SOS for plant stress – the role of singlet oxygen signaling in plant responses to heat and drought stress

Matthew Terry, University of Southampton; Haruko Okamoto, University of Sussex
Rationale: 

Climate change provides a major challenge for plants as they cope with increases in abiotic stresses such as high or low temperature and drought. These conditions will negatively affect responses to biotic stresses caused by insect herbivores and pathogens, and contribute to the ongoing problem of providing sufficient food for an increasing World population (1). Temperature stress and drought can result in the production of reactive oxygen species including singlet oxygen, which signals to the rest of the plant that it is in a stressful environment. Seedling development is a particularly sensitive time during the plant life cycle and seedling damage is a major cause of crop loss. We have shown that singlet oxygen production in seedlings has a similar transcriptional signature to heat stress (2) and we hypothesise that singlet oxygen signalling from the chloroplast sends an SOS signal to the seedling that permits acclimation to environmental stresses. In this project we will test this hypothesis by examining the ability of Arabidopsis mutants (e.g. 3) compromised in SOS to withstand different stress regimes including heat and drought. We will then use our Arabidopsis findings to investigate the SOS response in important crop species including wheat and rice.

 

Methodology: 

The laboratory model plant Arabidopsis thaliana will be used to test whether seedlings of mutants with altered singlet oxygen signalling show altered acclimation responses to various environmental stresses such as high and low temperature, drought and high light (where chloroplast signalling or singlet oxygen signalling has been shown to be important in mature plants). We have a number of mutants already available to do this including double and triple mutants including ex1, ex2 (3), pub4-6, and our own, as yet unpublished mutant, saf7, that will allow us to investigate the epistatic relationship between these key genes in singlet oxygen signalling. We will also perform the reciprocal experiments to test whether these stresses activate singlet oxygen responses in seedlings. Analysis of stress responses will include a range of physiological measurements as well as analysis of the transcriptional response to stresses using real-time qPCR. Singlet oxygen production will be monitored by imaging using the fluorescent reporter Singlet Oxygen Sensor Green. For experiments with wheat and rice, we will first establish the extent of the singlet oxygen response in seedlings using the same seedling growth conditions used for Arabidopsis and then examine this response under the same set of stress conditions.

 

Location: 
School of Biological Sciences, University of Southampton
Training: 

The INSPIRE DTP programme provides comprehensive personal and professional development training alongside extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial/policy partners. The student will be registered at the University of Southampton and hosted at the School of Biological Sciences (Life Sciences building 85). Specific training will include:

The student will be working in a research team and participate in weekly laboratory meetings to present their results and discuss emerging ideas. There will also be fortnightly online meetings with both supervisors. Students will be given opportunities to present their work within the School of Biological Sciences, and at national and international meetings. They will be trained in a wide range of physiological responses to assess plant stress physiology including growth and pigment synthesis (chlorophylls and carotenoids); analysis of gene expression by real-time quantitative PCR, and fluorescence microscopy to determine singlet oxygen production.

 

Eligibility & Funding Details: 

Please see https://inspire-dtp.ac.uk/how-apply for details.

 

Background Reading: 
  1. Wheeler & von Braun (2013) Climate change impacts on global food security. Science 341, 508-13.
  2. Page, McCormac, Smith & Terry (2017) Singlet oxygen initiates a plastid signal controlling photosynthetic gene expression. New Phytol 213, 1168–80.
  3. Wagner, Przybyla, op den Camp, Kim, Landgraf, Lee, Würsch, Laloi, Nater, Hideg & Apel (2004) The genetic basis of singlet oxygen-induced stress responses of Arabidopsis thaliana. Science 306, 1183– 5.

 

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