Differential expression of the brassinosteroid receptor-encoding BRI1 gene in Arabidopsis

Abstract Brassinosteroid (BR)-regulated growth and development in Arabidopsis depends on BRASSINOSTEROID INSENSITIVE 1 (BRI1), the BR receptor that is responsible for initiating the events of BR signalling. We analysed the temporal and spatial regulation of BRI1 expression using stable transgenic lines that carried BRI1 promoter:reporter fusions. In both seedlings and mature plants the tissues undergoing elongation or differentiation showed elevated BRI1 gene activity, and it could be demonstrated that in the hypocotyl this was accompanied by accumulation of the BRI1 transcript and its receptor protein product. In seedlings the BRI1 promoter was also found to be under diurnal regulation, determined primarily by light repression and a superimposed circadian control. To determine the functional importance of transcriptional regulation we complemented the severely BR insensitive bri1-101 mutant with a BRI1-luciferase fusion construct that was driven by promoters with contrasting specificities. Whereas the BRI1 promoter-driven transgene fully restored the wild phenotype, expression from the photosynthesisassociated CAB3 and the vasculature-specific SUC2 and ATHB8 promoters resulted in plants with varying morphogenic defects. Our results reveal complex differential regulation of BRI1 expression, and suggest that by influencing the distribution and abundance of the receptor this regulation can enhance or attenuate BR signalling

Methods for modeling brassinosteroid-mediated signaling in plant development

Mathematical modeling of biological processes is a useful tool to draw conclusions that are contained in the data, but not directly reachable, as well as to make predictions and select the most efficient follow-up experiments. Here we outline a method to model systems of a few proteins that interact transcriptionally and/or posttranscriptionally, by representing the system as Ordinary Differential Equations and to study the model dynamics and stationary states. We exemplify this method by focusing on the regulation by the brassinosteroid (BR) signaling component BRASSINOSTEROID INSENSITIVE1 ETHYL METHYL SULFONATE SUPPRESSOR1 (BES1) of BRAVO, a quiescence-regulating transcription factor expressed in the quiescent cells of Arabidopsis thaliana roots. The method to extract the stationary states and the dynamics is provided as a Mathematica code and requires basic knowledge of the Mathematica software to be executed.D.F. and M.I. acknowledge support from the Ministerio de Economía y Competitividad (Spain) and FEDER (EU) through grant FIS2015-66503-C3-3-P and from the Generalitat de Catalunya through Grup de Recerca Consolidat 2014 SGR 878. AIC-D acknowledges financial support from the Spanish Ministry of Economy and Competitiveness, through the ‘Severo Ochoa Programme for Centres of Excellence in R&D’ 2016–2019 (SEV-2015-0533). AIC-D is a recipient of a BIO2013-43873 grant from the Spanish Ministry of Economy and Competitiveness and European Research Council, ERC Consolidator Grant (ERC-2015-CoG – 683163).Peer reviewe

Molecular mapping and cloning of genes and QTLs

The barley genome is comprised of more than 39,000 high-confidence genes, which represent many valuable targets for breeders as well as plant researchers trying to understand the genetic network controlling the various grass species, especially members of the Triticeae tribe including barley, wheat, and rye. The present chapter provides an overview of how past activities with barley mutants, markers, and genetic maps have laid the foundation for the present physical map based on the barley genome. We also describe how this new genome sequence resource can be integrated with mapping approaches to facilitate the cloning of genes and quantitative trait loci (QTL). Although the cost of genomic sequencing is likely to decrease, we assume that mapping of genes deficient in mutants will remain an important approach for gene identification. We present a comprehensive list of barley genes identified up to 2017