Publikation
Wasternack, C.; Hause, B.; BFP1: One of 700 Arabidopsis F-box proteins mediates degradation of JA oxidases to promote plant immunity Mol. Plant 17, 375-376, (2024) DOI: 10.1016/j.molp.2024.02.008
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Publikation
Abukhalaf, M.; Proksch, C.; Thieme, D.; Ziegler, J.; Hoehenwarter, W.; Changing turn-over rates regulate abundance of tryptophan, GS biosynthesis, IAA transport and photosynthesis proteins in Arabidopsis growth defense transitions BMC Biol. 21, 249, (2023) DOI: 10.1186/s12915-023-01739-3
Background
Shifts in dynamic equilibria of the abundance of cellular molecules in plant-pathogen interactions need further exploration. We induced PTI in optimally growing Arabidopsis thaliana seedlings for 16 h, returning them to growth conditions for another 16 h.
Methods
Turn-over and abundance of 99 flg22 responding proteins were measured chronologically using a stable heavy nitrogen isotope partial labeling strategy and targeted liquid chromatography coupled to mass spectrometry (PRM LC–MS). These experiments were complemented by measurements of mRNA and phytohormone levels.
Results
Changes in synthesis and degradation rate constants (Ks and Kd) regulated tryptophane and glucosinolate, IAA transport, and photosynthesis-associated protein (PAP) homeostasis in growth/PTI transitions independently of mRNA levels. Ks values increased after elicitation while protein and mRNA levels became uncorrelated. mRNA returned to pre-elicitation levels, yet protein abundance remained at PTI levels even 16 h after media exchange, indicating protein levels were robust and unresponsive to transition back to growth. The abundance of 23 PAPs including FERREDOXIN-NADP( +)-OXIDOREDUCTASE (FNR1) decreased 16 h after PAMP exposure, their depletion was nearly abolished in the myc234 mutant. FNR1 Kd increased as mRNA levels decreased early in PTI, its Ks decreased in prolonged PTI. FNR1 Kd was lower in myc234, mRNA levels decreased as in wild type.
Conclusions
Protein Kd and Ks values change in response to flg22 exposure and constitute an additional layer of protein abundance regulation in growth defense transitions next to changes in mRNA levels. Our results suggest photosystem remodeling in PTI to direct electron flow away from the photosynthetic carbon reaction towards ROS production as an active defense mechanism controlled post-transcriptionally and by MYC2 and homologs. Target proteins accumulated later and PAP and auxin/IAA depletion was repressed in myc234 indicating a positive effect of the transcription factors in the establishment of PTI.
Publikation
Menna, A.; Dora, S.; Sancho-Andrés, G.; Kashyap, A.; Meena, M. K.; Sklodowski, K.; Gasperini, D.; Coll, N. S.; Sánchez-Rodríguez, C.; A primary cell wall cellulose-dependent defense mechanism against vascular pathogens revealed by time-resolved dual transcriptomics BMC Biol. 19, 161, (2021) DOI: 10.1186/s12915-021-01100-6
Background:
Cell walls (CWs) are protein-rich polysaccharide matrices essential for plant growth and environmental acclimation. The CW constitutes the first physical barrier as well as a primary source of nutrients for microbes interacting with plants, such as the vascular pathogen Fusarium oxysporum (Fo). Fo colonizes roots, advancing through the plant primary CWs towards the vasculature, where it grows causing devastation in many crops. The pathogenicity of Fo and other vascular microbes relies on their capacity to reach and colonize the xylem. However, little is known about the root-microbe interaction before the pathogen reaches the vasculature and the role of the plant CW during this process.
Results:
Using the pathosystem Arabidopsis-Fo5176, we show dynamic transcriptional changes in both fungus and root during their interaction. One of the earliest plant responses to Fo5176 was the downregulation of primary CW synthesis genes. We observed enhanced resistance to Fo5176 in Arabidopsis mutants impaired in primary CW cellulose synthesis. We confirmed that Arabidopsis roots deposit lignin in response to Fo5176 infection, but we show that lignin-deficient mutants were as susceptible as wildtype plants to Fo5176. Genetic impairment of jasmonic acid biosynthesis and signaling did not alter Arabidopsis response to Fo5176, whereas impairment of ethylene signaling did increase vasculature colonization by Fo5176. Abolishing ethylene signaling attenuated the observed resistance while maintaining the dwarfism observed in primary CW cellulose-deficient mutants.
Conclusions:
Our study provides significant insights on the dynamic root-vascular pathogen interaction at the transcriptome level and the vital role of primary CW cellulose during defense response to these pathogens. These findings represent an essential resource for the generation of plant resistance to Fo that can be transferred to other vascular pathosystems.Keywords: Arabidopsis, Fusarium oxysporum, Ralstonia solanacearum, plant-pathogen interaction, dual-time coursetranscriptomics, cellulose, ethylene, defense response
Publikation
Bassal, M.; Abukhalaf, M.; Majovsky, P.; Thieme, D.; Herr, T.; Ayash, M.; Tabassum, N.; Al Shweiki, M. R.; Proksch, C.; Hmedat, A.; Ziegler, J.; Lee, J.; Neumann, S.; Hoehenwarter, W.; Reshaping of the Arabidopsis thaliana Proteome Landscape and Co-regulation of Proteins in Development and Immunity Mol. Plant 13, 1709-1732, (2020) DOI: 10.1016/j.molp.2020.09.024
Proteome remodeling is a fundamental adaptive response, and proteins in
complexes and functionally related proteins are often co-expressed.
Using a deep sampling strategy we define core proteomes of Arabidopsis thaliana
tissues with around 10 000 proteins per tissue, and absolutely quantify
(copy numbers per cell) nearly 16 000 proteins throughout the plant
lifecycle. A proteome-wide survey of global post-translational
modification revealed amino acid exchanges pointing to potential
conservation of translational infidelity in eukaryotes. Correlation
analysis of protein abundance uncovered potentially new tissue- and
age-specific roles of entire signaling modules regulating transcription
in photosynthesis, seed development, and senescence and abscission.
Among others, the data suggest a potential function of RD26 and other
NAC transcription factors in seed development related to desiccation
tolerance as well as a possible function of cysteine-rich receptor-like
kinases (CRKs) as ROS sensors in senescence. All of the components of
ribosome biogenesis factor (RBF) complexes were found to be co-expressed
in a tissue- and age-specific manner, indicating functional promiscuity
in the assembly of these less-studied protein complexes in Arabidopsis. Furthermore, we characterized detailed proteome remodeling in basal immunity by treating Arabidopsis
seeldings with flg22. Through simultaneously monitoring
phytohormone and transcript changes upon flg22 treatment, we obtained
strong evidence of suppression of jasmonate (JA) and JA-isoleucine
(JA-Ile) levels by deconjugation and hydroxylation by IAA-ALA RESISTANT3
(IAR3) and JASMONATE-INDUCED OXYGENASE 2 (JOX2), respectively, under
the control of JASMONATE INSENSITIVE 1 (MYC2), suggesting an
unrecognized role of a new JA regulatory switch in pattern-triggered
immunity. Taken together, the datasets generated in this study present
extensive coverage of the Arabidopsis proteome in various biological scenarios, providing a rich resource available to the whole plant science community.
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.