Department of Plant Pathology, Iowa State University, Ames, IA, USA.
Phytopathology. 2010 Apr;100(4):345-55. doi: 10.1094/PHYTO-100-4-0345.
Sooty blotch and flyspeck (SBFS) fungi on apple fruit were sampled from nine orchards in four midwestern U.S. states during 2000 and 30 orchards in 10 eastern U.S. states during 2005 in order to estimate taxonomic diversity and discern patterns of geographic distribution. Forty apple fruit per orchard were arbitrarily sampled and colonies of each mycelial phenotype were counted on each apple. Representative colonies were isolated, cultures were purified, and DNA was extracted. For representative isolates, the internal transcribed spacer (ITS) and large subunit (LSU) regions of ribosomal DNA were amplified and sequenced. In total, 60 SBFS putative species were identified based on ITS sequences and morphological characteristics; 30 of these were discovered in the 2005 survey. Modified Koch's postulates were fulfilled for all 60 species in an Iowa orchard; colonies resulting from inoculation of apple fruit were matched to the original isolates on the basis of mycelial type and ITS sequence. Parsimony analysis for LSU sequences from both surveys revealed that 58 putative SBFS species were members of the Dothideomycetes, 52 were members of the Capnodiales, and 36 were members of the Mycosphaerellaceae. The number of SBFS species per orchard varied from 2 to 15. Number of SBFS species and values of the Margalef and Shannon indexes were significantly (P < 0.05) lower in 21 orchards that had received conventional fungicide sprays during the fruit maturation period than in 14 unsprayed orchards. Several SBFS species, including Schizothyrium pomi, Peltaster fructicola, and Pseudocercosporella sp. RH1, were nearly ubiquitous, whereas other species, such as Stomiopeltis sp. RS5.2, Phialophora sessilis, and Geastrumia polystigmatis, were found only within restricted geographic regions. The results document that the SBFS complex is far more taxonomically diverse than previously recognized and provide strong evidence that SBFS species differ in geographic distribution. To achieve more efficient management of SBFS, it may be necessary to understand the environmental biology of key SBFS species in each geographic region.
为了评估分类多样性并辨别地理分布模式，我们于 2000 年从美国中西部四个州的 9 个果园中以及于 2005 年从美国东部十个州的 30 个果园中采集了苹果果实上的煤污斑和蝇粪斑（SBFS）真菌。每个果园任意采集 40 个苹果果实，统计每个苹果上的每一菌丝体表型的菌落数。代表性菌落被分离出来，培养物被纯化，DNA 被提取出来。对于代表性分离物，核糖体 DNA 的内部转录间隔区（ITS）和大亚基（LSU）区域被扩增和测序。总共根据 ITS 序列和形态特征鉴定出 60 种 SBFS 假定种；其中 30 种是在 2005 年的调查中发现的。在爱荷华州的一个果园中完成了所有 60 种的改良柯赫氏假设；根据菌丝体类型和 ITS 序列，从苹果果实接种产生的菌落与原始分离物相匹配。两个调查的 LSU 序列简约分析表明，58 种假定的 SBFS 种是 Dothideomycetes 的成员，52 种是 Capnodiales 的成员，36 种是 Mycosphaerellaceae 的成员。每个果园的 SBFS 种数从 2 到 15 不等。在果实成熟期间接受常规杀菌剂喷雾处理的 21 个果园中，SBFS 种数和 Margalef 和 Shannon 指数的值明显（P <0.05）低于 14 个未喷洒果园。一些 SBFS 种，包括 Schizothyrium pomi、Peltaster fructicola 和 Pseudocercosporella sp. RH1，几乎无处不在，而其他种，如 Stomiopeltis sp. RS5.2、Phialophora sessilis 和 Geastrumia polystigmatis，则仅存在于有限的地理区域内。结果表明，SBFS 复合体在分类上比以前认识到的要多样化得多，并提供了 SBFS 种在地理分布上存在差异的有力证据。为了实现对 SBFS 的更有效管理，可能有必要了解每个地理区域关键 SBFS 种的环境生物学。
