Phomopsis husk rot (PHR) in macadamia is a disease of economic importance in major commercial production areas in Australia and South Africa. Effective control of PHR is hindered by limited knowledge about its aetiology and epidemiology. The diversity and pathogenicity of more than 50 isolates of Diaporthe associated with PHR in macadamia orchards in Australia and South Africa was assessed. Multilocus phylogenetic analyses of DNA sequences of the ITS, tef1α, and tub2 gene loci revealed four novel clades that are described as Diaporthe australiana sp. nov., D. drenthii sp. nov., D. macadamiae sp. nov., and D. searlei sp. nov. Pathogenicity tests with representative isolates found that all four species caused PHR of varying severity between and within species, as well as between the two macadamia cultivars HAES 344 and HAES 816. The Australian species, D. australiana, was the most aggressive species compared with the three South African species. This study improves our understanding of the aetiology of PHR in macadamia and paves the way for more effective disease management.

中文翻译：

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澳大利亚和南非澳洲坚果的拟茎点腐病由新的 Diaporthe 物种引起

澳洲坚果中的拟茎点腐病 (PHR) 是一种在澳大利亚和南非的主要商业生产区具有重要经济意义的疾病。PHR 的有效控制受到对其病因和流行病学知识有限的阻碍。评估了澳大利亚和南非澳洲坚果果园中 50 多个与 PHR 相关的 Diaporthe 分离株的多样性和致病性。对 ITS、tef1α 和 tub2 基因位点 DNA 序列的多位点系统发育分析揭示了四个新的进化枝，它们被描述为 Diaporthe australiana sp。nov., D. drenthii sp. nov., D. 澳洲坚果 sp. 11 月，和 D. searlei sp。十一月 对代表性分离株的致病性测试发现，所有四个物种在物种之间和物种内，以及两个澳洲坚果栽培品种 HAES 344 和 HAES 816 之间都引起了不同严重程度的 PHR。与三种南非物种相比，澳大利亚物种 D. australiana 是最具侵略性的物种。这项研究提高了我们对澳洲坚果 PHR 病因的理解，并为更有效的疾病管理铺平了道路。