AbstractThe present PhD thesis dissertation reports new functions for Brasssinosteroids receptors controlling abiotic stress responses in Arabidopsis thaliana.
Brassinosteroids (BRs) are the steroid hormones of plants. BRs play essential roles in plant growth and development and plant adaptation to stress. In this direction, exogenous application of BRs provide crop protection against abiotic stresses, such as salt, cold or drought stress, yet the mechanisms governing these responses have remained unknown. Activation of downstream signaling components failed to provide the resistance observed with exogenous applications. The putative roles of BR receptors under stress stand out as key information for dissecting the BR-driven mechanism of stress adaptation but they have remained very unexplored. Here, we use an interdisciplinary approach, including genetics, multiomics analyses and bioinformatics, to decipher the roles of BR receptors in front of abiotic stresses such as DNA damage, osmotic stress and drought.
The results presented in this thesis uncover a role for the spatiatiotemporal control of BR signaling in response to abiotic stress. Physiological analysis of Arabidopsis roots revealed that BR receptors are required for cellular regeneration of the root stem cells after DNA damage. Moreover, the multiomic analysis of plants exposed to drought showed that the overexpression of the vascular-specific BRI1-like 3 (BRL3) receptor lead to an altered transcriptional and metabolic signature that alleviate the detrimental effects of drought and decouple drought tolerance from growth arrest. A major part of omics hallmarks found in these plants are phloem-specific.
The bioinformatic approach used to disentangle tissue-specific transcriptional control was further implemented in a web tool, expandable to any plant specie. Finally, through a structural biology approach we found a small Receptor-Like Kinase (RLK) whose interaction with BRL3 is more favorable than the canonical co-receptor BAK1. Indeed, this candidate has been recently involved in response to osmotic stress, which suggest alternative BR-activated pathways that control abiotic stress responses.
Overall, the present PhD thesis advances the roles of BR receptors to support plant growth and survival under abiotic stress. BRs paracrine signaling at the root stem cell niche and the metabolic adaptation driven from vascular tissues illustrate the importance of dissecting plant tissue-specific responses. The study presented here, also opens new windows for further investigation on mechanisms triggered by BR-receptor that contribute to plant adaptation.
|Date of Award||10 Oct 2019|
|Supervisor||Benet Gunse Forcadell (Tutor) & Ana Isabel Caño Delgado (Director)|