Silicon as a potentiater of the activity of enzymes related to the defense to rust in coffee and soybean plants / Silício como potencializador da atividade de enzimas de defesa à ferrugem em plantas de café e soja

AUTOR(ES)

Sandra Cerqueira Pereira

DATA DE PUBLICAÇÃO

2007

RESUMO

The coffee leaf rust (Hemileia vastatrix) and asian soybean rust (Phakopsora pachyrhizi) can significantly reduce yield, respectively, on coffee and soybean crops. Silicon (Si) is a beneficial element to plants because it increases host resistance to pests and diseases. In response to infection by pathogens, plants activate many mechanisms of defense such as an increase in the activity of the enzymes β-1.3-glucanases (GLU) and chitinases (QUI) that degrade fungus cell wall; phenylalanine ammonia-lyase (PAL) and peroxidases (POD) which are important in the lignification; polyphenoloxidases (PPO) that catalyzes the formation of quinones and lipoxygenases (LOX) that degrade fatty acids. In this context, the present study aimed to investigate if the application of potassium silicate (PS) can reduce rust severities on coffee and soybean plants mainly through the increase in the activity of GLU, QUI, PAL, POD, PPO and LOX. Soybean and coffee plants inoculated or not inoculated with P. pachyrhizi and H. vastatrix, respectively, were sprayed with PS. As control treatments, plants were sprayed with water and Acibenzolar-S-Methyl (ASM). The foliar applications of PS and ASM decreased rust severities on both coffee and soybean plants. The activity of GLU, QUI, PAL, POD, PPO and LOX increased upon pathogens infection. The reduction on rust severities was due to the polymerization of PS on leaf surface that possibly affected fungus penetration or somehow the viability of their reproductive structures.

ASSUNTO(S)

silicon enzimologia defesa de plantas soybean silício soja coffee plants defense café

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