Light signals generated by vegetation shade facilitate acclimation to low light in shade-avoider plants |
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Authors: | Luca Morelli Sandi Paulii Wenting Qin Ariadna Iglesias-Sanchez Irma Roig-Villanova Igor Florez-Sarasa Manuel Rodriguez-Concepcion Jaime F Martinez-Garcia |
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Institution: | 1. Institute for Plant Molecular and Cell Biology (IBMCP), CSIC-UPV, València 46022, Spain;2. Centre for Research in Agricultural Genomics (CRAG) CSIC-IRTA-UAB-UB, Campus UAB Bellaterra, Barcelona 08193, Spain;3. Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig Lluís Companys 23, Barcelona 08010, Spain |
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Abstract: | When growing in search for light, plants can experience continuous or occasional shading by other plants. Plant proximity causes a decrease in the ratio of R to far-red light (low R:FR) due to the preferential absorbance of R light and reflection of FR light by photosynthetic tissues of neighboring plants. This signal is often perceived before actual shading causes a reduction in photosynthetically active radiation (low PAR). Here, we investigated how several Brassicaceae species from different habitats respond to low R:FR and low PAR in terms of elongation, photosynthesis, and photoacclimation. Shade-tolerant plants such as hairy bittercress (Cardamine hirsuta) displayed a good adaptation to low PAR but a poor or null response to low R:FR exposure. In contrast, shade-avoider species, such as Arabidopsis (Arabidopsis thaliana), showed a weak photosynthetic performance under low PAR but they strongly elongated when exposed to low R:FR. These responses could be genetically uncoupled. Most interestingly, exposure to low R:FR of shade-avoider (but not shade-tolerant) plants improved their photoacclimation to low PAR by triggering changes in photosynthesis-related gene expression, pigment accumulation, and chloroplast ultrastructure. These results indicate that low R:FR signaling unleashes molecular, metabolic, and developmental responses that allow shade-avoider plants (including most crops) to adjust their photosynthetic capacity in anticipation of eventual shading by nearby plants.Vegetation proximity light signals inform shade-avoider plants to adjust their photosynthetic capacity in anticipation of eventual shading by nearby plants. |
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