Polydomus karssenii gen. nov. sp. nov. is a dark septate endophyte with a bifunctional lifestyle parasitising eggs of plant parasitic cyst nematodes (Heterodera spp.)

Abstract

In this study fungal strains were investigated, which had been isolated from eggs of the cereal cyst nematode Heterodera filipjevi, and roots of Microthlaspi perfoliatum (Brassicaceae). The morphology, the interaction with nematodes and plants and the phylogenetic relationships of these strains originating from a broad geographic range covering Western Europe to Asia Minor were studied. Phylogenetic analyses using five genomic loci including ITSrDNA, LSUrDNA, SSUrDNA, rpb2 and tef1-α were carried out. The strains were found to represent a distinct phylogenetic lineage most closely related to Equiseticola and Ophiosphaerella, and Polydomus karssenii (Phaeosphaeriaceae, Pleosporales) is introduced here as a new species representing a monotypic genus. The pathogenicity tests against nematode eggs fulfilled Koch’s postulates using in vitro nematode bioassays and showed that the fungus could parasitise its original nematode host H. filipjevi as well as the sugar beet cyst nematode H. schachtii, and colonise cysts and eggs of its hosts by forming highly melanised moniliform hyphae. Light microscopic observations on fungus-root interactions in an axenic system revealed the capacity of the same fungal strain to colonise the roots of wheat and produce melanised hyphae and microsclerotia-like structure typical for dark septate endophytes. Confocal laser scanning microscopy further demonstrated that the fungus colonised the root cells by predominant intercellular growth of hyphae, and frequent formation of appressorium-like as well as penetration peg-like structures through internal cell walls surrounded by callosic papilla-like structures. Different strains of the new fungus produced a nearly identical set of secondary metabolites with various biological activities including nematicidal effects irrespective of their origin from plants or nematodes.

Omnipolyphilins A and B: Chlorinated Cyclotetrapeptides and Naphtho-α-pyranones from the Plant Nematode-Derived Fungus Polyphilus sieberi

“…For instance, Ijuhya vitellina produces cytotoxic cytochalasans of the chaetoglobosin type and the oligopeptides named leucinostatins with nematicidal activity against Caenorhabditis elegans. , Arthrichitins A and B produced by P. karssenii showed moderate activity against the host cyst nematode Heterodera filipjevi. , The present study deals with the secondary metabolism of two further, hitherto unexplored strains of the recently described species Polyphilus sieberi that were isolated from eggs of the cereal cyst nematode H. filipjevi collected from wheat fields in Turkey .…”

“…6,11 Arthrichitins A and B produced by P. karssenii showed moderate activity against the host cyst nematode Heterodera filipjevi. 8,9 The present study deals with the secondary metabolism of two further, hitherto unexplored strains of the recently described species Polyphilus sieberi that were isolated from eggs of the cereal cyst nematode H. filipjevi collected from wheat fields in Turkey. 12 Herein, we describe the purification and structure elucidation up to the absolute configurations of two previously undescribed chlorinated cyclotetrapeptides (1−2), a new pyranonaphthoquinone (3) and a new dimeric 6,6′-binaphtho-α-pyranone derivative (4) together with nine known metabolites, namely, talaroderxine C (5), 13 gliovirin-like compounds outovirins A (6) and C (7) 14 along with trichodermamide C (8), 15 peniciadametizine B (9), 16 ophiocordylongiiside A (10), 17 two fusidane triterpenes fusidic acid (11), 18,19 3-ketofusidic acid (12), 18,19 and lumichromone (13) 20 from different total extracts of the two nematode eggs-associated strains P. sieberi 17A and 17C.…”

“…Since then, a variety of different fungi associated with plant parasitic nematodes were found . They include but are not limited to the following: Ijuhya vitellina, Niesslia gamsii, Polydomus karssenii, , and Pochonia chlamydosporia . Studies of the secondary metabolites of these fungi showed that they can be prolific producers of biologically active secondary metabolites.…”

Laburnicotides A–F: Acyclic N-Acetyl Oligopeptides from the Nematode-Cyst-Associated Fungus Laburnicola nematophila

“…The nematode parasitic fungus L. nematophila and other recently reported fungi Polyphilus sieberi and Polydomus karssenii have been studied for their production of secondary metabolites, positioning these nematode-associated fungi as a compelling subject for investigation. − Herein, we report the chemical and biological characterization of six undescribed acyclic N -acetyl oligopeptides ( 1 – 6 ) from two different strains of L. nematophila (20AD and K01).…”

Exploring the Diversity and Systematics of Phaeosphaeriaceae: Taxonomic Novelties from Ecologically Diverse Habitats and Their Phylogenetic Resolution

“…Since Phaeosphaeriaceae are cosmopolitan and ecologically important, studying their ecological relationships is essential to understand them in a broader sense [ 1 , 4 ]. In addition, some genera (i.e., Polydomus and Setophoma ) have significant practical applications, including as sources of biological activities and biotechnological products [ 6 , 7 , 8 ]. Therefore, conducting research on Phaeosphaeriaceae is an important step towards unlocking their potential applications.…”