Deciphering the vascular role of brassinosteroids receptors in Arabidopsis and Sorghum.

Abstract

The present Ph.D. thesis dissertation reports molecular genetics analysis of plants towards the identification of: i) new roles for BRL3 receptor in controlling plant growth and abiotic stress responses in Arabidopsis thaliana, ii) new players of BRL3-mediated thermomorphogenesis in Arabidopsis thaliana, and iii) roles for BRI1 receptor in embryonic root development of Sorghum bicolor._x000D_ Brassinosteroids (BRs) are essential phytohormones that play key roles in plant growth, development, and abiotic stress responses. The BR signaling pathway is one of the best studied in plants. Several BR receptors have been identified, but key roles for BRL3, a vascular-enriched BR receptor, have just only started to be elucidated. BRs are of great importance in crops, as many BR-related mutants exhibit desired traits for agricultural species. This Ph.D. thesis work implements an interdisciplinary approach of genetics, -omics, bioinformatics, and physiological assays to uncover a new role for BRL3 controlling plant thermomorphogenic adaptations and to identify novel components of the BRL3 receptor pathway in the control of thermomorphogenesis. Furthermore, the roles of BR receptor SbBRI1 in the monocotyledonous crop Sorghum bicolor have been elucidated._x000D_ To uncover the mechanisms for BR-mediated control of hypocotyl elongation under high temperatures, a suppressor screening of brl3-2 plants has been done (Chapter 2). Genetics and metabolomics studies revealed that BRL3 performs a role in carbon allocation along the plant vasculature and phloem gating in the root (Chapter 3). Finally, by adapting well-established Arabidopsis thaliana techniques to the less-characterized cereal Sorghum bicolor, we were able to identify and characterize the SbBRI1 receptor. The analysis in Sorghum bicolor supports the conserved roles for BRI1 receptors in cell division and elongation, in meristem development, and overall root growth._x000D_ Overall, the results of this Ph.D. thesis open a new window to develop new climate-smart crops.

Date of Award	18 Sept 2023
Original language	English
Supervisor	Ana Isabel Caño Delgado (Director)