Departamento de Fitopatologia, Universidade Federal de Viçosa, Viçosa, MG, 36570-900, Brazil.
Braz J Microbiol. 2023 Sep;54(3):1899-1914. doi: 10.1007/s42770-023-01047-6. Epub 2023 Jun 30.
The myrtle rust (MR), caused by Austropuccinia psidii, is a worldwide threat to the cultivated and wild Myrtaceae. Originally from the neotropics, it has spread to North America, Africa, and Asia and has reached geographically isolated areas in the Pacific and Australasia. It is attacking native species in those new ranges and is still spreading and causing great concern for the damage caused to endemic Myrtaceae, and to the environment. Classical biological control is regarded as the most sustainable management option for mitigating such biological invasions. However, there are no examples of introductions of host-specific co-evolved natural enemies of plant pathogens, from their native range, as a management strategy for plant pathogens. In order to explore this neglected approach, a survey of potential fungal natural enemies of A. psidii was initiated recently in the state of Minas Gerais (Brazil). Several purported mycoparasites have been collected from A. Psidii pustules formed on myrtaceous hosts. This included some isolates of dematiaceous fungi recognized as having a Cladosporium-like morphology. Here we present the results of the investigation aimed at elucidating their identity through a polyphasic taxonomic approach. Besides morphological and cultural features, molecular analyses using sequences of translation elongation factor 1-α (EF1) and actin (ACT) were performed. The combination of data generated is presented herein and placed all Cladosporium-like isolates in six species of Cladosporium, namely, Cladosporium angulosum, C. anthropophilum, C. bambusicola, C. benschii, C. guizhouense, and C. macadamiae. None of these have ever been recorded in association with A. psidii. Now, with the identification of these isolates at hand, an evaluation of biocontrol potential of these fungi will be initiated. In contrast with the ready finding of fungicolous (possibly mycoparasitic) fungi on MR in this study, no evidence of those was recorded from Australasia until now.
叶肿锈菌（MR）由 Austropuccinia psidii 引起，是对栽培和野生桃金娘科植物的全球性威胁。它最初来自新热带地区，现已传播到北美洲、非洲和亚洲，并已到达太平洋和澳大拉西亚的地理隔离地区。它正在攻击这些新范围内的本地物种，并且仍然在传播，并对特有桃金娘科植物和环境造成极大的破坏。传统的生物防治被认为是减轻此类生物入侵的最可持续管理选择。然而，从其原生范围引入植物病原菌的宿主特异性共同进化的天然天敌作为一种管理策略，尚无实例。为了探索这种被忽视的方法，最近在米纳斯吉拉斯州（巴西）启动了一项针对 A. psidii 潜在真菌天敌的调查。从桃金娘科寄主上形成的 A. Psidii 脓疱中收集了几种据称是真菌的外生菌根真菌。其中包括一些被认为具有类似黑曲霉形态的暗色真菌分离株。在这里，我们通过多相分类学方法介绍了旨在阐明其身份的调查结果。除了形态学和培养特征外，还使用翻译延伸因子 1-α（EF1）和肌动蛋白（ACT）序列的分子分析进行了分析。本文介绍了生成的数据组合，并将所有类似黑曲霉的分离株置于黑曲霉属的六个种中，即角状黑曲霉、人类嗜皮黑曲霉、竹黑曲霉、Bensch 黑曲霉、贵州黑曲霉和 Macadam 黑曲霉。这些分离株以前从未与 A. psidii 相关联。现在，这些分离株的鉴定已经完成，将开始评估这些真菌的生物防治潜力。与本研究中在 MR 上容易发现菌根真菌（可能是真菌捕食性）的情况相反，到目前为止，在澳大拉西亚还没有记录到这些真菌的证据。
