Identification of transcription factors closely associated with the Citrus sinensis non-host response to Xanthomonas axonopodis pv. vesicatoria

DAURELIO, L.D.; ROMERO, M.S.; PETROCELLI, S.; MERELO, P.; TALÓN, M.; TADEO, F.; ORELLANO, E.G.

Foz do Iguaçu

Congreso; XLI Annual Meeting of the Brazilian Biochemistry and Molecular Biology Society (SBBq); 2012

Brazilian Biochemistry and Molecular Biology Society (SBBq)

Citrus is one of the most important fruit crops in the world. Citrus trees are recurrently exposed to pathogens, causing them to display the non-host defense response, a basic plant defense mechanism. The response of citrus leaves (Citrus sinensis cv. Valencia Late) to Xanthomonas axonopodis pv. vesicatoria (Xav), a pepper and tomato pathogenic bacterium, was studied through biochemical assays and cDNA microarray hybridization. This response was compared with citrus canker infection produced by Xanthomonas axonopodis pv. citri. Noticeably, citrus leaves exposed to Xav showed hypersensitive response (HR) features, an uncharacterized mechanism in citrus to date. Differentially expressed genes associated with biotic stress and cell death supported the response and symptoms observed. Moreover, 68 transcription factors (TFs) were differentially regulated by Xav in citrus leaves, including 26 from the stress-associated families AP2-ERF, bZip, Myb and WRKY. Remarkably, an in silico analysis of the distribution of expressed sequence tags revealed that 10 of these TFs, belonging to C2C2-GATA, C2H2, CCAAT, HSF, NAC and WRKY gene families, were specifically over-represented in citrus stress cDNA libraries. These TFs are novel candidate genes to regulate key steps of citrus HR. Furthermore, they could be used in future strategies of molecular breeding for citrus disease resistance.