Rapid temperature responses of photosystem II efficiency forecast genotypic variation in rice vegetative heat tolerance

John N Ferguson* (Corresponding Author), Lorna McAusland, Kellie E Smith, Adam H Price, Zoe A Wilson, Erik H Murchie

*Corresponding author for this work

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28 Citations (Scopus)
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A key target for the improvement of Oryza sativa (rice) is the development of heat-tolerant varieties. This necessitates the development of high-throughput methodologies for the screening of heat tolerance. Progress has been made to this end via visual scoring and chlorophyll fluorescence; however, these approaches demand large infrastructural investments to expose large populations of adult plants to heat stress. To address this bottleneck, we investigated the response of the maximum quantum efficiency of photosystem II (PSII) to rapidly increasing temperatures in excised leaf segments of juvenile rice plants. Segmented models explained the majority of the observed variation in response. Coefficients from these models, i.e. critical temperature (T crit ) and the initial response (m 1 ), were evaluated for their usability for forecasting adult heat tolerance, measured as the vegetative heat tolerance of adult rice plants through visual (stay-green) and chlorophyll fluorescence (ɸPSII) approaches. We detected substantial variation in heat tolerance of a randomly selected set of indica rice varieties. Both T crit and m 1 were associated with measured heat tolerance in adult plants, highlighting their usability as high-throughput proxies. Variation in heat tolerance was associated with daytime respiration but not with photosynthetic capacity, highlighting a role for the non-photorespiratory release of CO 2 in heat tolerance. To date, this represents the first published instance of genetic variation in these key gas-exchange traits being quantified in response to heat stress in a diverse set of rice accessions. These results outline an efficient strategy for screening heat tolerance and accentuate the need to focus on reduced rates of respiration to improve heat tolerance in rice.

Original languageEnglish
Pages (from-to)839-855
Number of pages17
JournalThe Plant Journal
Issue number3
Early online date4 Sept 2020
Publication statusPublished - Nov 2020

Bibliographical note

This article is protected by copyright. All rights reserved.

We are grateful to the University of Nottingham glasshouse staff for their assistance with general plant maintenance. We thank Laura Briers for supplying the photograph used in Figure 1. This article benefited substantially from the critical insight of Dr Alex Burgess. JNF is supported by the Palaeobenchmarking Resilient Agriculture Systems (PalaeoRAS) project funded by the Future Food Beacon of the University of Nottingham. EHM receives funding from the Biotechnology and Biological Sciences Research Council (BBSRC, grant no. BB/R004633/1). KES is supported by a University of Nottingham–BBSRC Doctoral Training Partnership studentship.


  • chlorophyll fluorescence
  • stay-green
  • photosynthesis
  • heath stress
  • Oryza sativa
  • high-throughput phenotyping
  • technical advance
  • C-3 PLANTS
  • heat stress


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