Indutores de resistência no manejo da ferrugem e cercosporiose do cafeeiro (Coffea arabica): análises bioquímicas e moleculares

Abstract

Rust and brown eye spot, caused by Hemileia vastatrix and Cercospora coffeicola, respectively, are the main fungal diseases of coffee plants in Brazil. Considering the necessity of developing alternative products for its control, we aimed in this work at evaluating the effect of phosphite sources and formulations based on by-products of coffee and citrus industry in the control of these diseases, under greenhouse and field conditions. Subsequently, we selected the Greenforce CuCa (formulation based on a by-produtcs of the coffee industry) and manganese phosphite in order to study its effects over the coffee plant/ C. caffeicola and coffee plant/ H. vasatrix interactions, respectively. We verified that phosphite sources and formulations based on by-products of coffee and citrus industry provided control over rust and brown eye spot on adult coffee plants or on seedlings. Under field conditions, we observed that the associations of phosphite sources and formulation based on a by-produtcs of the coffee industry with fungicide controlled rust and brown eye spot, being more effective when compared to the separate application of the products, in addition to providing higher foliar retention and higher yield. In the biochemical and molecular analyses, we proved that the Greenforce CuCa induced the increase in the transcription of CaPR1, CaGT, LOX and PAL genes and, also, provided an increment in the activity of enzymes peroxidase (POX), ascorbate peroxidase (APX), catalase (CAT), superoxide dismutase (SOD), phenylalanine ammonia-lyase (PAL) and polyphenol oxidase (PPO) in coffee seedlings inoculated and not inoculated with C. coffeicola. The manganese phosphite induced defense responses on the coffee seedlings, since it increased the transcription of POX, CAT, GLU and PAL genes in plants not inoculated with the pathogen and, also, provided an increment in the activity of enzymes APX, SOD and PPO in plants inoculated and not inoculated with H. vastatrix. With the results observed, we indicate that the use of phosphites or formulation based on a by-produtcs of the coffee industry can be used in management coffee plant diseases.