Resumo

GONZALEZ-PENA FUNDORA, Dianevys et al. Inhibitory activity of a chitosan polymer on vegetative growth and asexual reproduction of an isolate of Phytophthora palmivora Butler. Rev. Protección Veg. [online]. 2016, vol.31, n.2, pp. 99-106. ISSN 2224-4697.

The aim was to evaluate the effect of chitosan on the vegetative growth and the asexual reproductive stages of the life cycle of Phytophthora palmivora Butler. Solutions of different chitosan concentrations, ranging from 0.5 to 2.5 g.l-1, were mixed with V8 culture media prior to add into Petri dishes, where a mycelial disc of the isolate was then inoculated. Morphocultural aspects and radial growth were evaluated when colonies from the control treatment reached the edge of the plates. The colony diameter of the isolate decreased with increases of chitosan levels in the culture medium, and the colony morphocultural pattern was altered showing irregular edges and sandy appearance. However, the hypha diameters observed under an optical microscope did not differ from the control treatment. Low polymer concentrations (0.5 g.l-1) stimulated sporangium production, while this was reduced by increases of chitosan levels. Sporangium length/width ratio was not affected by the compound concentration. In addition, the indirect sporangium germination was inhibited at 1g.l-1, and an aberrated zoospores movement was observed, with less speed at 0.5 g.l-1 of the polymer. Moreover, the cyst germination process was stopped after 3 hours of incubation with 0.5 g.l-1 of chitosan.

Palavras-chave : Phytophthora palmivora; chitosan; sporulation.

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