University of Cambridge > > Plant Sciences Departmental Seminars > Made in the shade: light signals, phytochromes and plant development

Made in the shade: light signals, phytochromes and plant development

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Re-scheduled from 8 February 2007

The phytochromes are a family of reversibly photochromic plant photoreceptors that perceive spatial and temporal informational signals and initiate appropriate adaptive developmental strategies. One such strategy involves the phytochrome-mediated perception of the far-red radiation (700-800 nm) reflected/scattered from the leaves of nearby vegetation, providing an early warning of potential shading, and leading to a series of developmental responses, the ‘shade-avoidance syndrome’, that can result in the overgrowth of those neighbours. Upon sensing a reflected far-red light signal, a shade-avoiding plant very rapidly exhibits enhanced elongation growth. If the rapid elongation strategy is unsuccessful, and the far-red light signal persists, then other aspects of the shade-avoidance syndrome cause accelerated flowering and early production of seeds, enhancing the probability of survival. Despite its adaptive significance, little is known about the molecular events that connect light perception with increased elongation growth in shade avoidance. Using microarrays, we have shown that an early event following the perception of the far-red light signal is the altered expression of numerous genes. For several of these genes, altered expression in response to far-red light signals is gated by the circadian clock. Furthermore, the rapid shade avoidance elongation growth response is gated by the circadian clock, being most apparent around (subjective) dusk. Several of the far-red-responsive genes are essential for the normal display of the rapid elongation growth response. Preliminary evidence suggests that one of the earliest molecular events in the transduction of the far-red rich light signal is the stabilisation of PIFs; phytochrome-interacting transcriptional regulators.

This talk is part of the Plant Sciences Departmental Seminars series.

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