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Plant J. 2015 Oct;84(2):309-22. doi: 10.1111/tpj.12995.

Rhizobacterial volatiles and photosynthesis-related signals coordinate MYB72 expression in Arabidopsis roots during onset of induced systemic resistance and iron-deficiency responses.

Author information

1
Plant-Microbe Interactions, Department of Biology, Faculty of Science, Utrecht University, PO Box 800.56, 3508 TB, Utrecht, The Netherlands.
2
Department of Plant-Microbe Interactions, Max Planck Institute for Plant Breeding Research, 50829, Cologne, Germany.
3
Molecular Plant Physiology, Department of Biology, Faculty of Science, Utrecht University, PO Box 800.56, 3508 TB, Utrecht, The Netherlands.
4
Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, SE-90187, Umeå, Sweden.
5
Bioinformatics, Department of Biology, Faculty of Science, Utrecht University, PO Box 800.56, 3508 TB, Utrecht, The Netherlands.
6
The State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No. 1 West Beichen Road, Chaoyang District, Beijing, 100101, China.

Abstract

In Arabidopsis roots, the transcription factor MYB72 plays a dual role in the onset of rhizobacteria-induced systemic resistance (ISR) and plant survival under conditions of limited iron availability. Previously, it was shown that MYB72 coordinates the expression of a gene module that promotes synthesis and excretion of iron-mobilizing phenolic compounds in the rhizosphere, a process that is involved in both iron acquisition and ISR signaling. Here, we show that volatile organic compounds (VOCs) from ISR-inducing Pseudomonas bacteria are important elicitors of MYB72. In response to VOC treatment, MYB72 is co-expressed with the iron uptake-related genes FERRIC REDUCTION OXIDASE 2 (FRO2) and IRON-REGULATED TRANSPORTER 1 (IRT1) in a manner that is dependent on FER-LIKE IRON DEFICIENCY TRANSCRIPTION FACTOR (FIT), indicating that MYB72 is an intrinsic part of the plant's iron-acquisition response that is typically activated upon iron starvation. However, VOC-induced MYB72 expression is activated independently of iron availability in the root vicinity. Moreover, rhizobacterial VOC-mediated induction of MYB72 requires photosynthesis-related signals, while iron deficiency in the rhizosphere activates MYB72 in the absence of shoot-derived signals. Together, these results show that the ISR- and iron acquisition-related transcription factor MYB72 in Arabidopsis roots is activated by rhizobacterial volatiles and photosynthesis-related signals, and enhances the iron-acquisition capacity of roots independently of the iron availability in the rhizosphere. This work highlights the role of MYB72 in plant processes by which root microbiota simultaneously stimulate systemic immunity and activate the iron-uptake machinery in their host plants.

KEYWORDS:

Arabidopsis thaliana; MYB transcription factor; induced resistance; iron homeostasis; plant growth-promoting rhizobacteria; volatile organic compounds

PMID:
26307542
PMCID:
PMC5019235
DOI:
10.1111/tpj.12995
[Indexed for MEDLINE]
Free PMC Article

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