The filamentous fungus Colletotrichum fructicola is found in all five continents and is capable of causing severe diseases in a number of economically important plants such as avocado, fig, cocoa, pear, and tea-oil trees. However, almost nothing is known about its patterns of genetic variation and epidemiology on any of its host plant species. Here we analyzed 167 isolates of C. fructicola obtained from the leaves of tea-oil tree Camellia oleifera at 15 plantations in seven Chinese provinces. Multilocus sequence typing was conducted for all isolates based on DNA sequences at fragments of four genes: the internal transcribed spacers of the nuclear ribosomal RNA gene cluster (539 bp), calmodulin (633 bp), glutamine synthetase (711 bp), and glyceraldehyde-3-phosphate dehydrogenase (190 bp), yielding 3.52%, 0.63%, 8.44%, and 7.89% of single nucleotide polymorphic sites and resulting in 15, 5, 12 and 11 alleles respectively at the four gene fragments in the total sample. The combined allelic information from all four loci identified 53 multilocus genotypes with the most frequent represented by 21 isolates distributed in eight tea-oil plantations in three provinces, consistent with long-distance clonal dispersal. However, despite evidence for clonal dispersal, statistically significant genetic differentiation among geographic populations was detected. In addition, while no evidence of recombination was found within any of the four gene fragments, signatures of recombination were found among the four gene fragments in most geographic populations, consistent with sexual mating of this species in nature. Our study provides the first insights into the population genetics and epidemiology of the important plant fungal pathogen C. fructicola.

Endophytes represent a ubiquitous and magical world in plants. Almost all plant species studied by different researchers have been found to harbor one or more endophytes, which protect host plants from pathogen invasion and from adverse environmental conditions. They produce various metabolites that can directly inhibit the growth of pathogens and even promote the growth and development of the host plants. In this review, we focus on the biological control of plant diseases, aiming to elucidate the contribution and key roles of endophytes and their metabolites in this field with the latest research information. Metabolites synthesized by endophytes are part of plant disease management, and the application of endophyte metabolites to induce plant resistance is very promising. Furthermore, multi-omics should be more fully utilized in plant–microbe research, especially in mining novel bioactive metabolites. We believe that the utilization of endophytes and their metabolites for plant disease management is a meaningful and promising research direction that can lead to new breakthroughs in the development of more effective and ecosystem-friendly insecticides and fungicides in modern agriculture.

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Swertia L. is a large genus in the family Gentianaceae. Different chloroplast gene segments have been used to study systematic evolutionary relationships between species of Swertia L. However, as gene fragment–based phylogenies lack sufficient resolution, the systematic evolutionary relationships between Swertia L. species have remained unclear. We sequenced and annotated the complete chloroplast genomes of four Swertia species, namely, S. bifolia, S. tetraptera, S. franchetian, and S. przewalskii, using next generation sequencing and the plastid genome annotator tool. The chloroplast genome sequences of 19 additional species of Swertia L. were downloaded from the NCBI database and also assessed. We found that all 23 Swertia L. species had a similar genetic structure, that is, a ring tetrad structure, but with some clear differences. The chloroplast genomes of the 23 Swertia L. species were 149036–153691 bp long, averaging 152385 bp; the genomes contained 134 functional genes: 38 tRNA, eight rRNA, and 88 protein-encoding genes. A comparative analysis showed that chloroplasts genome of Swertia was conserved in terms of genome structure, codon preference, and repeat sequences, but it differed in terms of genome sizes, gene contents, and SC/IR boundary. Using Swertia wolfangiana as a reference, we found clear divergences in most of the non-coding and intergenic regions of the complete chloroplast genomes of these species; we also found that rpoC1, ccsA, ndhI, ndhA, and rps15 protein-coding genes had large variations. These highly variable hotspots will be useful for future phylogenetic and population genetic studies. Phylogenetic analysis with high bootstrap support showed that Swertia L. was not monophyletic. The classification of subgen. Swertia and subgen. Ophelia was supported by molecular data, which also partly supported the division of sect. Ophelia, sect. Platynema, sect. Poephila, sect. Swertia, and sect. Macranthos. However, the systematic positions of other groups and species require further exploration. The Swertia L formed at 29.60 Ma. Speciation of 10 species occurred in succession after 12 Ma and 13 species occurred in succession after 2.5 Ma. Our analysis provides insight into the unresolved evolutionary relationships of Swertia L. species.

BackgroundTea-oil tree (Camellia oleifera) is a unique edible-oil tree in China, and anthracnose occurs in wherever it is cultivated, causing great economic losses each year. We have previously identified the Ascomycete fungus Colletotrichum fructicola as the major pathogen of anthracnose in Ca. oleifera. The purpose of this study was to characterize the biological function of Snf1 protein, a key component of the AMPK (AMP-activated protein kinase) pathway, for the molecular pathogenic-mechanisms of C. fructicola.ResultsWe characterized CfSnf1 as the homolog of Saccharomyces cerevisiae Snf1. Targeted CfSNF1 gene deletion revealed that CfSnf1 is involved in the utilization of specific carbon sources, conidiation, and stress responses. We further found that the ΔCfSnf1 mutant was not pathogenic to Ca. oleifera, resulting from its defect in appressorium formation. In addition, we provided evidence showing crosstalk between the AMPK and the cAMP/PKA pathways for the first time in filamentous fungi.ConclusionThis study indicate that CfSnf1 is a critical factor in the development and pathogenicity of C. fructicola and, therefore, a potential fungicide target for anthracnose control.