thaliana plants were wounded, confirming the negative role of these enzymes in the regulation of the herbivore-induced jasmonate burst. However, at later time points, the level of the wound-induced JA-Ile in Atcyp94b3 plants waned to the basal level, indicating the existence of alternative mechanisms to attenuate the JA-Ile burst. [18][19][20] In our group, we identified a novel hydrolase in Nicotiana attenuata and demonstrated its hydrolytic function on jasmonoyl-l-isoleucine in vitro and in vivo (hence named as NaJIH1).21 After simulated herbivory, silenced N. attenuata plants (irJIH1) accumulated significantly more JA-Ile, and consequently, significantly more defense metabolites (nicotine, 17-hydroxygeranyllinalool diterpene glycosides and proteinase inhibitors) than did wild type (WT) plants. The increased accumulation of defense metabolites correlated with the reduced performance of the specialist (Manduca sexta) and the generalist (Spodoptera littoralis) herbivores reared on irJIH1 plants. In the field (Great Basin Desert, Utah, USA), we attached Manduca sexta eggs to the underside leaves of WT and irJIH1 plants and compared the percentage of eggs predated upon by egg predators (Geocoris spp.). We found that irJIH1 plants experienced Keywords: Jasmonate signaling pathway, JA-Ile hydrolase 1, jasmonate burst, jasmonic acid, jasmonoyl-L-jsoleucine, herbivore defense the jasmonate signaling pathway is essential for plant development, reproduction, and defense against herbivores...

Metabolomic Characterisation of Discriminatory Metabolites Involved in Halo Blight Disease in Oat Cultivars Caused by Pseudomonas syringae pv. coronafaciens

“…“Dunnart” could have therefore, had a lower abundance due to an earlier mobilisation of the pathogen-triggered signals and subsequent conversion and deactivation of the bioactive jasmonoyl-isoleucine into a non-active conjugate when it was no longer needed. These signalling hormones cause transcriptomic and metabolic reconfigurations that aid in plant defence responses [ 61 , 62 ]. Many different jasmonate precursors and derivatives have been known to exhibit biological activity, including jasmonic-amino acid conjugates [ 63 ], of which two were identified in this study in response to Ps-c infection.…”

Maize resistance to insect herbivory is enhanced by silencing expression of genes for jasmonate‐isoleucine degradation using sugarcane mosaic virus

“…The level of plant defense induction is regulated by both the biosynthesis and degradation of JA-Ile (Figure 1). Whereas the JAR1 protein conjugates jasmonate and isoleucine to form JA-Ile (Koo & Howe, 2009;Staswick et al, 2002), experiments with Nicotiana attenuata showed that JA-Ile can be inactivated by JIH1-mediated cleavage to jasmonate and isoleucine (Woldemariam et al, 2012(Woldemariam et al, , 2014. Similarly, Arabidopsis thaliana (Arabidopsis) iar3 ill6 double knockouts, which are defective in JA-Ile deconjugation, exhibited increased JA-Ile accumulation (Marquis et al, 2020).…”

Use of sugarcane mosaic virus for virus-induced gene silencing in maize

“…The level of plant defense induction is regulated by both the biosynthesis and degradation of JA-Ile (Figure 1). Whereas the JAR1 protein conjugates jasmonate and isoleucine to form JA-Ile (Staswick et al, 2002; Koo and Howe, 2009), experiments with Nicotiana attenuata showed that JA-Ile can be inactivated by JIH1-mediated cleavage to jasmonate and isoleucine (Woldemariam et al, 2012; Woldemariam et al, 2014). Similarly, Arabidopsis thaliana (Arabidopsis) iar3 ill6 double knockouts, which are defective in JA-Ile deconjugation, exhibited increased JA-Ile accumulation (Marquis et al, 2020).…”