One of the most dramatic changes in plant growth and development is the transition from life in the underground darkness after germination of the buried seed, to life in sunlight when the seedling reaches the soil surface. In Arabidopsis, seedlings in the dark have long hypocotyls, closed unexpanded cotyledons protected by an apical hook, and lack pigmentation.
Upon transition to light, seedlings switch their developmental program to adjust accordingly: the hypocotyl slows down elongation, the apical hook unfolds, cotyledons separate and expand, and chloroplasts develop and accumulate chlorophyll. Recent studies have shown that the phytochrome (phy) A and phyB photoreceptors, and the phy-interacting bHLH transcription factors PIF1 and PIF3 are involved in this process, together with the E3 ubiquitin ligase COP1. Despite increasing progress, the mechanisms operating in this dark-to-light developmental switch are still largely unknown.
The main objective of this proposal is to identify the regulatory mechanisms involved. Previous results have revealed the importance of the dark period in the regulation of this process. We propose to examine the protein and gene expression profiles during dark development in Arabidopsis seedlings to identify differentially regulated factors with a role in the dark-to-light switch.
The specific objectives are:
- identification of factors differentially expressed in dark-grown seedlings using a novel proteomics approach and through the analysis of genomic profiles; and
- characterization of the role of the new identified factors in the dark-to-light switch in development using reverse genetics and molecular approaches.
This proposal fulfils the objectives of the IRG Programme to contribute to European research and transfer the knowledge acquired by the applicant during the seven years of postdoctoral career in the US, and contributes to the objectives of the ERA to foster fundamental knowledge and basic tools for functional genomics.
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