Focus

Our research interest is to study the mechanisms by which plants perceive and respond to their light environment, specifically in the regulation of the light-induced developmental transition that occurs during seedling deetiolation and in the regulation of growth under diurnal conditions.The primary focus of our research is to identify the dark signaling mechanisms that operate in the regulation of these plant processes, using Arabidopsis as a model system and integrating a combination of multidisciplinary experimental approaches. Our current research is focused on the study of the role of the phytochrome-interacting factor 3 (PIF3) transcription factor and PIF3-regulated signaling components.

Background

Arabidopsis Light and DarkPlants modulate their growth and development to adjust to the continuous variations in their light environment. During early development after germination in the subterranean darkness of the subsoil, seedlings adopt a skotomorphogenic or etiolated program of development, in which allocation of resources is directed toward rapid and exaggerated elongation of the hypocotyl to seek light. Once the seedling reaches the soil surface, light induces a rapid switch to a photomorphogenic or deetiolated program of development, in which etiolation is inhibited and the greening process initiates to enable light capture through photosynthesis.This rapid switch from dark to light development is called deetiolation and is essential for seedling survival after germination in the dark. Recent evidence indicates that the deetiolation switch is achieved in Arabidopsis as a result of to the antagonistic action of the photoreceptors phytochromes (phy) and the basic helix-loop-helix transcription factors Phytochrome-Interacting Factors (PIFs): PIF1, 3, 4 and 5 promote growth and maintain the etiolated state, whereas light-activated phys are strong promoters of deetiolation by targeting the PIFs to proteolytic degradation. Balance between PIF levels and active phy determine the extent of deetiolation. However, it is still largely unknown how the PIFs regulate dark growth. As part of one of our projects, we are identifying and characterizing the function of several PIF3-regulated genes in Arabidopsis during etiolation after germinating in the dark.

Arabidopsis MicroRegulation of plant growth through modulation of PIF levels has also been recently proposed to determine growth rate under diurnal conditions- that is, under photoperiodic cycles of light and dark. In these conditions, Arabidopsis hypocotyl growth reaches its maximum at the end of the night. PIF4 and PIF5 have been shown to regulate this rhythmic growth as promoters of growth in the dark in coordination with the circadian clock and hormone signals. Possible involvement of other PIFs as well as their primary regulatory mechanism and interaction with the clock still need to be investigated. To this end, and as part of a second project in our lab, we are studying the contribution of PIF3 to optimize growth under these diurnal conditions.

Funding

Current grant support to our laboratory:
Ministerio de Ciencia e Innovacion, MICINN. (E. Monte). BIO2012-31672. 2013-2015
AGAUR, Generalitat de Catalunya. (E. Monte). 2009 SGR 206. 2010-2015
Marie Curie PCIG10-GA-2011-304008. (C.Diaz). 2012-2016
Marie Curie PIRG06-GA-2009-256420. (P. Leivar). 2010-1014

LAB NEWS

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