CRoSh · “Chromatin Re-organization during Shade Avoidance”

“Chromatin Re-organization during Shade Avoidance”

Light is vital for plants because it is their source of energy and provides important information about the environment. Quality and quantity of light change continuously and plants developed systems to sense these changes, which can be rapid (within minutes) or slow (seasonal changes) and adapt their growth to maximize photosynthesis and improve fitness. One example of growth response driven by changes in the light spectrum is the shade avoidance response. Shade avoidance happens when plants grow in dense vegetation and leaves reflect the Far-Red component of sunlight creating a shaded environment characterized by a low ratio between Red and Far Red light (LRFR). LRFR is not tolerated by plants loving full sunlight, where the Red/ Far Red ratio is high (HRFR), such as our model organism Arabidopsis thaliana. Arabidopsis deploys a series of growth responses to escape from this situation, which includes the elongation of stem-like organs to position the leaves towards the sun and outside the shade. The architectural changes are initiated by the deactivation of the photoreceptor phyB by LRFR, which triggers the accumulation/activation of a class of transcription factors called PIFs. PIFs start the remodelling of the expression of numerous genes, that includes genes involved in the biosynthesis of the hormone auxin. The increase of auxin levels is the limiting step for the elongation phenotype typical of the shade avoidance response. Until now, researchers have focused mostly on the characterization of the activity of PIFs and other TFs controlled by auxin levels, but a description of the chromatin landscape of the regulatory regions involved in this process was lacking and this is why we decided to initiate this project. Better understand the molecular mechanisms regulating gene expression underlying shade avoidance response is important for two main reasons: 1) shade avoidance is a beautiful example of how an external stimulus sensed by an organism starts a molecular cascade, which is translated into a physiological response, that facilitate the plants' adaptation to new environmental conditions. Given that the mechanisms of genic response are quite conserved, knowledge acquired from this response could be applied to other environmental conditions, species or organisms. 2) In monoculture, plants tend to be grown densely to improve food production, but this triggers shade avoidance responses that have an impact on traits that affect the final yield, such as the acceleration of flowering, decrease of biomass, and increase of sensitivity to the attack of pathogens and herbivores. Hence modern agriculture needs to solve the conflict between rearrangements of organ architecture to improve light harvesting and maintain yield stability, which can be achieved by deciphering the molecular mechanisms controlling these processes.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз