Publikation
Schulze, A.; Zimmer, M.; Mielke, S.; Stellmach, H.; Melnyk, C. W.; Hause, B.; Gasperini, D. Shoot-to-root translocation of the jasmonate precursor 12-oxo-phytodienoic acid (OPDA) coordinates plant growth responses following tissue damage bioRxiv (2019) DOI: 10.1101/517193
Multicellular organisms rely upon the movement of signaling molecules across cells, tissues and organs to communicate among distal sites. In plants, herbivorous insects, necrotrophic pathogens and mechanical wounding stimulate the activation of the jasmonate (JA) pathway, which in turn triggers the transcriptional changes necessary to protect plants against those challenges, often at the expense of growth. Although previous evidence 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 consequences of their relocation remain unknown. Here, we demonstrated that endogenous JA species generated after shoot injury translocate to unharmed roots via the phloem vascular tissue in Arabidopsis thaliana. By wounding wild-type shoots of chimeric plants and by quantifying the relocating compounds from their JA-deficient roots, we uncovered that the JA-Ile precursor 12-oxo-phytodienoic acid (OPDA) is a mobile JA species. Our data also showed that OPDA is a primary mobile compound relocating to roots where, upon conversion to the bioactive hormone, it induces JA-mediated gene expression and root growth inhibition. Collectively, our findings reveal the existence of long-distance transport of endogenous OPDA which serves as a communication molecule to coordinate shoot-to-root responses, and highlight the importance of a controlled distribution of JA species among organs during plant stress acclimation.
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.
Publikation
Acosta, I. F.; Gasperini, D.; Chételat, A.; Stolz, S.; Santuari, L.; Farmer, E. E. Role of NINJA in root jasmonate signaling Proc Natl Acad Sci USA 110, 15473-15478, (2013) DOI: 10.1073/pnas.1307910110
Wound responses in plants have to be
coordinated between organs so that locally reduced growth in a wounded
tissue is balanced by appropriate growth elsewhere in the body. We used a
JASMONATE ZIM DOMAIN 10 (JAZ10) reporter to screen for mutants affected
in the organ-specific activation of jasmonate (JA) signaling in
Arabidopsis thaliana seedlings. Wounding one cotyledon activated the
reporter in both aerial and root tissues, and this was either disrupted
or restricted to certain organs in mutant alleles of core components of
the JA pathway including COI1, OPR3, and JAR1. In contrast, three other
mutants showed constitutive activation of the reporter in the roots and
hypocotyls of unwounded seedlings. All three lines harbored mutations in
Novel Interactor of JAZ (NINJA), which encodes part of a repressor
complex that negatively regulates JA signaling. These ninja mutants
displayed shorter roots mimicking JA-mediated growth inhibition, and
this was due to reduced cell elongation. Remarkably, this phenotype and
the constitutive JAZ10 expression were still observed in backgrounds
lacking the ability to synthesize JA or the key transcriptional
activator MYC2. Therefore, JA-like responses can be recapitulated in
specific tissues without changing a plant’s ability to make or perceive
JA, and MYC2 either has no role or is not the only derepressed
transcription factor in ninja mutants. Our results show that the role of
NINJA in the root is to repress JA signaling and allow normal cell
elongation. Furthermore, the regulation of the JA pathway differs
between roots and aerial tissues at all levels, from JA biosynthesis to
transcriptional activation.