Der JAZZ von Jasmonaten: Untersuchungen zum JA-Signalweg unter Verwendung von rationell-generierten Jasmonaten
Organismische Interaktionen, chemische Ökologie und Mikrobiome pflanzlicher Systeme
Zusammenfassung der Projektergebnisse
SUMMARY The aim of this project was to employ pharmacochemical, molecular and computational tools to explore the molecular bases of plant responses elicited by the rationally designed jasmonates “JA-Ile-lactones”. These molecules served as valuable tools to better understand the jasmonate (JA) signaling pathway, and therefore, to gain further insights on how plants maintain their ability to grow while protecting themselves against pathogen and herbivore attack. It was hypothesized that the capability of JA-Ilelactones to promote degradation of specific Jasmonate-ZIM-Domain (JAZ) proteins could control singular aspects of plant responses downstream to JA-Ile-lactone perception by the COI1-JAZ receptor complexes. Surprisingly, it was revealed that JA-Ile-lactones can be metabolized in vivo to generate the endogenous jasmonate 12-OH-JA-Ile, and therefore, they act as a slow-release system for natural molecule (unpublished data, see work report). Until this point, 12-OH-JA-Ile (a catabolite of the canonical COI1 ligand, JA-Ile) was considered an inactive jasmonate. Within this project it has been demonstrated that the naturally occurring 12-OH-JA-Ile is, contrary to its until then assumed inactivity, indeed a bioactive molecule that signals through binding to the canonical jasmonate co-receptors COI1- JAZs (Jimenez-Aleman et al., 2019). As a general trend, 12-OH-JA-Ile was a milder activator of JA- dependent responses than JA-Ile, although similar glucosinolate levels were induced by both ligands in Arabidopsis thaliana. JA-Ile ω-hydroxylation was proposed as an additional step in JA signaling that, in analogy to other plant hormone pathways (e.g. ABA and GA), fine-tunes JA dependent responses consequently improving plants adaptive capacity and resilience. Motivated by the surprising results generated with JA-Ile-lactones and 12-OH-JA-Ile, the effect of these compounds on jasmonate signaling was further explored in different plant species, including the crop plants tomato and rice. Importantly, in a close collaboration with the lab of Prof. Minoru Ueda, Tohoku University, Japan, it has been established that JA-Ile-lactones are converted into 12-OH-JA-Ile also in Solanaceae species such as tomato, and selectively activate the plant immune system in a longlasting COI1-dependent manner. Conclusions on this study have been delayed due to the Covid-19 pandemic and the results will be published in due course (unpublished data, see work report below). In another fruitful collaboration, this time with the lab of Dr. Ran Li, Zhejiang University, China, it was found that, in addition to JA-Ile, other two JA-amino acid conjugates, namely JA-Val and JA-Leu are involved in plant defense against three different herbivore insects in rice. These compounds directly bind to the JA co-receptor complex in rice, OsCOI1-OsJAZ, and promote the degradation of OsJAZs, therefore triggering the production of herbivore-elicited defensive compounds (Fu et al., 2022). Finally, taking advantage of the excellent synergy between the skills existing in the host lab (molecular biology and biochemistry) and my own skills (chemistry and ecology), the jasmonate signaling in the emerging model plant Marchantia polymorpha was explored. Two main subjects were studied in this system, the production of jasmonate regulated metabolites with anti-SARS-CoV-2 activity, and the capability of long chain polyunsaturated fatty acids (LCPUFAs) as the precursors of bioactive jasmonates in M. polymorpha. First, in collaboration with the “Antiviral Discovery Platform”, at the host institution, I was able to exploit the potential of plant metabolism to identified a potent SARS-CoV-2 antiviral. Following a bioactivity-guided fractionation and mass-spectrometry (MS) approach, we found that the chlorophyll derivative Pheophorbide a (PheoA), a porphyrin compound similar to animal Protoporphyrin IX, has an extraordinary anti SARS-CoV-2 activity. PheoA prevents the infection of cultured monkey and human cells without noticeable cytotoxicity. The chlorophyll derivative targets the viral particle interfering with its infectivity in a dose- and time-dependent manner. Besides SARS-CoV-2, PheoA also displayed a broad-spectrum antiviral activity against enveloped RNA viral pathogens such as HCV, West Nile, and other coronaviruses. In this study we suggested that PheoA should be considered as a potential candidate for antiviral therapy against SARS-CoV-2 (Jimenez-Aleman et al., 2021). Second, the jasmonate biosynthetic pathway was explored employing a series of fatty acid (FA) biosynthesis mutants. It was shown that the function of the orthologue of Arabidopsis’ fatty-acid-desaturase 5 (AtFAD5) in M. polymorpha (i.e. MpFAD5) is ancient and conserved between these species separated by more than 450 million years of independent evolution. Similar to AtFAD5, MpFAD5 is required for the synthesis of 7Z-hexadecenoic acid. Consequently, in Mpfad5 mutants, the hexadecanoid pathway is blocked, dn-OPDA concentration is largely depleted and normal chloroplast development impaired. Our results demonstrate that, in Marchantia, the main source of wound-induced dn-OPDA is the hexadecanoid pathway. Remarkably, despite extremely low concentrations of dn-OPDA (the active jasmonate in Marchantia), MpCOI1-mediated responses to wounding and insect feeding can be activated in Mpfad5 mutant plants, suggesting that dn-OPDA may not be the only bioactive jasmonate and MpCOI1 ligand in Marchantia (Soriano et al., 2022). Indeed, we later identified an OPDA-like molecule derived from a C20-FA in Marchantia, which we termed C20- OPDA. This molecule accumulates upon wounding, and when applied exogenously can activate known canonical COI1-dependent and -independent jasmonate responses. Furthermore, we identified a dn- OPDA-like molecule (Δ4-dn-OPDA) and demonstrated it to be a ligand of the jasmonate receptor (MpCOI1) in M. polymorpha. By analyzing mutants defective in C20-FAs, we elucidated the biosynthetic pathways of C20-OPDA and Δ4-dn-OPDA. Moreover, using a double mutant that accumulates no Δ4-dn-OPDA and only trace amounts of dn-OPDA, we showed the additive nature of Δ4-dn-OPDA and dn-OPDA in the activation of jasmonate responses in Marchantia. This work identified a novel ligand of MpCOI1 and demonstrated that LCPUFAs are a source of bioactive jasmonates, which are essential to the plant plasticity and resilience in M. polymorpha (Kneeshaw et al., 2022).
Projektbezogene Publikationen (Auswahl)
- 2019. Omega hydroxylated JA-Ile is an endogenous bioactive jasmonate that signals through the canonical jasmonate signaling pathway. Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids, 1864 (12), 158520
Guillermo H. Jimenez-Aleman, Marilia Almeida-Trapp, Gemma Fernández-Barbero, Selena Gimenez-Ibañez, Michael Reichelt, Jyothilakshmi Vadassery, Axel Mithöfer, Julio Caballero, Wilhelm Boland and Roberto Solano
(Siehe online unter https://doi.org/10.1016/j.bbalip.2019.158520) - 2021. "SARS-CoV-2 fears green: the chlorophyll catabolite Pheophorbide-a is a potent antiviral". Pharmaceuticals, 14 (10), 1048
Guillermo H. Jimenez-Aleman, Victoria Castro, Addis Londaitsbehere, Marta Gutierrez- Rodríguez, Urtzi Garaigorta, Roberto Solano, Pablo Gastaminza
(Siehe online unter https://doi.org/10.3390/ph14101048) - 2022. An evolutionarily ancient Fatty Acid Desaturase is required for the synthesis of hexadecatrienoic acid, which is the main source of the bioactive jasmonate in Marchantia polymorpha. New Phytologist, 233, 1401
Gonzalo Soriano, Sophie Kneeshaw, Guillermo H. Jimenez-Aleman, Angel M. Zamarreño, José Manuel Franco-Zorrilla, Mª Fernanda Rey-Stolle Valcarce, Coral Barbas, Jose M. García- Mina, Roberto Solano
(Siehe online unter https://doi.org/10.1111/nph.17850) - 2022. Ligand diversity contributes to full activation of the jasmonate pathway in Marchantia polymorpha. Proceedings of the National Academy of Sciences, 119 (36), e2202930119
Sophie Kneeshaw, Gonzalo Soriano, Isabel Monte, Mats Hamberg, Ángel M. Zamarreño, Jose M. García-Mina, José Manuel Franco-Zorrilla, Nobuki Kato, Minoru Ueda, Mª Fernanda Rey-Stolle, Coral Barbas, Santiago Michavila, Selena Gimenez-Ibanez, Guillermo H. Jimenez-Alemán, and Roberto Solano
(Siehe online unter https://doi.org/10.1073/pnas.2202930119) - 2022. The jasmonic acid-amino acid conjugates JA-Val and JA- Leu are involved in rice resistance to herbivores. Plant, Cell & Environment, 45, 262
Fu, Wenjie; Jin, Gaochen; Guillermo H. Jimenez-Aleman; Wang, Xinjue; Song, Jiajin; Li, Suhua; Lou, Yonggen; Li, Ran
(Siehe online unter https://doi.org/10.1111/pce.14202)
