Calonectria属包括各种农业病原体,园艺,和林业作物。Calonectria的物种通常从土壤中收集,水果,叶子,茎,和根。从土壤中分离出的一些Calonectria物种被认为是重要的植物病原体。了解Calonectria物种在不同土壤层中的物种多样性和分布特征将有助于我们阐明其对植物的长期潜在危害及其传播模式。据我们所知,尚未对Calonectria在不同土壤层中的物种多样性和分布特征进行系统研究。在这项研究中,在中国南方一个15年生尾叶桉树杂交人工林的100个采样点,从五个土壤层(0-20、20-40、40-60、60-80和80-100cm)收集了1000个土壤样品。从100个采样点中的93个获得了所有五个土壤层中总共存在的1037个Calonectria分离株。根据翻译延伸因子1-alpha(tef1)的DNA序列比较鉴定了1037个分离株,β-微管蛋白(tub2),calmodulin(cmdlet),和组蛋白H3(His3)基因区,以及形态特征的组合。这些分离株被鉴定为红根氏梭菌(665株;64.1%),C.aconidialis(250个分离株;24.1%),c.kyotensis(58个分离株;5.6%),C.ilicicola(47株;4.5%),C.中国(2个分离株;0.2%),和东方梭菌(15个分离株;1.5%)。除了C.Orientalis,它位于十字花菜科物种复合体中,其他五个物种属于C.kyotensis物种复合体。结果表明,产生Calonectria的采样点的数量和获得的Calonectria分离株的数量(和百分比)随着土壤深度的增加而减少。超过84%的分离株是从0-20和20-40厘米的土壤层获得的。较深的土壤层的数量相对较低,但仍有大量的Calonectria。C.kyotensis物种复合体中五个物种的多样性随着土壤深度的增加而降低。通过tef1和tub2基因序列确定每个Calonectria物种中分离株的基因型。对于C.kyotensis物种复合体中的每个物种,在大多数情况下,基因型数量随着土壤深度的增加而减少。0-20厘米的土壤层包含每个物种的所有基因型。据我们所知,本研究首次报道了在中国分离的东方假草。该物种仅在一个采样点从40-60和60-80厘米的土壤层中分离出来,只存在一种基因型。这项研究增强了我们对Calonectria在不同土壤层中的物种多样性和分布特征的了解。
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.