Abstract

ROBLEDO-BURITICA, Jacobo; ANGEL-GARCIA, Carolina  and  CASTANO-ZAPATA, Jairo. Environmental Scanning Electron Microscopy of the Infection Process of Fusarium solani f. sp. passiflorae in Seedlings of Passionfruit ( Passiflora edulis f. flavicarpa ). Rev. acad. colomb. cienc. exact. fis. nat. [online]. 2017, vol.41, n.159, pp.213-220. ISSN 0370-3908.  https://doi.org/10.18257/raccefyn.471.

Environmental scanning electron microscopy (ESEM) was performed in seedlings of Passiflora edulis f. flavicarpa inoculated with Fusarium solani f. sp. passiflorae (teleomorph: Haematonectria haematococca) causal agent of passionfruit collar rot. Inoculations were carried out every 24 h until the seventh day and from this day until the fifteenth the interval of inoculation was 72 h. The pathogen isolated in PDA media was placed on the surface of the collar through the modified test-tube screening methodology. Epidermis of collar, stem, and leaves and longitudinal sections of collar and stem were observed. After 24 h of inoculation, conidia and dense septate mycelium were observed over the epidermis of the stem and the collar, respectively. Hypertrophy and cell wall degradation of the vascular tissues were also found during this period. Five days after the inoculation macroconidia were formed from monophialides in the aerial mycelium on the stem. Ten days after inoculation, xylem and pith cells of the collar were colonized by hyphae, inclusions, and mature sporodoquia over the stem surface. Hyphae colonization started six days after inoculation on stomata and thirteen days after inoculation monophialides with in situ microconidia were observed over the surface of the leaves. Based on the evidence and previous studies, internal hyphae colonization of F. solani f. sp. passiflorae concentrates on the collar area and the damages of the cells indicate an extracellular enzymatic activity of the fungus. The incubation and latent periods of F. solani f. sp. passiflorae were 1.4 and 4 days, respectively. © 2017. Acad. Colomb. Cienc. Ex. Fis. Nat.

Keywords : Plant diseases; fungal diseases; Passifloraceae; collar rot; scanning microscopy.

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