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Publikationen - Molekulare Signalverarbeitung

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Publikation

Mielke, S.; Zimmer, M.; Meena, M. K.; Dreos, R.; Stellmach, H.; Hause, B.; Voiniciuc, C.; Gasperini, D.; Jasmonate biosynthesis arising from altered cell walls is prompted by turgor-driven mechanical compression Sci. Adv. 7, eabf0356, (2021) DOI: 10.1126/sciadv.abf0356

Despite the vital roles of jasmonoyl-isoleucine (JA-Ile) in governing plant growth and environmental acclimation, it remains unclear what intracellular processes lead to its induction. Here, we provide compelling genetic evidence that mechanical and osmotic regulation of turgor pressure represents a key elicitor of JA-Ile biosynthesis. After identifying cell wall mutant alleles in KORRIGAN1 (KOR1) with elevated JA-Ile in seedling roots, we found that ectopic JA-Ile resulted from cell nonautonomous signals deriving from enlarged cortex cells compressing inner tissues and stimulating JA-Ile production. Restoring cortex cell size by cell type–specific KOR1 complementation, by isolating a genetic kor1 suppressor, and by lowering turgor pressure with hyperosmotic treatments abolished JA-Ile signaling. Conversely, hypoosmotic treatment activated JA-Ile signaling in wild-type plants. Furthermore, constitutive JA-Ile levels guided mutant roots toward greater water availability. Collectively, these findings enhance our understanding on JA-Ile biosynthesis initiation and reveal a previously undescribed role of JA-Ile in orchestrating environmental resilience.
Bücher und Buchkapitel

Mielke, S.; Gasperini, D.; Plant–Insect Bioassay for Testing Arabidopsis Resistance to the Generalist Herbivore Spodoptera littoralis (Champion, A. & Laplaze, L., eds.). Methods Mol. Biol. 2085, 69-78, (2020) ISBN: 978-1-0716-0142-6 DOI: 10.1007/978-1-0716-0142-6_5

Jasmonates are essential engineers of plant defense responses against many pests, including herbivorous insects. Herbivory induces the production of jasmonic acid (JA) and its bioactive conjugate jasmonoyl-l-isoleucine (JA-Ile), which then triggers a large transcriptional reprogramming to promote plant acclimation. The contribution of the JA pathway, including its components and regulators, to defense responses against insect herbivory can be evaluated by conducting bioassays with a wide range of host plants and insect pests. Here, we describe a detailed and reproducible protocol for testing feeding behavior of the generalist herbivore Spodoptera littoralis on the model plant Arabidopsis thaliana and hence infer the contribution of JA-mediated plant defense responses to a chewing insect.
Publikation

Schulze, A.; Zimmer, M.; Mielke, S.; Stellmach, H.; Melnyk, C. W.; Hause, B.; Gasperini, D.; Wound-Induced Shoot-to-Root Relocation of JA-Ile Precursors Coordinates Arabidopsis Growth Mol. Plant 12, 1383-1394, (2019) DOI: 10.1016/j.molp.2019.05.013

Multicellular organisms rely on the movement of signaling molecules across cells, tissues, and organs to communicate among distal sites. In plants, localized leaf damage activates jasmonic acid (JA)-dependent transcriptional reprogramming in both harmed and unharmed tissues. Although it has been indicated that JA species can translocate from damaged into distal sites, the identity of the mobile compound(s), the tissues through which they translocate, and the effect of their relocation remain unknown. Here, we found that following shoot wounding, the relocation of endogenous jasmonates through the phloem is essential to initiate JA signaling and stunt growth in unharmed roots of Arabidopsis thaliana. By employing grafting experiments and hormone profiling, we uncovered that the hormone precursor cis-12-oxo-phytodienoic acid (OPDA) and its derivatives, but not the bioactive JA-Ile conjugate, translocate from wounded shoots into undamaged roots. Upon root relocation, the mobile precursors cooperatively regulated JA responses through their conversion into JA-Ile and JA signaling activation. Collectively, our findings demonstrate the existence of long-distance translocation of endogenous OPDA and its derivatives, which serve as mobile molecules to coordinate shoot-to-root responses, and highlight the importance of a controlled redistribution of hormone precursors among organs during plant stress acclimation.
Publikation

Mielke, S.; Gasperini, D.; Interplay between Plant Cell Walls and Jasmonate Production Plant Cell Physiol. 60, 2629-2637, (2019) DOI: 10.1093/pcp/pcz119

Plant cell walls are sophisticated carbohydrate-rich structures representing the immediate contact surface with the extracellular environment, often serving as the first barrier against biotic and abiotic stresses. Notably, a variety of perturbations in plant cell walls result in upregulated jasmonate (JA) production, a phytohormone with essential roles in defense and growth responses. Hence, cell wall-derived signals can initiate intracellular JA-mediated responses and the elucidation of the underlying signaling pathways could provide novel insights into cell wall maintenance and remodeling, as well as advance our understanding on how is JA biosynthesis initiated. This Mini Review will describe current knowledge about cell wall-derived damage signals and their effects on JA biosynthesis, as well as provide future perspectives.
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