Lipoperoxidation affects ochratoxin A biosynthesis in Aspergillus ochraceus and its interaction with wheat seeds

Abstract

In Aspergillus nidulans, Aspergillus flavus, and Aspergillus parasiticus, lipoperoxidative signalling is crucial for the regulation of mycotoxin biosynthesis, conidiogenesis, and sclerotia formation. Resveratrol, which is a lipoxygenase (LOX) and cyclooxygenase inhibitor, downmodulates the biosynthesis of ochratoxin A (OTA) in Aspergillus ochraceus. In the genome of A. ochraceus, a lox-like sequence (AoloxA; National Center for Biotechnology Information (NCBI) accession number: DQ087531) for a lipoxygenase-like enzyme has been found, which presents high homology (100 identities, 100 positives %, score 555) with a lox gene of Aspergillus fumigatus (NCBI accession number: XM741370). To study how inhibition of oxylipins formation may affect the A. ochraceus metabolism, we have used a DeltaAoloxA strain. This mutant displays a different colony morphology, a delayed conidia formation, and a high sclerotia production. When compared to the wild type, the DeltaAoloxA strain showed a lower basal activity of LOX and diminished levels of 13-hydroperoxylinoleic acid (HPODE) and other oxylipins derived from linoleic acid. The limited oxylipins formation corresponded to a remarkable inhibition of OTA biosynthesis in the DeltaAoloxA strain. Also, wheat seeds (Triticum durum cv Ciccio) inoculated with the DeltaAoloxA mutant did not accumulate 9-HPODE, which is a crucial element in the host defence system. Similarly, the expression of the pathogenesis-related protein 1 (PR1) gene in wheat seeds was not enhanced. The results obtained contribute to the current knowledge on the role of lipid peroxidation governed by the AoloxA gene in the morphogenesis, OTA biosynthesis, and in host-pathogen interaction between wheat seeds and A. ochraceus.

Physiological and antioxidant response by Beauveria bassiana Bals (Vuill.) to different oxygen concentrations

“…Similarly, studies have been carried out on different species of Aspergillus linking toxin production and the presence of oxidized lipids (Passi et al 1984;Reverberi et al 2010). Additionally, Cortés-Rojo et al (2009) found damage to the respiratory chain in S. cerevisiae with mitochondria sensitive to lipoperoxidation.…”

A Caleosin-Like Protein with Peroxygenase Activity Mediates Aspergillus flavus Development, Aflatoxin Accumulation, and Seed Infection

“…A lipoxygenase-like enzyme-deficient Aspergillus ochraceus strain producing low levels of linoleic acid-derived 13-hydroperoxyoctadecadienoic acid (13-HPOD) displayed decreased ochratoxin A production and delayed formation of conidia but increased production of sclerotia. Complementation of the culture medium with 9-HPOD and 13-HPOD enhanced the production of ochratoxin A in wild-type (WT) A. ochraceus but not in a mutant in which the LOX-like gene was deleted (19). Fungal production of aflatoxins seems to be favored by an oxidative environment.…”

“…Whereas in plants such enzymes form essentially three types of hydroperoxides (OOHs), i.e., 9-OOH, 13-OOH, and 2-OOH, in fungi, they can introduce molecular oxygen on the carbon 8, 10, 11, or 15 of PUFA, yielding 8-OOH, 10-OOH, 11-OOH, and 15-OOH derivatives, respectively (8,10,11,17,18). Whatever their mode of formation, fatty acid hydroperoxides (FAOOHs) and their metabolites have been reported to play crucial roles in the life cycle of fungi, notably, in conidiogenesis and sclerotium formation (19). In addition, Ppo-derived psi factors produced by Aspergillus nidulans were shown to regulate both asexual and sexual spore development (12,14,20).…”

Quantitative profiling of oxylipins through comprehensive LC-MS/MS analysis ofFusarium verticillioidesand maize kernels

“…As free FAs, linoleic acid levels partly regulate development, seed colonisation and mycotoxin production by Aspergillus spp. (Calvo et al 1999;Horowitz Brown et al 2008;Brown et al 2009;Reverberi et al 2010;Nobili et al 2014;Scarpari et al 2014). …”