Shade avoidance


Author for correspondence:
Keara A. FranklinTel: +44 116 2525302Fax: +44 116 2522791Email:



 Summary930V.Crosstalk in shade avoidance signalling939
I.Introduction931VI.Future perspectives940
II.Shade avoidance responses932 Acknowledgements940
III.Photoreceptor regulation of shade avoidance932 References940
IV.Molecular mechanisms in shade avoidance signalling934   


The threat to plant survival presented by light limitation has driven the evolution of highly plastic adaptive strategies to either tolerate or avoid shading by neighbouring vegetation. When subject to vegetational shading, plants are exposed to a variety of informational signals, which include altered light quality and a reduction in light quantity. The former includes a decrease in the ratio of red to far-red wavelengths (low R : FR) and is detected by the phytochrome family of plant photoreceptors. Monitoring of R : FR ratio can provide an early and unambiguous warning of the presence of competing vegetation, thereby evoking escape responses before plants are actually shaded. The molecular mechanisms underlying physiological responses to alterations in light quality have now started to emerge, with major roles suggested for the PIF (PHYTOCHROME INTERACTING FACTOR) and DELLA families of transcriptional regulators. Such studies suggest a complex interplay between endogenous and exogenous signals, mediated by multiple photoreceptors. The phenotypic similarities between physiological responses habitually referred to as ‘the shade avoidance syndrome’ and other abiotic stress responses suggest plants may integrate common signalling mechanisms to respond to multiple perturbations in their natural environment.