Laura Leticia Barrera-Necha

Microscopic study of the morphology and metabolic activity of Fusarium oxysporum f. sp. gladioli treated with Jatropha curcas oil and derivatives

The fungus Fusarium oxysporum f. sp. gladioli is one of the main pathogenic microorganisms of the ornamental genus Gladiolus. The attack of this microorganism includes corms and different plant phenological stages. In this study, different microscopic techniques and fluorochromes were used to evaluate the effect of J. curcas oil and acylglycerides, namely trilinolein, triolein, monomyristin and dimyristin, on the morphology, membrane integrity (%), viability (%) and germination (%) of F. oxsporum f sp. gladioli. Phase-contrast optical photomicrographs and scanning microscopy showed that J. curcas oil and the triglycerides triolein and trilinolein caused the formation of numerous vacuoles, alterations in the morphology of the outer covering of the mycelium and conidia, and inhibition of membrane activity in the fungus during 24 h of incubation. The fluorochromes used detected no permanent damage to the viability of the conidia. The high germination percentage of the conidia of Fusarium oxysporum f. sp. gladioli indicates that the damage caused by the application of the treatments was fungistatic rather than fungicidal and did not cause cell death.

Synthesis and Characterization of Chitosan Nanoparticles Loaded Botanical Extracts with Antifungal Activity on Colletotrichum gloeosporioides and Alternaria species

In this study, chitosan nanoparticles (CSNPs) and chitosan nanoparticles- botanical extracts: EEA-CSNPs (ethanolic blueberry extract added chitosan nano-particles) and EMN-CSNPs (extract methanol of nanche added chitosan nano-particles) were characterized and evaluated in vitro ongrowth of Alternaria alternata isolated from Fig and Rosemary and Colletotrichum gloeosporioides isolated from Papaya and Soursop. From particle size distribution characteriza-tion, the size of nanoparticles increased after EEA incorporation. On the other hand, the smallest value of Z-average particle size was for the EMN-CSNPs. Zeta potential value decreased for CSNPs and EEA-CSNPs. However, when EMN is incorporated to CSNPs, the value is increased. From the results, it can be seen that the most stable suspension was EMN-CSNPs. After incorporation of Byrsonima crassifolia to CSNPs, no changes were observed in characteristic absorption bands for the FTIR spectra. However, after Vaccinium corymbosum incorporation to the CSNPs, changes were seen. For in vitro evaluation, CSNPs without EEA caused the total germination and sporulation inhibition of A. alternata from Rosemary. Incorporation of EMN to CSNPs improved the control of C. gloeosporioides with amycelial growth inhibition of 79% isolated from papaya and 82% isolated from soursop. In both isolated there were total germination inhibition. Overall, a synergistic effect between the chitosan and EMN was observed.