Molecular Cloning and Functional Characterization of ERF Transcription Factor Genes in Papaya

Papaya is a tropical fruit of high nutritional value, and Mexico is the world’s largest exporter of this important commodity. Diseases caused by pathogens are major constraints in the production of this crop. In our laboratory, we have identified three genes homologous to the Ethylene Response Factor (ERF) family of transcription factors (TFs) in papaya (CpERF1, CpERF3 and CpERF4). The predicted proteins of these genes showed the typical AP2/ERF DNA binding domain of the ERF family and are homologous to others plant ERF-TFs involved in disease resistance. The aims of the present study are: a) to evaluate the expression of these CpERF genes in response to biotrophic pathogens, as well as plant hormones involved in disease resistance, b) to characterize their activity as transcription factors, and c) to evaluate the effect of their overexpression in disease resistance using tobacco as a model plant. So far, we have isolated and characterized the full cDNAs of CpERF1, CpERF3 and CpERF4 and generated T1 transgenic tobacco plants overexpressing these genes in order to assess their function in disease resistance. The results of this work will extend the knowledge of the ERF family in tropical plants and may assist the genetic improvement of papaya.