Indução de resistência em mudas de cacaueiro contra Moniliophthora perniciosa por produto à base de mananoligossacarídeo fosforilado

Abstract

Protecting the cacao crop by using biotic and abiotic products, seeking to induce plant resistance, is an important strategy, which can broaden the effectiveness of cacao witches' broom control. The objective of this work was to investigate the effect of doses and times of application of a mannanoligosaccharide based product (Agro-Mos®) on cacao seedlings against Moniliophthora perniciosa, as well as its direct toxicity to the pathogen and to characterize some biochemical mechanisms involved in plant defense response. It was found that Agro-Mos® conferred greater protection for cacao seedlings against witches' broom in relation to acibenzolar S-methyl, ASM. The in vitro mycelial growth of M. perniciosa was completely inhibited by Agro-Mos® and Recop® (copper oxichloride) at dose intervals of 3.6 to 7.0 mL.L-1, and 0.1 to 0.2 g.L-1, respectively. There were increased activities of chitinases, β-1,3-glucanases, guaiacol peroxidases, polyphenol oxidases, without changes in the content of lignin and total soluble phenolics in plants treated with ASM, Agro-Mos® or Experimental Agro-Mos® (without Cu++). The disease incidence reduction due to Agro-Mos®, associated with its in vitro toxic effect and the activation of some enzymes related to plant defense response, suggests that Agro-Mos® has a direct effect against the fungus and is also activating plant defense mechanisms.