Antimicrobial activity of methyl cis-7-oxo deisopropyldehydroabietate on Botrytis cinerea and Lophodermium seditiosum: ultrastructural observations by transmission electron microscopy

Abstract

Aims: To study the antifungal activity of methyl cis-7-oxo-deisopropyldehydroabietate (MCOD) against phytopathogenic fungi, Botrytis cinerea and Lophodermium seditiousm. The effect of the compound was studied by transmission electron microscopy (TEM) and the composition of sterols on both treated and untreated cultures was determined. Methods and Results: MCOD was tested at concentrations in the range 0AE003-0AE5% by the agar plate dilution method. The radial growth of the colonies treated with MCOD was measured against colonies from untreated cultures. The radial growth of colonies of both fungi and the spore germination of B. cinerea were partially or completely inhibited. Fragments of active growing colonies treated and untreated with MCOD were submitted to the conventional procedure for ultrastructural observation by TEM. Observations by TEM on colonies of B. cinerea and L. seditiosum under 0AE1% MCOD revealed several autophagic-like vacuoles, morphological alterations on lomasome and lipid accumulations in the apical zone of hyphae of both fungi. Observations on spore germination of B. cinerea revealed the presence of strongly stained lipid accumulations retained by vacuoles at the cell periphery of young hyphae. The sterol composition of B. cinerea and L. seditiosum was determined on MCOD treated and untreated cultures by gas-chromatography ⁄ mass-spectrometry (GC-MS) with molecular ions and fragmentation patterns characteristics of ergosterol (M + 396) and dihydroergosterol (M + 398) in both fungi. Conclusions: The morphological alterations are consistent with an unspecific mode of action of MCOD causing inhibition of normal growth or damaging the fungi cells. TEM observations suggest a mechanism of resistance based on the retention of MCOD by the lipid accumulation. Significance and Impact of the Study: The results obtained in the present work afforded a better understanding of the mode of action of a resin acid derivative on phytopathogenic fungi. The inhibition growth of both fungi by MCOD demonstrates the antifungal activity of this compound and the interest on further in vivo studies, in order to evaluate its potential as a benign alternative to conventional fungicides.

Effect of lipopeptides of antagonistic strains ofBacillus subtilison the morphology and ultrastructure of the cucurbit fungal pathogenPodosphaera fusca

“…All of these alterations result in the plasmolysis of P. fusca cells and ultimately produce the morphological damage visible in conidia (Bélanger et al. 1995; Feio et al. 2002; Wang et al.…”

“…The antagonistic interaction between antifungal compounds and fungal conidia seems to share a common feature, which involves the induction of ultrastructural damages linked to irreversible morphological modifications, all of which result in irreversible damage to conidia, rendering them unviable (Askary et al 1997;Wurms et al 1999;Feio et al 2002;Wang et al 2002). In a previous study, we reported the ability of two strains of B. subtilis, UMAF6614 and UMAF6639, to manage cucurbit powdery mildew disease elicited by P. fusca in in vitro and in planta assays (Romero et al 2004).…”

A Cytochrome P450 Involved in the Metabolism of Abietane Diterpenoids by Pseudomonas abietaniphila BKME-9

“…AbA and its derivatives have recently been evaluated for their ability to function as inhibitors of fungi (5), tumors, mutagenesis, viruses, nitric oxide production (9,12), inflammation (6), and lipoxygenase activity (26). Therefore, enzymes capable of transforming diterpenoids may have potential applications in the synthesis of useful compounds.…”

Crystal Structure of CYP106A2 in Substrate‐Free and Substrate‐Bound Form

“…In this work, it was shown that besides abietic acid ( 1 ), CYP106A2 is also able to convert the resin acids isopimaric acid ( 3 ) and dehydroabietic acid ( 2 ), with the spectroscopic data suggesting that the binding modes of the diterpenoids within the active site are quite different. These compounds are of particular interest because they exhibit a wide variety of biological and pharmaceutical properties, such as antimicrobial, antiviral, and antifungal, as well as antitumoral and antimutagenic activities . Because they are well‐represented in the resin of conifers, they are promising candidates for enzymatically catalyzed functionalization with possible enhancement of their biological activities.…”