Understanding how DELLA-mediated transcription controls GA-responsive growth and development in Arabidopsis

Lead Research Organisation: Rothamsted Research
Department Name: Unlisted


In recent years there have been major advances in our understanding of how the plant hormone, gibberellin (GA) is perceived and this signal transduced, leading to changes in growth and development. The DELLA proteins (DELLAs) are central to this signalling cascade, and act as repressors of GA-responsive growth. GA signalling relieves the repression exerted through DELLAs by targeting their degradation through an ubiquitin-proteasome mediated process, which is well understood. In contrast, our understanding of the role of DELLAs in repressing GA-responsive growth is very limited. Although it is thought that DELLAs act as transcriptional regulators, their mode of action is not clear and no target genes have been identified. The work outlined in this proposal is aimed at improving our understanding of the role of DELLAs and their downstream target genes in regulating GA-responsive growth in Arabidopsis. Our proposed strategy involves using a combination of microarray and chromatin immunoprecipitation experiments to identify early GA-responsive genes that are the primary targets of the DELLAs. We will focus on specific GA-responsive tissues, rather than the whole plant. To uncover the role of these DELLA target genes in regulating GA-responsive growth, we will use a reverse genetics-based strategy. Based on the probable absence of a canonical DNA-binding domain in the DELLAs, it is likely that they regulate the expression of GA-responsive genes through their interaction with other transcription factors. To identify these components we will perform yeast two-hybrid screens using a DELLA bait construct. Putative DELLA interactors will be confirmed by testing the interactions in vivo. Furthermore, their roles in GA signalling will be assessed by analysing the phenotype of knock-out mutants.


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