Department of Plant Pathology, University of Minnesota, St Paul, Minnesota 55108
Department of Horticultural Science, University of Minnesota, St Paul, Minnesota 55108.
Mycologia. 2015 Jan-Feb;107(1):66-79. doi: 10.3852/14-004. Epub 2014 Oct 24.
Cryptodiaporthe corni is the causal agent of a destructive disease called golden canker, which affects Cornus alternifolia, known as the pagoda or alternate-leaved dogwood. Due to the association between Cr. corni and pagoda dogwood, we sought to determine whether this fungus was capable of living as an endophyte in pagoda dogwood and causing this disease. Forty asymptomatic stems of plants growing in nature were sampled from five sites across Minnesota. Cryptodiaporthe corni was present in more than half (62.5%) of the stems. Asymptomatic nursery material also was sampled, and the fungus was isolated from a small percentage (20%) of them. Inoculations carried out in the field and greenhouse suggested the endophytic isolates of Cr. corni were capable of causing disease. Asymptomatic stems of trees in the field inoculated with non-colonized (control) grain seed developed golden canker as frequently as those inoculated with grain seed colonized by Cr. corni, suggesting that the fungus was already present in these plants. In greenhouse pathogenicity trials an isolate of Cr. corni obtained from an asymptomatic stem was capable of causing golden canker disease, thus demonstrating causality, fulfilling Koch's postulates. The taxonomic placement of Cr. corni within Cryphonectriaceae was determined. Phylogenetic analysis of the ITS rDNA and β-tubulin gene regions, along with morphological characteristics, suggested Cr. corni is distinct from other genera within this family. Therefore, we propose a new genus, Aurantioporthe, as well as the new combination, A. corni, to accommodate this species within Cryphonectriaceae.
Cryptodiaporthe corni 是一种破坏性疾病的病原体，这种疾病被称为金溃疡，它会影响 Cornus alternifolia，也就是宝塔或交替叶山茱萸。由于 Cr. corni 与宝塔山茱萸之间的联系，我们试图确定这种真菌是否能够作为内寄生菌生活在宝塔山茱萸中并导致这种疾病。从明尼苏达州的五个地点采集了 40 个无症状的自然生长植物茎。Cr. corni 存在于一半以上（62.5%）的茎中。也采集了无症状的苗圃材料，真菌从一小部分（20%）中分离出来。在野外和温室中进行的接种表明，Cr. corni 的内生分离物能够引起疾病。用未感染（对照）谷物种子接种的野外无症状茎与用 Cr. corni 感染的谷物种子接种的茎一样频繁地发展为金溃疡，这表明真菌已经存在于这些植物中。在温室致病性试验中，从无症状茎中获得的 Cr. corni 分离物能够引起金溃疡疾病，从而证明了因果关系，满足了科赫的假设。确定了 Cr. corni 在 Cryphonectriaceae 中的分类位置。ITS rDNA 和β-微管蛋白基因区域的系统发育分析，以及形态特征，表明 Cr. corni 与该科内的其他属不同。因此，我们提出了一个新属 Aurantioporthe，以及新的组合 A. corni，将这个物种纳入 Cryphonectriaceae。
