Abstract
Low, but non‐freezing, temperatures have negative effects on plant growth and development. Despite some molecular signalling pathways being known, the mechanisms causing different responses among genotypes are still poorly understood. Photosynthesis is one of the processes that are affected by low temperatures. Using an automated phenotyping platform for chlorophyll fluorescence imaging the steady state quantum yield of photosystem II (PSII) electron transport (ΦPSII) was measured and used to quantify the effect of moderately low temperature on a population of Arabidopsis thaliana natural accessions. Observations were made over the course of several weeks in standard and low temperature conditions and a strong decrease in ΦPSII upon the cold treatment was found. A genome wide association study identified several quantitative trait loci (QTLs) that are associated with changes in ΦPSII in low temperature. One candidate for a cold specific QTL was validated with a mutant analysis to be one of the genes that is likely involved in the PSII response to the cold treatment. The gene encodes the PSII associated protein PSB27 which has already been implicated in the adaptation to fluctuating light.
Highlights
Low, but non-freezing, temperatures negatively affect the growth and development of most plants (Mckersie & Leshem, 1994)
Comparing all measurements of ΦPSII made on that day (15DAS) compared to the last day of the control treatment (13DAS), the average ΦPSII of the accessions was decreased by 23.1% (Table 1), with differences in ΦPSII reduction ranging from 11.6 to 46.6% depending on the genotype
In this study the effect of cold on natural accessions of Arabidopsis thaliana was examined by the means of CF imaging of photosynthesis efficiency
Summary
Non-freezing temperature, differences in leaf biomass related traits, such as leaf size and other leaf morphological traits have been observed in A. thaliana (Armstrong, Logan, & Atkin, 2006; Gorsuch, Pandey, & Atkin, 2010) While these traits could be used for the quantification of the effect of cold, to allow the identification of differences between genotypes, their measurements need to be very precise, demanding high numbers of replicates, as the effect size is relatively small. A solution to this would be the use of image-based traits, for example the quantum yield of the photosystem II (PSII) electron transport under dark-adapted conditions (maximum quantum yield, Fv/Fm) or under steady-state illumination (the operating quantum yield of PSII, ΦPSII) These are integrative, primary physiological traits that have been found to be highly responsive to different stresses (Baker & Rosenqvist, 2004; Maxwell & Johnson, 2000), including low temperature exposure (Gray, Hope, Qin, Taylor, & Whitehead, 2003; Hurry, Krol, Oquist, & Huner, 1992). Several loci specific to the low temperature condition that influence ΦPSII are identified, and mutants were used to confirm the relevance of candidate genes residing at these loci
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