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Prof. Dr. Miguel A. Blázquez Group Leader at the Institute of Plant Molecular and Cellular Biology in Valencia, Spain, and Senior Researcher of the Spanish Scientific Research Council. Miguel Ángel Blázquez is Group Leader at the Institute of Plant Molecular and Cellular Biology in Valencia since 2001, when he became Staff Scientist of the Spanish Research Council. He studied Chemistry in the Autonomous University of Madrid and obtained his PhD in Biochemistry in 1995 for his work on a new regulatory mechanism of yeast glycolysis that has resulted later in the improvement of yeast industrial fermentation. As a postdoc, he joined the Plant Biology Lab at The Salk Institute in San Diego (California), where he studied the interaction between light and hormones in the control of flowering time, under the supervision of Prof. Detlef Weigel. Work in the Blázquez Lab is focused in the architecture of the signaling circuits that control early stages of plant development, and how plants integrate multiple signals to render the most appropriate response in each situation. He was appointed EMBO Young Investigator in 2003 and spent a sabbatical year in the Parcy Lab (CEA-CNRS, Grenoble, France). |
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Plant survival depends on the optimal use of resources under largely
variable environmental conditions. Among the different mechanisms that
have been proposed to mediate the balance between growth,
differentiation and stress responses, the regulation of
transcriptional activity by DELLA proteins stands out. In Arabidopsis,
DELLA accumulation has been shown to promote defence against biotic
and abiotic stress and impair cell division and expansion, while loss
of DELLA function has been associated to increased plant size and
sensitivity towards stress. Given that DELLA protein stability is
dependent on gibberellin (GA) levels, and GA metabolism is strongly
influenced by the environment, DELLAs are thought to relay
environmental information to the transcriptional programs that
regulate growth and stress responses. However, DELLAs predate the
emergence of GA metabolism, since they are found in the genomes of
early-diverging non-vascular plants, while the active GAs and the GA
receptor appear only in vascular plants.
We have investigated the role of the only DELLA in the liverwort
Marchantia polymorpha and found that it is preferentially expressed in
the meristematic regions, and that increased DELLA levels cause
reduced thallus growth. DELLA overexpression also impairs gemma
dormancy and delays gametangiophore formation, resembling the
phenotype of Mppif mutants. In addition, both genotypes show higher
survival rates under oxidative stress thanks to an increased flavonoid
production. Our results suggest that the function of the ancestral
DELLA in the first land plants would already involve the coordination
between growth and stress responses. Furthermore, we have analyzed
DELLA structure and performed targeted DELLA-TF interactome studies in
M. polymorpha and several other species, combined with complementation
analyses in Arabidopsis dellaKO mutants. Our results indicate that
DELLA’s interactome was established early during land plant evolution,
given that most of DELLA-TF interactions are conserved. In summary, we
propose that DELLA proteins already behaved as hubs in transcriptional
networks in the ancestor of all land plants, while the strict
conservation of their molecular and biological functions over the past
450 M years provides a measure of the high biological relevance of
DELLA proteins for plant survival.
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