Diversity of Trichoderma species associated with soil in the Zoige alpine wetland of Southwest China.

The ecology of soil fungi is poorly understood, and recent comprehensive reports on Trichoderma are unavailable for any region, including the Zoige alpine wetland ecological region in China. One hundred soil samples were collected from different soil types and soil layers in Zoige alpine wetland ecological regions. Using the traditional suspension plating method, 80 Trichoderma strains were chosen to analyze species diversity. After a preliminary classification of morphological characteristics and the genes glyceraldehyde-3-phosphate dehydrogenase (gpd), 57 representative strains were selected and eventually identified as seven species via phylogenetic analyses of multilocus sequences based on the genes transcription elongation factor 1 alpha (tef1), encoding RNA polymerase II subunit B (rpb2) and ATP citrate lyase (acl1). Among them, T. harzianum was the dominant species isolated from five soil layers and four soil types, and had the highest isolation frequency (23%) in this zone, while T. polysporum and T. pyramidale were rare species, with isolation frequencies of less than 1%. Our detailed morphological observation and molecular phylogenetic analyses support the recognition of Trichoderma zoigense was described for the first time as a new species, while T. atrobrunneum as a new record for China was found. Our results will be used as a reference for a greater understanding of soil microbial resources, ecological rehabilitation and reconstructions in the Zoige alpine wetland.

Identification of Colletotrichum Species Associated with Anthracnose Disease of Strawberry in Sichuan Province, China.

Strawberry anthracnose, caused by Colletotrichum species, is a major fungal disease threatening the strawberry industry in Sichuan Province of southwestern China. However, research on identification of Colletotrichum species associated with strawberry anthracnose in Sichuan remains scarce. In this study, 73 representative Colletotrichum strains were isolated from diseased leaves, stolons, petioles, and crowns of 11 major strawberry-planting localities in Sichuan Province. Based on morphological characteristics and multiloci phylogenetic analysis, the Colletotrichum strains were identified as three distinct species: Colletotrichum fructicola (53 strains, 72.60%), Colletotrichum siamense (17 strains, 23.29%), and Colletotrichum gloeosporioides sensu stricto (3 strains, 4.11%). Among them, C. fructicola was the most ubiquitous and dominant species, whereas C. gloeosporioides sensu stricto was restricted to Chongzhou. Importantly, our pathogenicity tests showed that C. fructicola and C. siamense can infect both leaves and stolons, whereas C. gloeosporioides sensu stricto was only pathogenic to leaves. Interestingly, although the sexual stage of C. siamense was not observed in this study, it still exhibited the strongest virulence to strawberry compared with C. gloeosporioides sensu stricto and C. fructicola. This is the first study to characterize Colletotrichum species causing strawberry anthracnose and evaluate their pathogenicity in Sichuan Province of southwestern China, which will provide a better strategy for accurate diagnosis and management of anthracnose disease in strawberry.

Molecular and phenotypic characterization of Colletotrichum species associated with anthracnose disease in peppers from Sichuan Province, China.

The anthracnose caused by Colletotrichum species is an important disease that primarily causes fruit rot in pepper. Eighty-eight strains representing seven species of Colletotrichum were obtained from rotten pepper fruits in Sichuan Province, China, and characterized according to morphology and the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) sequence. Fifty-two strains were chosen for identification by phylogenetic analyses of multi-locus sequences, including the nuclear ribosomal internal transcribed spacer (ITS) region and the ß-tubulin (TUB2), actin (ACT), calmodulin (CAL) and GAPDH genes. Based on the combined datasets, the 88 strains were identified as Colletotrichum gloeosporioides, C. siamense, C. fructicola, C. truncatum, C. scovillei, and C. brevisporum, and one new species was detected, described as Colletotrichum sichuanensis. Notably, C. siamense and C. scovillei were recorded for the first time as the causes of anthracnose in peppers in China. In addition, with the exception of C. truncatum, this is the first report of all of the other Colletotrichum species studied in pepper from Sichuan. The fungal species were all non-host-specific, as the isolates were able to infect not only Capsicum spp. but also Pyrus pyrifolia in pathogenicity tests. These findings suggest that the fungal species associated with anthracnose in pepper may inoculate other hosts as initial inoculum.