Christian Danve M. Castroverde

  • May 1, 2018

Date & Location: May 1, 2018, at 12p; Room 168 Plant Biology Building

Subject: Mechanistic insights into the effect of elevated temperature on salicylic acid-mediated plant immunity

Abstract: It is well known that climatic factors (such as temperature and humidity) have a significant influence on plant disease development; the underlying molecular mechanisms, however, are only starting to be unraveled. We have recently reported that elevated temperature enhances Pseudomonas syringae infection in Arabidopsis plants by suppressing the accumulation of the defense hormone salicylic acid (SA) and expression of the SA biosynthetic gene ISOCHORISMATE SYNTHASE 1 (ICS1) (Huot et al. 2017, Nat Commun).

Here, we report that elevated temperature also compromises the expression of SYSTEMIC ACQUIRED RESISTANCE DEFICIENT 1 (SARD1) and CALMODULIN-BINDING PROTEIN 60g (CBP60g) – two genes encoding master transcription factors required for pathogen-induced expression of ICS1. Remarkably, overexpression of CBP60g was sufficient to restore ICS1 gene induction and SA accumulation at elevated temperature during P. syringae infection, concomitant with increased resistance to bacterial multiplication and disease symptom production. In contrast, overexpression of ICS1 was not sufficient to restore SA levels or disease resistance at elevated temperature. This suggests that CBP60g controls multiple temperature-sensitive components of SA biosynthesis and plant immunity. Moreover, global transcriptome analyses revealed that a significant suite of defense-related CBP60g target genes, including EDS5, were downregulated at elevated temperature. EDS5 is required for SA accumulation and, interestingly, its gene expression was restored in CBP60g-overexpressing plants.

We propose a model for how elevated temperature compromises SA production and immunity in Arabidopsis. This model could stimulate future research to disentangle the profound influence of temperature on immunity and disease in a variety of crop species.

Christian Danve M. Castroverde is a post-doc in the lab of Sheng Yang He.