Structural and Functional Characterization of Plant Homeodomain-Leucine Zipper Transcription Factors

CHAN RL

Aguas de Lindoia- Brasil

Congreso; 55º Congresso Brasileiro de Genética .; 2009

Sociedad Brasilera de Genética

Structural and Functional Characterization of Plant Homeodomain-Leucine Zipper Transcription FactorsChan, Raquel LíaInstituto de Agrobiotecnología del Litoral-Universidad Nacional del Litoral, CONICET, CC 242 Ciudad Universitaria, 3000, Santa Fe, Argentina   Transcription factors (TFs) are clue elements in the regulation of signal transduction pathways. Arabidopsis and rice present in their genome about 1500 transcription factors encoding genes which have been classified in several families according to structural and functional features. The homeodomain-leucine zipper (HD-Zip) TFs, unique to plants, constitute one of these families. These proteins (29 in Arabidopsis), classified in four subfamilies, have a specific DNA-binding domain (HD) associated to a leucine zipper (LZ).Our research group is devoted to the functional characterization of HD-Zip TFs from different species including sunflower, Medicago truncatula and Arabidopsis thaliana. The expression of the encoding genes is regulated by phytorhormones and also by biotic and abiotic factors such as drought, salinity, insect?s attack, and extreme temperatures. We applied a strategy consisting in the isolation of selected genes, the cloning of them in suitable vectors to transform Arabidopsis plants, the obtaining of homozygous transgenic plants and a detailed analysis of these plants using a series of techniques (phenotypic analysis, expression analysis, microarrays, histochemistry, etc.). Finally, when a heterologous system was used, the molecular data obtained was corroborated by transient transformation followed by varied analyses.This strategy allowed us to determine in which pathways are involved several HD-Zip proteins as well as the role they play in the adaptive response to environmental stresses. Moreover, when they are constitutively expressed in transgenic plants, most of these TFs generate differential phenotypes conferring tolerance to varied stresses. In this sense, some of them became potential biotechnological tools to improve agronomic crops in their behavior in front of drought, salinity, freezing temperatures and insect?s attacks.Since all the tested HD-Zip proteins bind in vitro the same DNA sequence and present similar expression patterns, we investigated some structural features outside the conserved domains as putative reasons for the differential behaviors. We performed chimerical constructs and transform plants with them. A novel hypothesis regarding the complex relationships determining each TF? function will be presented regarding the results obtained with the new transgenic plants.