Bioactive Metabolite Production in the Genus Pyrenophora (Pleosporaceae, Pleosporales)

Abstract

The genus Pyrenophora includes two important cereal crop foliar pathogens and a large number of less well-known species, many of which are also grass pathogens. Only a few of these have been examined in terms of secondary metabolite production, yet even these few species have yielded a remarkable array of bioactive metabolites that include compounds produced through each of the major biosynthetic pathways. There is little overlap among species in the compounds identified. Pyrenophora tritici-repentis produces protein toxin effectors that mediate host-specific responses as well as spirocyclic lactams and at least one anthraquinone. Pyrenophora teres produces marasmine amino acid and isoquinoline derivatives involved in pathogenesis on barley as well as nonenolides with antifungal activity, while P. semeniperda produces cytochalasans and sesquiterpenoids implicated in pathogenesis on seeds as well as spirocyclic lactams with phytotoxic and antibacterial activity. Less well-known species have produced some unusual macrocyclic compounds in addition to a diverse array of anthraquinones. For the three best-studied species, in silico genome mining has predicted the existence of biosynthetic pathways for a much larger array of potentially toxic secondary metabolites than has yet been produced in culture. Most compounds identified to date have potentially useful biological activity.

Production of (10S,11S)-(—)-epi-Pyriculol and Its HPLC Quantification in Liquid Cultures of Pyricularia grisea, a Potential Mycoherbicide for the Control of Buffelgrass (Cenchrus ciliaris)

“…Compounds produced by phytopathogenic fungi are of great interest in this context, since they are often related to the development of plant diseases (with specific symptoms such as wilting, suppression of growth, chlorosis, necrosis, or leaf spots), being mostly low-molecular-weight secondary metabolites [ 3 ]. Fungal species belonging to genera such as Botrytis , Pyrenophora , or Pyricularia have been discovered as producers of phytotoxic metabolites with potential use in agriculture [ 1 , 4 , 5 , 6 ]. Specifically, the genus Pyricularia has been a focus of attention.…”

Metabolomic Reconfiguration in Primed Barley (Hordeum vulgare) Plants in Response to Pyrenophora teres f. teres Infection

“…The NBNF disease is a destructive disease of barley that causes important yield losses in susceptible cultivars. Ptt can colonise the host by producing necrotic and chlorotic symptoms due to net blotch in plant tissue [ 5 , 38 , 39 ]. In susceptible barley cultivars, germinated conidia produce the appressorium through the plant membrane at 1 d.p.i.…”

Alternaria alternata Isolated from Infected Pears (Pyrus communis) in Italy Produces Non-Host Toxins and Hydrolytic Enzymes as Infection Mechanisms and Exhibits Competitive Exclusion against Botrytis cinerea in Co-Infected Host Fruits

“…Therefore, the toxic effects of A. alternata metabolites due to NSTs and CWDEs have received minor attention compared to those reported for HSTs mycotoxins [ 10 ]. A wider study of the activity of isolated fungal metabolites can allow the identification of compounds directly related to the pathogenic activity of the fungus, making it possible to create chemo-libraries that facilitate the linking of the structure of the compounds with the species that produce them, and their effect on host and non-host crops, as well as their biosynthetic features [ 11 ]. In this context, we focused on NSTs and CWDEs used by the A. alternata RS strain isolated from infected pears in Italy, and characterization of hydrolytic enzyme activities of A. alternata RS and the identification of the metabolites produced in vitro were undertaken.…”