Changes in light intensity reveal a major role for carbon balance in Arabidopsis responses to high temperature

Plant, Cell & Environment 2011

François Vasseur, Florent Pantin, Denis Vile

High temperature (HT) is a major limiting factor for plant productivity. Because some responses to HT, notably hyponasty, resemble those encountered in low light (LL), we hypothesized that plant responses to HT are under the control of carbon balance. We analysed the interactive effects of HT and irradiance level on hyponasty and a set of traits related to plant growth in natural accessions of Arabidopsis thaliana and mutants affected in heat dissipation through transpiration (NCED6‐OE, ost2) and starch metabolism (pgm). HT induced hyponasty, reduced plant growth and modified leaf structure. LL worsened the effects of HT, while increasing light restored trait values close to levels observed at control temperature. Leaf temperature per se did not play a major role in the observed responses. By contrast, a major role of carbon balance was supported by hyponastic growth of pgm, as well as morphological, physiological (photosynthesis, sugar and starch contents) and transcriptional data. Carbon balance could be a common sensor of HT and LL, leading to responses specific of the shade avoidance syndrome. Hyponasty and associated changes in plant traits could be key traits conditioning plant performance under competition for light, particularly in warm environments.

Hyponastic growth response to high temperature (HT) and light intensity of four Arabidopsis accessions and the complemented line at ERECTA (LER). Leaf angle is the average of six values measured within 2 weeks after the beginning of light treatments on plants grown at 20°C under moderate light (ML) intensity (175 µmolm−2s−1; white bars), and at HT (30°C) under low (LL) (70 µmolm−2s−1; black bars), ML (175 µmolm−2s−1; dark grey bars) and high light (HL) intensity (330 µmolm−2s−1; light grey bars). Bars are means ± SE (n=6–10). Letters indicate significant differences following Kruskal–Wallis non‐parametric test (P<0.05).

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