Abstract
Plants react quickly and profoundly to changes in their environment. A sudden increase in temperature, for example, induces differential petiole growth-driven upward leaf movement (hyponastic growth) in Arabidopsis (Arabidopsis thaliana). We show that accessions that face the strongest fluctuations in diurnal temperature in their natural habitat are least sensitive for heat-induced hyponastic growth. This indicates that heat-induced hyponastic growth is a trait subject to natural selection. The response is induced with kinetics remarkably similar to ethylene- and low light-induced hyponasty in several accessions. Using pharmacological assays, transcript analysis, and mutant analyses, we demonstrate that ethylene and the photoreceptor protein phytochrome B are negative regulators of heat-induced hyponastic growth and that low light, phytochrome A, auxin, polar auxin transport, and abscisic acid are positive regulators of heat-induced hyponastic growth. Furthermore, auxin, auxin polar transport, phytochrome A, phytochrome B, and cryptochromes are required for a fast induction of heat-induced hyponastic growth.
Highlights
Plants react quickly and profoundly to changes in their environment
A positive correlation for all accessions was found in the temperature range from approximately 16°C to approximately 38°C, demonstrating that Arabidopsis petioles actively react with a differential growth-driven upward leaf movement to changes in environmental temperature (Fig. 1A)
Regulation of hyponastic growth is complex, and different environmental stimuli are integrated in the control of this differential petiole growth response in Arabidopsis
Summary
Plants react quickly and profoundly to changes in their environment. A sudden increase in temperature, for example, induces differential petiole growth-driven upward leaf movement (hyponastic growth) in Arabidopsis (Arabidopsis thaliana). We show that accessions that face the strongest fluctuations in diurnal temperature in their natural habitat are least sensitive for heatinduced hyponastic growth This indicates that heat-induced hyponastic growth is a trait subject to natural selection. Leaf angles of naturally occurring accessions that face the strongest fluctuations in diurnal temperature in their natural habitat are least sensitive to heat, suggesting that this trait is subject to natural selection. The regulation of this response was studied by a combination of pharmacological experiments, gene expression studies, and mutant analyses. We present evidence that ethylene and phytochrome B are negative regulators and that low light, phytochrome A, auxin, and abscisic acid (ABA) are positive regulators of heat-induced hyponastic growth
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