Nonpathogenic isolates of the citrus black spot fungus, Guignardia citricarpa, identified as a cosmopolitan endophyte of woody plants, G-mangiferae (Phyllosticta capitalensis)
Nonpathogenic isolates of the citrus black spot fungus, Guignardia citricarpa, identified as a cosmopolitan endophyte of woody plants, G-mangiferae (Phyllosticta capitalensis)
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DOI：
10.1094/phyto.2002.92.5.464
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发表时间：
2002-05-01
期刊：
影响因子：
3.2
通讯作者：
Azevedo, JL
中科院分区：
文献类型：
--
作者：
Baayen, RP;Bonants, PJM;Azevedo, JL
对 Guignardia citricarpa sensu lato（无性型：Phyllosticta citricarpa）的种群结构进行了调查，该真菌对柑橘具有致病性，受到欧盟和美国植物检疫立法的管辖。内部转录间隔序列揭示了柑橘棉中两个系统发育上不同的类群。这种区别得到了扩增片段长度多态性分析的支持，该分析也支持排除明显被错误分类为 G. citricarpa 的两个分离株。在樱桃汤琼脂上，但在其他培养基上，I 组分离株的生长速率低于 II 组分离株的生长速率。分生孢子尺寸相似，但第一组分离物形成的分生孢子具有几乎不可见的粘液鞘，而第二组分离物形成的分生孢子具有厚鞘。属于第一组的分离株的培养物产生罕见的不育子囊壳，而第二组的大多数分离株形成可育子囊壳。属于第一组的分离株的菌落比第二组的颜色浅，具有更宽的半透明外区和叶状而不是整个边缘。在燕麦琼脂上，仅第 I 组分离物形成黄色色素，第 I 组含有来自柑橘类水果的菌株，具有典型的黑斑病斑（直径 1 至 10 毫米），通常含有分生孢子器。第二组含有来自多种宿主物种的内生菌株，以及来自无症状柑橘类水果或具有微小斑点（直径<2毫米）但无分生孢子器的水果的菌株。这些观察结果支持了缓慢生长的柑橘G. citricarpa 致病分离株和形态相似的快速生长的非致病分离株之间的历史区别。后者被证明属于芒果 G. mangiferae (P. Capitalensis)，这是一种普遍存在的木本植物内生菌，有许多可能的异名，包括 G. endophyllicola、G. psidii、P. anacardiacearum 和 P. theacearum。 G. mangiferae 发生在欧盟和美国的许多宿主物种（包括柑橘）上，并且不会引起柑橘黑斑病症状，因此有理由将其排除在检疫措施之外。
The population structure of Guignardia citricarpa sensu lato (anamorph: Phyllosticta citricarpa), a fungus of which strains pathogenic to citrus are subject to phytosanitary legislation in the European Union and the United States, was investigated. Internal transcribed spacer sequences revealed two phylogenetically distinct groups in G. citricarpa. This distinction was supported by amplified fragment length polymorphism analysis that also supported the exclusion of two isolates that had apparently been misclassified as G. citricarpa. On cherry decoction agar, but not on other media, growth rates of group I isolates were lower than those of group II isolates. Conidial dimensions were similar, but group I isolates formed conidia with barely visible mucoid sheaths, whereas those of group II formed conidia with thick sheaths. Cultures of isolates belonging to group I produced rare infertile perithecia, whereas fertile perithecia were formed by most isolates of group II. Colonies of isolates belonging to group I were less dark than those of group II, with a wider translucent outer zone and a lobate rather than entire margin. On oatmeal agar, exclusively group I isolates formed a yellow pigment, Group I harbored strains from citrus fruits with classical black spot lesions (1 to 10 mm in diameter) usually containing pycnidia. Group II harbored endophytic strains from a wide range of host species, as well as strains from symptomless citrus fruits or fruits with minute spots (< 2-mm diameter) without pycnidia. These observations support the historic distinction between slowly growing pathogenic isolates and morphologically similar fast-growing, nonpathogenic isolates of G. citricarpa. The latter proved to belong to G. mangiferae (P. capitalensis), a ubiquitous endophyte of woody plants with numerous probable synonyms including G. endophyllicola, G. psidii, P. anacardiacearum, and P. theacearum. G. mangiferae occurs in the European Union and the United States on many host species including citrus, and does not cause symptoms of citrus black spot, justifying its exclusion from quarantine measures.