Calm Before the Storm: A Glimpse into the Secondary Metabolism of Aspergillus welwitschiae, the Etiologic Agent of the Sisal Bole Rot

Abstract

Aspergillus welwitschiae is a species of the Nigri section of the genus Aspergillus. In nature, it is usually a saprotroph, decomposing plant material. However, it causes the bole rot disease of Agave sisalana (sisal), a plant species used for the extraction of hard natural fibers, causing great economic loss to this culture. In this study, we isolated and sequenced one genome of A. welwitschiae (isolate CCMB 674 (Collection of Cultures of Microorganisms of Bahia)) from the stem tissues of sisal and performed in silico and wet lab experimental strategies to describe its ability to produce mycotoxins. CCMB 674 possesses 64 secondary metabolite gene clusters (SMGCs) and, under normal conditions, it produces secondary metabolism compounds that could disturb the cellular cycle of sisal or induce abnormalities in plant growth, such as malformin C. This isolate also produces a pigment that might explain the characteristic red color of the affected tissues. Additionally, this isolate is defective for the production of fumonisin B1, and, despite bearing the full cluster for the synthesis of this compound, it did not produce ochratoxin A. Altogether, these results provide new information on possible strategies used by the fungi during the sisal bole rot, helping to better understand this disease and how to control it.

Research Progress on Phytopathogenic Fungi and Their Role as Biocontrol Agents

“…In the long evolutionary history of plants and pathogenic fungi, highly specialized and extremely complex relationships have formed, creating a pattern of mutual selection and co-evolution. Therefore, with the continuous emergence of new varieties and variations of pathogenic fungi, their relationships with plants have also changed (Quintanilha-Peixoto et al, 2019). Based on agricultural production practices and by combining genetic variation and antifungal disease breeding using biochemical, cell biology, and molecular biology methods, a comprehensive analysis of the mechanism of the interaction between pathogenic fungi and host plants is required.…”

Antibacterial Effect and Mode of Action of Secondary Metabolites from Fungal Endophyte Associated with Aloe ferox Mill

“…The results implied that the extract had only a bacteriostatic effect [48]. In a previous study, secondary metabolites from A. welwitschiae were also reported to demonstrate significant antimicrobial activity [37]. The profound antibacterial activity observed in this study suggests that A. welwitschiae MH545928.1 might be playing a vital role in the protection of A. ferox Mill against pathogens.…”

“…A. welwitschiae is a filamentous fungus that belongs to the Nigri group of the genus Aspergillus. It is a saprotroph known to decompose plant material [37]. It has been reported to produce secondary metabolites with antibacterial [38] and anti-virulence activities [39] and is used as biocontrol [40].…”

The Sisal Virome: Uncovering the Viral Diversity of Agave Varieties Reveals New and Organ-Specific Viruses

“…The mycoviruses sharing similarities with our species are Agaricus bisporus virus 5 and Agaricus bisporus virus 6 [ 64 ], Alternaria alternata virus 1 [ 65 ], Aspergillus foetidus dsRNA mycovirus [ 66 ], Aspergillus heteromorphus alternavirus 1 [ 67 ], Podosphaera prunicola tobamo-like virus [ 68 ], Macrophomina phaseolina tobamo-like virus [ 69 ], Botryosphaeria dothidea tobamo-like virus (unpublished) , and Stemphylium lycopersici mycovirus (unpublished) ( Table 1 ). The occurrence of viral species showing similarity with Aspergillus mycoviruses, and their pattern of expression (higher in stems and roots, but also present in leaves) leads us to hypothesize that Aspergillus welwitschiae , a fungal species which causes the bole rot of sisal [ 70 , 71 ] is also part of the healthy microbiome of sisal, causing disease through imbalances in plant metabolism, rather than infecting vulnerable plants from spores in the environment. Such a pattern has been described in peppermint by Dakin et al (2010) [ 72 ].…”