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 Stripe Rust Resistance Genes in Common Wheat Cultivars From the Huang-Huai-Hai Region of China.

Wheat stripe (yellow) rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a serious fungal disease worldwide, especially in the Huang-Huai-Hai region, a main wheat production area in China. Gene postulation, molecular testing, and pedigree analysis were conducted to determine the presence of stripe rust resistance genes to 15 Pst races in 66 selected commercial wheat cultivars released from 2000 to 2016. In addition, races CYR32, CYR33, and CYR34 were used to evaluate resistance to Pst at the adult-plant stage of wheat in the field. Four Yr genes (Yr9, Yr10, Yr26, and Yr32) were postulated in 24 wheat cultivars either singly or in combination. Thirty-six cultivars might contain unknown Yr genes, whereas no identified Yr gene was postulated in six cultivars. Yr9 was detected at a frequency of 28.8%, and no cultivars carried Yr5, Yr15, or Yr18. Ten cultivars (15.2%) exhibited adult-plant resistance in the field tests with three predominant races. Three cultivars (Langyan 43, Xinong 889, and Yunfeng 139) had all-stage resistance. These results are useful to growers selecting cultivars and to breeders aiming to use more resistance genes to develop new cultivars with effective resistance in order to reduce stripe rust damage.

Phenotypic and Genetic Characterization of Botrytis cinerea Population from Kiwifruit in Sichuan Province, China.

Botrytis cinerea (anamorph of Botryotinia fuckeliana) causes gray mold on numerous plants, including kiwifruit. The primary aim of this study was to investigate the phenotypic and genetic characteristics of the Botrytis cinerea population from kiwifruit in Sichuan Province, China. In all, 176 isolates were collected from kiwifruit orchards from eight geographic regions in Sichuan. All isolates were identified as B. cinerea sensu stricto based on the combined datasets, including morphological criteria, determination of the Bc-hch allele, and phylogenetic analysis of the genes RPB2, G3PDH, and HSP60. Three colony types (i.e., sclerotial, mycelial, and conidial) were observed on potato dextrose agar after 2 weeks, with sclerotial isolates, the predominant category, accounting for 40.91%. No obvious differences in microscopic characteristics were observed among the three types. Three genotypes of transposable elements were identified in the B. cinerea population: boty, flipper, and transposa types. The most prevalent genotype from different geographic populations of B. cinerea was transposa; in contrast, the flipper genotype accounted for only 3.98% of the total population, whereas the vacuma genotype was absent. According to MAT locus amplification, 87 and 89 isolates are MAT1-1 and MAT1-2 type, respectively, and the two mating types were found to be balanced overall in the population. Forty-eight representative isolates were all able to cause gray mold to some extent, and disease severities were significantly different between the cultivars Hongyang and Hort16A (P < 0.01). Disease severity was significantly greater on young leaves than on mature leaves (P < 0.01). No significant relationship was found between pathogenicity and geographical region, colony type, or transposon distribution. The results obtained in the present study suggest a relatively uniform species diversity of Botrytis but rich phenotypic and genetic differentiation within the B. cinerea population on kiwifruit in China. Utilizing resistant cultivars and rain-shelter cultivation instead of fungicides may be an effective approach to delaying pathogen variability.