By accomplishing the proposed goals of the ERC CoG grant IDRICA we have identified and characterized a number of key molecular components of the Brassinosteroid (BR)-signaling pathway, which is essential for plant adaptation to drought and eleveted temperatures. In Objective 1. The local function of BRL3 receptors have been characterised in Arabidopsis, we has discovered that vascular brassinosteroid receptors BRL3 confer drought-resistant plants without penalising drought (Fabregas et al., Nat Comms 2018). In addition, we obtained unprecedented results on the identification of novel conditional phenotypes for brl3 mutants to different abiotic stresses, including elevated temperatures and increased CO2 levels. We found that brl3 mutants phenotypes can be recovered when the receptor are localised to the vascular phloem cells (Gupta., et al., Nat Plants; under revision). These experimental results not only change the paradigm for our present understanding of BR signaling in plants but also demonstrate the working hypothesis of the ERC CoG proposing that a vascular (stem) cell-specific signalling might be able to uncouple growth from adaptation to stress in the plant. In the years to come, engineering vascular cell-specific signaling pathways stands as a unique opportunity to improve plant adaptation to stress and impact in agriculture towards the solution of the food security crisis in the current climate change globally.
Also in the context of the ERC CoG, we have developed novel tools for plant data integration and analysis and developed software tools for this purpose (Betegon,et al., Plant Journal 2019). We have found a tight correlation between transcriptional responses of plants with increased BR receptor BRL3 levels and the accumulation of osmoprotectant metabolites (sugars and aminoacids) in the root by metabolomics analysis (Fabregas et al., Nat Comms 2018). To this aim, we are also developing a new software tool (TOTEM, a web tool that calculates tissue-enrichment values over an input gene list and visual representation. The latest developments in this direction include the singe-cell transcriptomics resolution that has also been achieved in the context of Obj. 2 of this ERC grant that will be publicly available here
Lozano, Coleto et al., ms. under preparation(se abrirá en una nueva ventana). These new tools will be instrumental for the accomplishment of the genetic and chemicals screenings proposed in Objective 2.
In Objetive 3, we have transferred our fundamental findings in Arabidopsis to cereal Sorghum. We identified and characterised mutants for BRI1-like family member in Sorghum. We carried genetic analysis and established the set up microscopical and multi -omics tools for the analysis of root using embryonic roots. The initial characterisation of the BRI1 receptor mutants is under review (Rico-Medina et al., submitted). Finally, our greatest efforts in Sorghum are oriented towards the establishment of gene transformation protocols in order to lead genomic edition of most interested genes to improve drought resistance.
Overall, our proposal advance novel mechanisms for the molecular understanding of plants to drought stress adaptation mediated by brassinosteroid hormones, while transfers all the technologies and knowhow into agricultural value in order to improve cereal production in climate change scenarios using sorghum as a model.
