@Article{IPB-2523, author = {Tabassum, N. and Eschen‐Lippold, L. and Athmer, B. and Baruah, M. and Brode, M. and Maldonado‐Bonilla, L. D. and Hoehenwarter, W. and Hause, G. and Scheel, D. and Lee, J.}, title = {{Phosphorylation‐dependent control of an RNA granule‐localized protein that fine‐tunes defence gene expression at a post‐transcriptional level}}, year = {2020}, pages = {1023-1039}, journal = {Plant J}, doi = {10.1111/tpj.14573}, url = {https://dx.doi.org/10.1111/tpj.14573}, volume = {101}, abstract = {Mitogen‐activated protein kinase (MAPK) cascades are key signalling modules of plant defence responses to pathogen‐associated molecular patterns (PAMPs, e.g. bacterial flg22 peptide). The Tandem Zinc Finger Protein 9 (TZF9) is an RNA‐binding protein that is phosphorylated by two PAMP‐responsive MAPKs, MPK3 and MPK6. We mapped the major phosphosites in TZF9 and showed their importance for controlling in vitro RNA‐binding activity, in vivo flg22‐induced rapid disappearance of TZF9‐labelled processing body‐like structures and TZF9 protein turnover. Microarray analysis showed a strong discordance between transcriptome (total mRNA) and translatome (polysome‐associated mRNA) in the tzf9 mutant, with more mRNAs associated to ribosomes in the absence of TZF9. This suggests that TZF9 may sequester and inhibit translation of subsets of mRNAs. Fittingly, TZF9 physically interacts with poly(A)‐binding protein 2 (PAB2), a hallmark constituent of stress granules – a site for stress‐induced translational stalling/arrest. TZF9 even promotes stress granule assembly in the absence of stress. Hence, MAPKs may control defence gene expression post‐transcriptionally through release from translation arrest within TZF9‐PAB2‐containing RNA granules or perturbing PAB2 functions in translation control (e.g. in the mRNA closed‐loop model of translation).} }