Phylogenetic and expression analyses of WRKY transcription factors provide insights into sunflower

GIACOMELLI JI; RIBICHICH KF; DEZAR CA; CHAN RL

San Miguel de Tucumán

Congreso; XLV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2009

SAIB

WRKY transcription factors phylogenetic and expression analyses reveal a novel cladein Asteraceae Giacomelli JI, Ribichich KF, Dezar CA, Chan, RLLaboratorio de Biotecnología Vegetal - IAL - CONICET / FBCB - UNL Sunflower is a highly economically important crop for which genomic and molecular biology tools are very limited and whose genome sequence is unknown. Transcription factors (TFs) are key proteins regulating many signal transduction pathways. WRKY TFs are involved in the plant abiotic and biotic stress responses. The goal of this survey was to identify and characterize sunflower WRKY TFs through in silico and expression gene analyses.Performing a bioinformatic approach, the existence of 97 putative sunflower WRKY members derived from NCBI EST database was estimated. Phylogenetic trees constructed with WRKY domains indicated that these genes could be classified in the 7 groups assigned to Arabidopsis and resolved a novel clade with traits apparently specific to Asteraceae. Expression patterns of one selected member of each group indicated that these genes are regulated by biotic and abiotic stresses as well as by the hormones associated to these stresses. One of them, HAWRKY5,  is differentially expressed in sunflower lines tolerant to Sclerotinia infection.This study indicates that Asteraceae WRKY family has suffered a particular diversification, which could be the source of specific new functions. On the other hand, the sunflower WRKYs would play a role in the biotic stress response and could be markers of tolerance to necrotrophic pathogens, useful for the improvement of this crop.