Dataset Information

Species Diversity, Mating Strategy and Pathogenicity of Calonectria Species from Diseased Leaves and Soils in the Eucalyptus Plantation in Southern China.

ABSTRACT: Many Calonectria species are causal agents of diseases on several forestry, agricultural and horticultural crops. Calonectria leaf blight is one of the most important diseases associated with Eucalyptus plantations and nurseries in Asia and South America. Recently, symptoms of leaf rot and leaf blight caused by Calonectria species were observed in a one-year-old Eucalyptus experimental plantation in GuangXi Province, southern China. To better understand the species diversity, mating strategy and pathogenicity of Calonectria species isolated from diseased tissues and soils, diseased leaves and soils under the trees from ten Eucalyptus urophylla hybrid genotypes were collected. Three hundred and sixty-eight Calonectria isolates were obtained from diseased Eucalyptus leaves and soils under these trees, and 245 representative isolates were selected based on the sampling substrates and Eucalyptus genotypes and identified by DNA sequence analyses based on the translation elongation factor 1-alpha (tef1), ?-tubulin (tub2), calmodulin (cmdA) and histone H3 (his3) gene regions, as well as a combination of morphological characteristics. These isolates were identified as Calonectria hongkongensis (50.2%), C. pseudoreteaudii (47.4%), C. aconidialis (1.6%), C. reteaudii (0.4%) and C. auriculiformis (0.4%). This is the first report of C. reteaudii and C. auriculiformis occurrence in China. Calonectria pseudoreteaudii was isolated from both Eucalyptus diseased leaves and soils; the other four species were only obtained from soils. MAT1-1-1 and MAT1-2-1 gene amplification and mating type assignment results showed that C. pseudoreteaudii is heterothallic and an asexual cycle represents the primary reproductive mode, C. reteaudii and C. auriculiformis are likely to be heterothallic and C. hongkongensis and C. aconidialis are homothallic. Based on the genetic diversity comparisons for C. pseudoreteaudii isolates from diseased leaves and soils, we hypothesize that C. pseudoreteaudii in soils was spread from diseased leaves. Both the mycelia plug and conidia suspension inoculations indicated that all five Calonectria species were pathogenic to the two Eucalyptus genotypes tested and the tolerance of the two genotypes differed. It is necessary to understand the ecological niche and epidemiological characteristics of these Calonectria species and to select disease resistant Eucalyptus genotypes in southern China in the future.

SUBMITTER: Wu W

PROVIDER: S-EPMC7909555 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature

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Species Diversity, Mating Strategy and Pathogenicity of Calonectria Species from Diseased Leaves and Soils in the Eucalyptus Plantation in Southern China.

Wu WenXia W Chen ShuaiFei S

Journal of fungi (Basel, Switzerland) 20210120 2

Many Calonectria species are causal agents of diseases on several forestry, agricultural and horticultural crops. Calonectria leaf blight is one of the most important diseases associated with Eucalyptus plantations and nurseries in Asia and South America. Recently, symptoms of leaf rot and leaf blight caused by Calonectria species were observed in a one-year-old Eucalyptus experimental plantation in GuangXi Province, southern China. To better understand the spe ...[more]

PMID: 33498546

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Project description:The genus Calonectria includes pathogens of various agricultural, horticultural, and forestry crops. Species of Calonectria are commonly collected from soils, fruits, leaves, stems, and roots. Some species of Calonectria isolated from soils are considered as important plant pathogens. Understanding the species diversity and distribution characteristics of Calonectria species in different soil layers will help us to clarify their long-term potential harm to plants and their patterns of dissemination. To our knowledge, no systematic research has been conducted concerning the species diversity and distribution characteristics of Calonectria in different soil layers. In this study, 1000 soil samples were collected from five soil layers (0-20, 20-40, 40-60, 60-80, and 80-100 cm) at 100 sampling points in one 15-year-old Eucalyptus urophylla hybrid plantation in southern China. A total of 1037 isolates of Calonectria present in all five soil layers were obtained from 93 of 100 sampling points. The 1037 isolates were identified based on DNA sequence comparisons of the translation elongation factor 1-alpha (tef1), β-tubulin (tub2), calmodulin (cmdA), and histone H3 (his3) gene regions, as well as the combination of morphological characteristics. These isolates were identified as C. hongkongensis (665 isolates; 64.1%), C. aconidialis (250 isolates; 24.1%), C. kyotensis (58 isolates; 5.6%), C. ilicicola (47 isolates; 4.5%), C. chinensis (2 isolates; 0.2%), and C. orientalis (15 isolates; 1.5%). With the exception of C. orientalis, which resides in the C. brassicae species complex, the other five species belonged to the C. kyotensis species complex. The results showed that the number of sampling points that yielded Calonectria and the number (and percentage) of Calonectria isolates obtained decreased with increasing depth of the soil. More than 84% of the isolates were obtained from the 0-20 and 20-40 cm soil layers. The deeper soil layers had comparatively lower numbers but still harbored a considerable number of Calonectria. The diversity of five species in the C. kyotensis species complex decreased with increasing soil depth. The genotypes of isolates in each Calonectria species were determined by tef1 and tub2 gene sequences. For each species in the C. kyotensis species complex, in most cases, the number of genotypes decreased with increasing soil depth. The 0-20 cm soil layer contained all of the genotypes of each species. To our knowledge, this study presents the first report of C. orientalis isolated in China. This species was isolated from the 40-60 and 60-80 cm soil layers at only one sampling point, and only one genotype was present. This study has enhanced our understanding of the species diversity and distribution characteristics of Calonectria in different soil layers.

Project description:Eucalyptus spp. are extensively cultivated in southern China because of their adaptability and versatile timber production. Calonectria leaf blight caused by Calonectria species is considered a major threat to Eucalyptus trees planted in China. The GuangXi Zhuang Autonomous Region is the provincial region with the largest distribution of Eucalyptus plantations in China. The present study aimed to expound the species diversity and pathogenicity of Calonectria isolates obtained from the soil of Eucalyptus plantations in GuangXi. A total of 188 Calonectria isolates were recovered from the soil located close to Eucalyptus trees, and the isolates were identified based on the DNA sequence comparisons of the four partial regions of the translation elongation factor 1-alpha (tef1), β-tubulin (tub2), calmodulin (cmdA), and histone H3 (his3) genes. The isolates were identified as Calonectria aconidialis (74.5%), C. hongkongensis (21.3%), C. pseudoreteaudii (2.1%), C. kyotensis (1.6%), and C. chinensis (0.5%). The inoculation results indicated that 40 isolates representing five Calonectria species were pathogenic to the three Eucalyptus genotypes. Two inoculated experiments consistently showed that the longest lesions were produced by the isolates of C. aconidialis. Some isolates of C. aconidialis, C. hongkongensis, and C. kyotensis produced significantly longer lesions than the positive controls, but not the isolates of C. pseudoreteaudii or C. chinensis. These results indicated that Calonectria isolated from the soil may pose a threat to Eucalyptus plantations. Some Calonectria isolates of the same species differed significantly in their virulence in the tested Eucalyptus genotypes. The resistance of different Eucalyptus genotypes to Calonectria isolates within the same species was inconsistent. The inoculation results in this study suggested that many Calonectria isolates in each species had different levels of pathogenicity, and many Eucalyptus genotypes need to be tested to select disease-resistant Eucalyptus genetic materials in the future. The results of the present study enhance our knowledge of species diversity and the potential damage caused by Calonectria in the soil of Eucalyptus plantations. Our results also provide new insights into the breeding of disease-resistant Eucalyptus genotypes for controlling Calonectria leaf blight in China in the future.

Dataset Information

Species Diversity, Mating Strategy and Pathogenicity of Calonectria Species from Diseased Leaves and Soils in the Eucalyptus Plantation in Southern China.

Publications

Species Diversity, Mating Strategy and Pathogenicity of <i>Calonectria</i> Species from Diseased Leaves and Soils in the <i>Eucalyptus</i> Plantation in Southern China.

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