Cyst nematodes are globally important pathogens in agriculture. Their sedentary lifestyle and long-term association with the roots of host plants render cyst nematodes especially good targets for attack by parasitic fungi. In this context fungi were specifically isolated from nematode eggs of the cereal cyst nematode Heterodera filipjevi. Here, Ijuhya vitellina (Ascomycota, Hypocreales, Bionectriaceae), encountered in wheat fields in Turkey, is newly described on the basis of phylogenetic analyses, morphological characters and life-style related inferences. The species destructively parasitises eggs inside cysts of H. filipjevi. The parasitism was reproduced in in vitro studies. Infected eggs were found to harbour microsclerotia produced by I. vitellina that resemble long-term survival structures also known from other ascomycetes. Microsclerotia were also formed by this species in pure cultures obtained from both, solitarily isolated infected eggs obtained from fields and artificially infected eggs. Hyphae penetrating the eggshell colonised the interior of eggs and became transformed into multicellular, chlamydospore-like structures that developed into microsclerotia. When isolated on artificial media, microsclerotia germinated to produce multiple emerging hyphae. The specific nature of morphological structures produced by I. vitellina inside nematode eggs is interpreted as a unique mode of interaction allowing long-term survival of the fungus inside nematode cysts that are known to survive periods of drought or other harsh environmental conditions. Generic classification of the new species is based on molecular phylogenetic inferences using five different gene regions. I. vitellina is the only species of the genus known to parasitise nematodes and produce microsclerotia. Metabolomic analyses revealed that within the Ijuhya species studied here, only I. vitellina produces chaetoglobosin A and its derivate 19-O-acetylchaetoglobosin A. Nematicidal and nematode-inhibiting activities of these compounds have been demonstrated suggesting that the production of these compounds may represent an adaptation to nematode parasitism.
Hibiscus rosa-sinensis L. (Hibiscus, Malvaceae) is an ornamental species grown widely in amenity plantings. We collected leaves on an urban roadside pavement (sidewalk) near a market in Guangzhou which showed multiple symptoms of leaf rolling, deformation and chlorosis. Initial evaluation by electron microscopy using negative staining of drip preparations revealed the presence of tobamovirus-like particles. Total RNA was extracted, and, unusually, without any RNA selection based on sequence, was used for cDNA library construction and high-throughput survey sequencing. From the 814 Mb of clean sequence data (from 2,712,161 paired reads of 150 bp) reads representing chloroplast, ribosomal, and mitochondrial genes were filtered out, eliminating 79.1% of reads. 1,135,848 x 150 bp of the sequence was retained and screened for viral sequences. Assembly of these sequences detected nine virus species from seven virus genera comprising three tobamoviruses, namely, Tobacco mosaic virus, Tobacco mild green mosaic virus and Hibiscus latent Singapore virus, Turnip mosaic virus (Potyvirus), Potato virus M (Carlavirus), Hibiscus chlorotic ringspot virus (Betacarmovirus), Fabavirus sp (Fabavirus), Cotton leaf curl Multan virus (Begomovirus) and a putative mitoviruses replicating in mitochondria, Chenopodium quinoa mitovirus 1. Mapping the reads to complete virus reference sequences showed high and uniform coverage of the genomes from 3,729x coverage for Turnip mosaic virus to 22x for Cotton leaf curl Multan virus. By comparison, nuclear reference genes actin showed 14x coverage and polyubiquitin 27x. Notable variants from reference sequences (SNPs) were identified. With the low cost of sequencing and potential for semi-automated bioinformatic pipelines, the whole-RNA approach has huge potential for identifying multiple undiagnosed viruses in ornamental plants, resulting in the ability to take preventive measures in production facilities against spread and to product quality for the mutual benefit of producers and consumers.
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