INDETERMINATE-DOMAIN 4 (IDD4) coordinates immune responses with plant-growth in Arabidopsis thaliana

Abstract
INDETERMINATE DOMAIN (IDD)/ BIRD proteins are a highly conserved plant-specific family of transcription factors which play multiple roles in plant development and physiology. Here, we show that mutation in IDD4/IMPERIAL EAGLE increases resistance to the hemi-biotrophic pathogen Pseudomonas syringae, indicating that IDD4 may act as a repressor of basal immune response and PAMP-triggered immunity. Furthermore, the idd4 mutant exhibits enhanced plant-growth indicating IDD4 as suppressor of growth and development. Transcriptome comparison of idd4 mutants and IDD4ox lines aligned to genome-wide IDD4 DNA-binding studies revealed major target genes related to defense and developmental-biological processes. IDD4 is a phospho-protein that interacts and becomes phosphorylated on two conserved sites by the MAP kinase MPK6. DNA-binding studies of IDD4 after flg22 treatment and with IDD4 phosphosite mutants show enhanced binding affinity to ID1 motif-containing promoters and its function as a transcriptional regulator. In contrast to the IDD4-phospho-dead mutant, the IDD4 phospho-mimicking mutant shows altered susceptibility to PstDC3000, salicylic acid levels and transcriptome reprogramming. In summary, we found that IDD4 regulates various hormonal pathways thereby coordinating growth and development with basal immunity.

Citation
Völz R, Kim S-K, Mi J, Rawat AA, Veluchamy A, et al. (2019) INDETERMINATE-DOMAIN 4 (IDD4) coordinates immune responses with plant-growth in Arabidopsis thaliana. PLOS Pathogens 15: e1007499. Available: http://dx.doi.org/10.1371/journal.ppat.1007499.

Acknowledgements
The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Funding for the project was provided to Prof Heribert Hirt by baseline funding project BAS/1/1062 of the King Abdullah University of Science and Technology.

Publisher
Public Library of Science (PLoS)

Journal
PLOS Pathogens

DOI
10.1371/journal.ppat.1007499

Additional Links
https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1007499

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