Agri-Science Queensland, Department of Employment, Economic Development and Innovation, P.O. Box 102, Toowoomba, Qld 4350, Australia; corresponding author e-mail:
Persoonia. 2011 Dec;27:80-9. doi: 10.3767/003158511X617110. Epub 2011 Dec 2.
The identification of Diaporthe (anamorph Phomopsis) species associated with stem canker of sunflower (Helianthus annuus) in Australia was studied using morphology, DNA sequence analysis and pathology. Phylogenetic analysis revealed three clades that did not correspond with known taxa, and these are believed to represent novel species. Diaporthe gulyae sp. nov. is described for isolates that caused a severe stem canker, specifically pale brown to dark brown, irregularly shaped lesions centred at the stem nodes with pith deterioration and mid-stem lodging. This pathogenicity of D. gulyae was confirmed by satisfying Koch's Postulates. These symptoms are almost identical to those of sunflower stem canker caused by D. helianthi that can cause yield reductions of up to 40 % in Europe and the USA, although it has not been found in Australia. We show that there has been broad misapplication of the name D. helianthi to many isolates of Diaporthe (Phomopsis) found causing, or associated with, stem cankers on sunflower. In GenBank, a number of isolates had been identified as D. helianthi, which were accommodated in several clades by molecular phylogenetic analysis. Two less damaging species, D. kochmanii sp. nov. and D. kongii sp. nov., are also described from cankers on sunflower in Australia.
对与向日葵茎溃疡相关的 Diaporthe（无性型 Phomopsis）种的鉴定进行了研究，使用形态学、DNA 序列分析和病理学方法。系统发育分析揭示了三个不对应于已知分类群的分支，这些分支被认为代表新的物种。Diaporthe gulyae sp. nov. 是为引起严重茎溃疡的分离物而描述的，特别是浅棕色到深棕色，形状不规则，病变位于茎节点中心，髓质恶化和中茎倒伏。D. gulyae 的致病性通过满足科赫假设得到了证实。这些症状与欧洲和美国向日葵茎溃疡引起的 D. helianthi 引起的症状几乎相同，尽管在澳大利亚尚未发现，但已导致产量减少高达 40%。我们表明，已经广泛错误地将 D. helianthi 这个名称应用于许多被发现引起或与向日葵茎溃疡相关的 Diaporthe（Phomopsis）分离物上。在 GenBank 中，许多分离物被鉴定为 D. helianthi，通过分子系统发育分析它们被归入几个分支。还从澳大利亚向日葵的溃疡中描述了两种危害性较小的物种，D. kochmanii sp. nov. 和 D. kongii sp. nov.。
