Anthracnose Disease of Carpetgrass (Axonopus compressus) Caused by Colletotrichum hainanense sp. nov

Colletotrichum siamense, a Novel Causal Agent of Viburnum odoratissimum Leaf Blotch and Its Sensitivity to Fungicides

Viburnum odoratissimum Ker-Gawl is native to Asia and is usually used as a garden ornamental. In September 2022, a leaf blotch on V. odoratissimum was observed in Nanjing, Jiangsu, China. The disease causes the leaves of the plants to curl and dry up and defoliate early. It not only seriously affects the growth of the plants but also greatly reduces the ornamental value. The pathogenic fungus was isolated from the diseased leaves, and the fungus was identified to be Colletotrichum siamense based on morphological features and multilocus phylogenetic analyses of the internal transcribed spacer (ITS) region, actin (ACT), calmodulin (CAL), beta-tubulin 2 (TUB2), chitin synthase (CHS-1), Apn2-Mat1-2 intergenic spacer and partial mating type (ApMat), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes. Pathogenicity tests were performed by inoculating healthy leaves with conidia. C. siamense can grow at 15-35 °C, with an optimal growth temperature at 25-30 °C. The results of sensitivity to nine fungicides showed that C. siamense was the most sensitive to prochloraz in the concentration range of 0.01 μg/mL to 100 μg/mL. Therefore, spraying prochloraz before the optimum growth temperature of pathogenic fungus can achieve effective control. It provided useful information for future studies on the prevention and treatment strategies of C. siamense. This is the first report of leaf blotch caused by C. siamense on V. odoratissimum in China and worldwide.

Two Newly Identified Colletotrichum Species Associated with Mango Anthracnose in Central Thailand

Anthracnose caused by Colletotrichum spp. is one of the major problems in mango production worldwide, including Thailand. All mango cultivars are susceptible, but Nam Dok Mai See Thong (NDMST) is the most vulnerable. Through a single spore isolation method, a total of 37 isolates of Colletotrichum spp. were obtained from NDMST showing anthracnose symptoms. Identification was performed using a combination of morphology characteristics, Koch's postulates, and phylogenetic analysis. The pathogenicity assay and Koch's postulates on leaves and fruit confirmed that all Colletotrichum spp. tested were causal agents of mango anthracnose. Multilocus analysis using DNA sequences of internal transcribed spacer (ITS) regions, β-tubulin (TUB2), actin (ACT), and chitin synthase (CHS-1) was performed for molecular identification. Two concatenated phylogenetic trees were constructed using either two-loci of ITS and TUB2, or four-loci of ITS, TUB2, ACT, and CHS-1. Both phylogenetic trees were indistinguishable and showed that these 37 isolates belong to C. acutatum, C. asianum, C. gloeosporioides, and C. siamense. Our results indicated that using at least two loci of ITS and TUB2, were sufficient to infer Colletotrichum species complexes. Of 37 isolates, C. gloeosporioides was the most dominant species (19 isolates), followed by C. asianum (10 isolates), C. acutatum (5 isolates), and C. siamense (3 isolates). In Thailand, C. gloeosporioides and C. acutatum have been reported to cause anthracnose in mango, however, this is the first report of C. asianum and C. siamense associated with mango anthracnose in central Thailand.

Discovery, Genomic Sequence Characterization and Phylogenetic Analysis of Novel RNA Viruses in the Turfgrass Pathogenic Colletotrichum spp. in Japan

Turfgrass used in various areas of the golf course has been found to present anthracnose disease, which is caused by Colletotrichum spp. To obtain potential biological agents, we identified four novel RNA viruses and obtained full-length viral genomes from turfgrass pathogenic Colletotrichum spp. in Japan. We characterized two novel dsRNA partitiviruses: Colletotrichum associated partitivirus 1 (CaPV1) and Colletotrichum associated partitivirus 2 (CaPV2), as well as two negative single-stranded (ss) RNA viruses: Colletotrichum associated negative-stranded RNA virus 1 (CaNSRV1) and Colletotrichum associated negative-stranded RNA virus 2 (CaNSRV2). Using specific RT-PCR assays, we confirmed the presence of CaPV1, CaPV2 and CaNSRV1 in dsRNAs from original and sub-isolates of Colletotrichum sp. MBCT-264, as well as CaNSRV2 in dsRNAs from original and sub-isolates of Colletotrichum sp. MBCT-288. This is the first time mycoviruses have been discovered in turfgrass pathogenic Colletotrichum spp. in Japan. CaPV1 and CaPV2 are new members of the newly proposed genus "Zetapartitivirus" and genus Alphapartitivirus, respectively, in the family Partitiviridae, according to genomic characterization and phylogenetic analysis. Negative sense ssRNA viruses CaNSRV1 and CaNSRV2, on the other hand, are new members of the family Phenuiviridae and the proposed family "Mycoaspirividae", respectively. These findings reveal previously unknown RNA virus diversity and evolution in turfgrass pathogenic Colletotrichum spp.

Colletotrichum litangense sp. nov., Isolated as an Endophyte of Hippuris vulgaris, an Aquatic Plant in Sichuan, China

An unknown endophytic fungus was isolated from the aquatic plant Hippuris vulgaris in Litang county, Sichuan province, China. Phylogenetic analyses inferred from combined ITS, Sod2, Apn2, and TUB2 sequences revealed that the endophyte is a new species belonging to the Colletotrichum graminicola species complex. Morphological characteristics showed that Colletotrichum litangense is characterized by its falcate, lunate to sublunate conidia, and ellipsoidal, ovoid, or lobed appressoria. Pathogenicity tests on several fruits showed that C. litangense could induce anthracnose lesions. As a result of the phylogenetic, morphological, and pathogenicity analyses, we proposed the name Colletotrichum litangense for the new species.

New species of Colletotrichum from wild Poaceae and Cyperaceae plants in Iran

Twenty-two Colletotrichum strains were isolated from anthracnose symptoms or leaf spots on leaves of various wild Poaceae and Cyperaceae plants collected in three provinces of Iran and tentatively identified as belonging to the Graminicola species complex based on morphology. All strains were studied via a polyphasic approach combining colony characteristics, morphology and phylogeny inferred from multi-locus sequences, including the nuc rDNA ITS1-5.8S-ITS2 (ITS), partial sequences of the β-tubulin (tub2), actin (act), manganese superoxide dismutase 2 (sod2), DNA lyase 2 (apn2) genes, a 200-bp intron of the glyceraldehyde-3-phosphate dehydrogenase (gapdh), and the intergenic spacer between the apn2 gene and the mat1 idiomorph (apn2/mat1). Six species were distinguished, including three new species, namely C. caspicum, C. persicum, and C. sacchari, and three previously described species, C. cereale, C. nicholsonii and C. sublineola. Comprehensive morphological descriptions and illustrations are provided for all species. Furthermore, this study provided new insights into the distribution and host range of known species.