The arabidopsis zinc finger proteins SRG2 and SRG3 are positive regulators of plant immunity and are differentially regulated by nitric oxide

Beimi Cui, Shiwen Xu, Yuan Li, Saima Umbreen, Debra Frederickson Matika, Bo Yuan, Jihong Jiang, Fengquan Liu, Qiaona Pan, Gary J. Loake

Research output: Contribution to journalArticlepeer-review

Abstract

Nitric oxide (NO) regulates the deployment of a phalanx of immune responses, chief among these is the activation of a constellation of defence-related genes. However, the underlying molecular mechanisms remain largely unknown. The zinc finger transcription factor (ZF-TF), S-nitrosothiol (SNO) Regulated 1 (SRG1), is a central target of NO bioactivity during plant immunity. Here we characterise the remaining members of the SRG gene family.

Both SRG2 and especially SRG3, were positive regulators of salicylic acid-dependent plant immunity. Informatively, analysis of SRG single, double and triple mutants, implied SRG family members have additive functions in plant immunity and surprisingly are under reciprocal regulation.

SRG2 and SRG3 localised to the nucleus and functioned as EAR domain-dependent transcriptional repressors: NO abolished this activity for SRG3 but not SRG2. Consistently, loss of GSNOR function, resulting in increased (S)NO levels, fully suppressed the disease resistance phenotype established from SRG3 but not SRG2 over-expression. Remarkably, SRG3 but not SRG2 was S-nitrosylated in vitro and in vivo.

Our findings suggest the SRG family has separable functions in plant immunity and surprisingly, these ZF-TFs exhibit reciprocal regulation. Remarkably, through neo-functionalization, the SRG family has evolved to become differentially regulated by the key, immune-related redox cue, NO.
Original languageEnglish
Number of pages16
JournalNew Phytologist
Early online date9 Oct 2020
DOIs
Publication statusE-pub ahead of print - 9 Oct 2020

Keywords

  • disease resistance
  • nitric oxide
  • plant immunity
  • S-nitrosylation
  • redox regulation
  • zinc finger
  • arabidopsis thaliana

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