Expressão de genes em Phytophthora nicotianae que codificam proteínas indutoras de respostas de defesa em plantas

Abstract

The study of the Citros-Phytophthora nicotianae interaction was focused into the Citros Milenium project, and it has generated an ESTs database of Phytophthora nicotianae IAC 095 strain (PP/CitEST) after in planta induction and in vitro subculture for 40 times. The objectives of this study were to adequate the methodology to growth and citros Phytophthora nicotianae separation of life cycle phases and analyze its genes expression that codify extracellular proteins inductors of defense response in plants, using a quantitative PCR (RT-PCR). Orange fruits were inoculated with discs containing P. nicotianae mycelia. After infection, the pathogen was purified during the culture containing antibiotics and 4 phases of its life cycle it was obtained: Zoospores, mycelia, mycelia with empty sporangium. cDNA was synthesized from the mRNA obtained from the phases and the gene expression was analyzed by the qRT-PCR. The adequate condition to cultivate the citros P. nicotianae in vitro, aiming the phases separation of its life cycle, is among liquid carrot distributed in erlenmeyers, a 25º C under a constant light. For five out of the eight studied genes (CBEL, Ric1, Bip, Car and Transglutaminase) the expression profile was similar, presenting a higher expression in mycelia and mycelia with empty sporangium phases. The Megaspermina protein was more expressed in zoosporos than in mycelia, empty and full sporangium. On the other hand, the proteins 14-3-3 and Sintaxina were more expressed in mycelia than the other studied phases.