Shade avoidance: phytochrome signalling and other aboveground neighbour detection cues

Abstract

Plants compete with neighbouring vegetation for limited resources. In competition for light, plants adjust their architecture to bring the leaves higher in the vegetation where more light is available than in the lower strata. These architectural responses include accelerated elongation of the hypocotyl, internodes and petioles, upward leaf movement (hyponasty), and reduced shoot branching and are collectively referred to as the shade avoidance syndrome. This review discusses various cues that plants use to detect the presence and proximity of neighbouring competitors and respond to with the shade avoidance syndrome. These cues include light quality and quantity signals, mechanical stimulation, and plant-emitted volatile chemicals. We will outline current knowledge about each of these signals individually and discuss their possible interactions. In conclusion, we will make a case for a whole-plant, ecophysiology approach to identify the relative importance of the various neighbour detection cues and their possible interactions in determining plant performance during competition.

Phytochrome B Nuclear Bodies Respond to the Low Red to Far-Red Ratio and to the Reduced Irradiance of Canopy Shade in Arabidopsis

“…The occurrence of this type of fine control of sensitivity argues against the idea that the phyB-mediated hyponastic response to reduced irradiance is a maladaptive feature of the phyB perception system. Rather, it supports the view that the perception of neighbors involves sensing and integrating diverse signals (Pierik and de Wit, 2013).…”

Ethylene- and shade-induced hypocotyl elongation share transcriptome patterns and functional regulators

“…All organisms, including plants, assess and respond to both biotic and abiotic factors in their environments (Franklin et al, 2011;Osakabe et al, 2014;Pierik and de Wit, 2014;Pierik and Testerink, 2014;Voesenek and Bailey-Serres, 2015;Quint et al, 2016). However, unlike animals, plants cannot move away from extremes in their surrounding environment but rather rely on various plastic morphological and metabolic responses.…”

“…Young plants growing in a canopy experience changes in light quality and quantity due to neighboring plants and compete to harvest optimum light (Casal, 2013;Pierik and de Wit, 2014). When a plant cannot outgrow its neighbors, it experiences complete vegetation shade (hereafter termed shade), which, in addition to low red:far-red (R:FR) light, is marked by a significant decline in blue light and overall light quantity.…”

“…When a plant cannot outgrow its neighbors, it experiences complete vegetation shade (hereafter termed shade), which, in addition to low red:far-red (R:FR) light, is marked by a significant decline in blue light and overall light quantity. These changes initiate so-called shade-avoidance syndrome responses consisting of petiole, hypocotyl, and stem elongation, reduction of cotyledon and leaf expansion, upward movement of leaves (hyponasty), decreased branching, and increased apical dominance (Vandenbussche et al, 2005;Franklin, 2008;Casal, 2012;Pierik and de Wit, 2014). Shade-induced elongation comprises a complex network of photoreceptor-regulated transcriptional and proteinlevel regulation involving basic helix-loop-helix (bHLH) and homeodomain-leucine zipper (HD-ZIP) transcription factors and auxin, GA, and brassinosteroid (BR) hormone genes (Casal, 2012(Casal, , 2013.…”

Production and quality of strawberry cultivated under different colors of low tunnel cover

“…This fact shows that the other treatments may have caused a shading effect, which was interpreted by plants as competition for light, which stimulated vegetative growth. Since, in natural environments, the shading caused by neighboring plants change the quantity and quality of radiation which reaches shaded plants (Pierik & Wit, 2014), which when exposed to such changes in light, may adapt their morphogenesis, photosynthesis and photoprotective mechanisms (Anders & Essen, 2015). The ability of plants to perceive the environment is due to the action of specific photoreceptors sensitive to different light quality and intensity and, when exposed to different luminous quality, emit signs translated into morphophysiological changes (Casierra-Posada & Peña-Olmos, 2015), as the ones found in this study.…”