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Carvacrol expresses a wide range of biological activities, but the studies of its mechanisms focused on bacteria, mainly involving the destruction of the plasma membrane. In this study, carvacrol exhibited strong activities against several phytopathogenic fungi and demonstrated a novel antifungal mechanism against Lasiodiplodia theobromae. RNA sequencing indicated that many genes of L. theobromae hyphae were predominately induced by carvacrol, particularly those involved in replication and transcription. Hyperchromic, hypsochromic, and bathochromic effects in the UV-visible absorption spectrum were observed following titration of calf thymus DNA (ctDNA) and carvacrol, which indicated the formation of a DNA–carvacrol complex. Circular dichroism (CD) spectroscopy indicated that the response of DNA to carvacrol was similar to that of 4′,6-diamidino-2-phenylindole (DAPI) but different from that of ethidium bromide (EB), implying the ionic bonds between carvacrol and ctDNA. Fluorescence spectrum (FS) analysis indicated that carvacrol quenched the fluorescence of double-stranded DNA (dsDNA) more than single-stranded DNA, indicating that carvacrol mainly bound to dsDNA. A displacement assay showed that carvacrol reduced the fluorescence intensity of the DNA–DAPI complex through competition with DAPI, but this did not occur for DNA–EB. The FS assay revealed that carvacrol bound to the AAA sequence on the minor groove of ds-oligonucleotides. The hydroxyl of carvacrol was verified to bind to ctDNA through a comparative test in which structural analogs of carvacrol, including thymol and 4-ethyl-1,2-dimethyl, were analyzed. The current study indicated carvacrol can destruct plasma membranes and bind to the minor groove of DNA, inhibiting fungal proliferation by disturbing the stability of dsDNA. [ABSTRACT FROM AUTHOR]

Because effective control measures are lacking, tea leaf spot caused by Didymella segeticola results in huge tea (Camellia sinensis) production losses on tea plantations in Guizhou Province, southwestern China. Screening for natural antimicrobial agents with higher control effects against this pathogen and studying their modes of action may contribute to disease management. Here, Penicillium griseofulvum-derived antimicrobial griseofulvin (GSF) can inhibit the hyphal growth of D. segeticola strain GZSQ-4, with a half-maximal effective concentration of 0.37 μg/ml in vitro and a higher curative efficacy at a lower dose of 25 μg/ml for detached tea twigs. GSF induces deformed and slightly curly hyphae with enlarged ends, with protoplasts agglutinated in the hyphae, and higher numbers of hyphal protuberances. GSF alters hyphal morphology and the subcellular structure's order. The integrated transcriptome and proteome data revealed that the transport of materials in cells, cellular movement, and mitosis were modulated by GSF. Molecular docking indicated that beta-tubulin was the most potent target of GSF, with a binding free energy of −13.59 kcal/mol, and microscale thermophoresis indicated that the dissociation constant (Kd) value of GSF binding to beta-tubulin 1, compared with beta-tubulin 2, was significantly lower. Thus, GSF potentially targets beta-tubulin 1 to disturb the chromosomal separation and fungal mitosis, thereby inhibiting hyphal growth. [ABSTRACT FROM AUTHOR]

Because of the lack of effective disease management measures, tea leaf differenspot-caused by the fungal phytopathogen Didymella segeticola (syn Phoma segeticola)-is an important foliar disease. The important and metabwidely used agricultural antimicrobial kasugamycin (Ksg), produced by reducthe Gram-Positive bacterium Streptomy, <:s kastigaensis, effects high levels control against crop diseases. The results of this study indicated that Ksg could inhibit the growth of D. segencola hyphae in vitro with a half-maximal effec-segetitive concentration *C-O) of 141.18 pg ml-' Meanwhile. the curative effect in vivo on the pathogen in detached tea leaves also demonstrated that Ksg induced some moiphological changes iii organelles, septa, and cell walls observed by optical mici'Oscopy and by scanning and transmission electron microscopy. This may indicate that Ksg disturbs biosynthesis of key metabo-lites. inhibiting hyphal growth. Integrated transcriptomic. proteomic. and bioinformatic analyses revealed that differentially expressed genes or differenspottially expressed proteins in D, segeticola hyphae in response to Ksg exposure were involved with metabolic processes and biosynthesis of secondary metabwidely olites. Molecular docking studies indicated that Ksg may target nitrate reducthe tase (NR). and microscale thermophoresis assay showed greater affinity with NR. potentially disturbing nitrogen assimilation and subsequent metabolism. The results indicated that Ksg inhibits the pathogen of tea leaf spot, D. segetitive rola. possibly by binding to NR, disturbing fungal metabolism, and inducing subsequent changes in hyphal growth and development. [ABSTRACT FROM AUTHOR]

Tea leaf spot, caused by Lasiodiplodia theobromae, is an important disease that can seriously decrease the production and quality of tea (Camellia sinensis (L.) O. Kuntze) leaves. The analysis of circular RNA (circRNA) in tea leaves after infection by the pathogen could improve understanding about the mechanism of host-pathogen interactions. In this study, high-performance sequencing of circRNA from C. sinensis Fuding-dabaicha leaves that had been infected with L. theobromae was conducted using the Illumina HiSeq 4000 platform. In total, 192 and 153 differentially expressed circRNAs from tea leaves were significantly up- and downregulated, respectively, after infection with L. theobromae. A gene ontology analysis indicated that the differentially expressed circRNA-hosting genes for DNA binding were significantly enriched. The genes with significantly differential expressions that were annotated in the specified database (S genes) were σ factor E isoform 1, triacylglycerol lipase SDP1, DNA-directed RNA polymerase III subunit 2, WRKY transcription factor WRKY24, and regulator of nonsense transcripts 1 homolog. A Kyoto Encyclopedia of Genes and Genomes analysis indicated that the significantly enriched circRNA-hosting genes involved in the plant-pathogen interaction pathway were Calmodulin-domain protein kinase 5 isoform 1, probable WRKY transcription factor 33, U-box domain-containing protein 35, probable inactive receptor-like protein kinase At3g56050, WRKY transcription factor WRKY24, mitogen-activated protein kinase kinase kinase YODA, SGT1, and protein DGS1. Functional annotation of circRNAs in tea leaves infected by L. theobromae will provide a valuable resource for future research on host-pathogen interactions. [ABSTRACT FROM AUTHOR]

Tea leaf spot, caused by the fungal phytopathogen Didymella segeticola, is an important foliar disease that can cause huge losses in the production and quality of tea, and there are no effective management measures to control the disease. This study screened a natural antimicrobial chemical for its activity against D. segeticola and studied its mode of action. Antifungal activity of the Streptomyces-derived antimicrobial zhongshengmycin (ZSM) against D. segeticola strain GZSQ-4 was assayed in vitro via the mycelial growth rate method. Optical microscopy and scanning and transmission electron microscopy were used to observe the morphological effects on hyphae treated with ZSM, with these studies complemented by transcriptomic, proteomic, and bioinformatic studies to identify the differentially expressed genes or differentially expressed proteins in hyphae treated with ZSM. Correlation analysis of transcriptomic and proteomic data were used to reveal the mode of action. The results indicated that ZSM could inhibit the growth of hyphae in vitro with a half-maximal effective concentration of 5.9 lg/ml, inducing some morphological changes in organelles, septa, and extracellular polysaccharides, targeting ribosomes to disturb translation, affecting the biosynthesis of some hyphal proteins at the messenger RNA and protein levels, and revealing correlations between findings from transcriptomes and proteomes. [ABSTRACT FROM AUTHOR]

Lasiodiplodia theobromae is a phytopathogenic fungus, which can cause many different diseases on different crops. The pathogen can cause leaf spot on tea plants (Camellia sinensis), which negatively affects the productivity and quality of tea leaves in tea plantations in Guizhou Province, China. Although the genome sequence of L. theobromae has been published, no data on the transcriptome or small RNA sequences of L. theobromae under in vitro conditions and the course of infection of tea leaf are available. Here, we report the high-quality transcriptome and small RNA sequences of L. theobromae in vitro conditions and the course of infection of tea leaf using the platform of Illumina HiSeq. This comprehensive expression profiling of the fungal pathogen will provide a valuable resource for future research on trait-specific genes of the pathogen, host-pathogen interactions, and disease resistance in the host. [ABSTRACT FROM AUTHOR]

The fungal pathogen Didymella segeticola (basionym Phoma segeticola) causes leaf spot on tea (Camellia sinensis), which leads to a loss in tea leaf production in Guizhou Province, China. D. segeticola isolate GZSQ-4 was sequenced using lllumina HiSeq and Pacific Biosciences (PacBio) RS technologies, and then assembled to approximately 33.4 Mbp with a scaffold N50 value of approximately 2.3 Mbp. In total, 10,893 genes were predicted using the Nonredundant, Gene Ontology, Clusters of Orthologous Groups, Kyoto Encyclopedia of Genes and Genomes, and SWISS-PROT databases. The whole-genome sequence of D. segeticola will provide a resource for future research on host-pathogen interactions, determination of trait-specific genes, pathogen evolution, and plant-host adaptation mechanisms. [ABSTRACT FROM AUTHOR]