BIANNUALREPORT2012-2013

Group Structure

Group Leader: Jaume Martínez (ICREA Research Professor)
Postdoctoral Researchers: Jordi Bou Torrent (until June 2012), Christiane Then (until April 2013), Nicolás Cifuentes Esquivel (March 2013 – June 2013)
PhD Students: Merce Salla (until April 2012), Nicolás Cifuentes (until February 2013), Marçal Gallemí (until December 2013), Maycon Bevilaqua (March – August 2013) , María José Molina
Master Students: Laura Lorenzo (September 2012 – June 2013), Daniela Vargas (since November 2013)
Undergrad or Master Students: Maria Àngels Peso (July – August 2012)

Summary

We are interested in understanding how plants, after perceiving vegetation proximity, change development to compete for their main and basic resource: light. Plants respond to plant proximity by either avoiding it or tolerating it. In shade avoiding species, these responses are known as the shade avoidance syndrome (SAS). We are analyzing the molecular and genetic mechanisms behind the shade avoidance syndrome (SAS) responses in the model plant Arabidopsis thaliana, that involve the modulation of pre-existing complex transcriptional networks by specific photoreceptors. After identifying several genetic components known to participate in the SAS transcriptional network, we have suggested that they are organized forming functional modules. We have also established the participation of specific components of the nuclear pore complex (NPC) in the SAS regulation. Particularly, we propose that a component of the NPC, DRACULA2 (DRA2), might have a dual role in SAS regulation: (i) a transport-dependent effect in the translocation of SAS-regulatory molecules, and (ii) a transport-independent effect that affects the transcription of shade-regulated genes. In addition of studying A. thaliana, we are also employing Cardamine hirsuta, a close relative of A. thaliana, as a model system to understand shade tolerance. We are carrying out comparative analyses between C. hirsuta and A. thaliana to address the genetic and molecular basis for differences in shade avoidance vs. shade tolerant species.

Research Projects

• ATHB4 project.ATHB4 and its close relative HAT3 (both encoding HD-ZIP class II factors) are SAS regulators in A. thaliana. We aim to better understand the molecular mechanism of action of ATHB4 during the SAS regulation. Since ATHB4 seems to be mainly a transcriptional repressor, these experiments will help to better understand the role of transcriptional repression in plants and, specifically, within the SAS regulation.
• DRACULA2 project. We have characterized the Arabidopsis mutant dracula2 (dra2), which encodes a putative nucleoporin. We plan to deepen into the hypothesis that DRA2 might have a specific role in connecting the nuclear pore complex (NPC) with chromatin regions of shade-regulated genes.
• Cardamine project. In a recent forward genetic screen, we have identified putative Cardamine hirsuta mutant seedlings with a shade avoidance gain (shag) phenotype, a finding that suggests that the lack of hypocotyl response to simulated shade in this species is likely caused by the acquisition of mechanisms of suppression of the hypocotyl elongation by plant proximity. We aim to identify the molecular nature of these shag mutations.
• Shade-metabolism project. We aim to deepen into the crosstalk of light perception and plant metabolism by exploring (i) what transcriptional regulators participate in the light-control of metabolic pathways producing carotenoids and isoprenoids in plastids, and (ii) how these plastid metabolites affect light signaling.

Selected Publications

Bou-Torrent J., Salla-Martret M., Brandt R., Musielak T., Palauqui J.-C., Martinez-Garcia J.F., Wenkel S.
ATHB4 and HAT3, two class II HD-ZIP transcription factors, control leaf development in Arabidopsis
(2012) Plant Signaling and Behavior, vol. 7 (11), pp 1382-1387

Brandt R., Salla-Martret M., Bou-Torrent J., Musielak T., Stahl M., Lanz C., Ott F., Schmid M., Greb T., Schwarz M., Choi S.-B., Barton M.K., Reinhart B.J., Liu T., Quint M., Palauqui J.-C., Martinez-Garcia J.F., Wenkel S.
Genome-wide binding-site analysis of REVOLUTA reveals a link between leaf patterning and light-mediated growth responses
(2012) Plant Journal, vol. 72 (1), pp. 31-42

Galstyan A., Bou-Torrent J., Roig-Villanova I., Martinez-Garcia J.F.
A dual mechanism controls nuclear localization in the atypical basic-helix-loop-helix protein PAR1 of Arabidopsis thaliana
(2012) Molecular Plant, vol. 5 (3), pp. 669-677

Reymond M.C., Brunoud G., Chauvet A., Martinez-Garcia J.F., Martin-Magniette M.-L., Moneger F., Scutt C.P.
A Light-Regulated Genetic Module Was Recruited to Carpel Development in Arabidopsis following a Structural Change to SPATULA
(2012) Plant Cell, vol. 24 (7), pp. 2812-2825

Cifuentes-Esquivel N., Bou-Torrent J., Galstyan A., Gallemi M., Sessa G., Salla Martret M., Roig-Villanova I., Ruberti I., Martinez-Garcia J.F.
The bHLH proteins BEE and BIM positively modulate the shade avoidance syndrome in Arabidopsis seedlings
(2013) Plant Journal, vol. 75 (6), pp. 989-1002