Laboratory of Pesticide Science, Agricultural University of Athens, Athens, Greece.
Laboratory of Biological Control of Pesticides, Benaki Phytopathological Institute, Kifissia, Greece.
PLoS One. 2020 May 29;15(5):e0233916. doi: 10.1371/journal.pone.0233916. eCollection 2020.
The olive tree (Olea europaea L.) is the most important oil-producing crop of the Mediterranean basin. However, although plant protection measures are regularly applied, disease outbreaks represent an obstacle towards the further development of the sector. Therefore, there is an urge for the improvement of plant protection strategies based on information acquired by the implementation of advanced methodologies. Recently, heavy fungal infections of olive fruits have been recorded in major olive-producing areas of Greece causing devastating yield losses. Thus, initially, we have undertaken the task to identify their causal agent(s) and assess their pathogenicity and sensitivity to fungicides. The disease was identified as the olive anthracnose, and although Colletotrichum gloeosporioides and Colletotrichum acutatum species complexes are the two major causes, the obtained results confirmed that in Southern Greece the latter is the main causal agent. The obtained isolates were grouped into eight morphotypes based on their phenotypes, which differ in their sensitivities to fungicides and pathogenicity. The triazoles difenoconazole and tebuconazole were more toxic than the strobilurins being tested. Furthermore, a GC/EI/MS metabolomics model was developed for the robust chemotaxonomy of the isolates and the dissection of differences between their endo-metabolomes, which could explain the obtained phenotypes. The corresponding metabolites-biomarkers for the discrimination between morphotypes were discovered, with the most important ones being the amino acids L-tyrosine, L-phenylalanine, and L-proline, the disaccharide α,α-trehalose, and the phytotoxic pathogenesis-related metabolite hydroxyphenylacetate. These metabolites play important roles in fungal metabolism, pathogenesis, and stress responses. The study adds critical information that could be further exploited to combat olive anthracnose through its monitoring and the design of improved, customized plant protection strategies. Also, results suggest the necessity for the comprehensive mapping of the C. acutatum species complex morphotypes in order to avoid issues such as the development of fungicide-resistant genotypes.
油橄榄（Olea europaea L.）是地中海盆地最重要的油料作物。然而，尽管定期采取植物保护措施，但疾病爆发仍是该行业进一步发展的障碍。因此，迫切需要改进植物保护策略，方法是通过实施先进方法获取信息。最近，希腊主要橄榄产区记录到橄榄果实严重真菌感染，导致产量毁灭性损失。因此，我们最初的任务是确定其致病因子并评估其致病性和对杀菌剂的敏感性。该疾病被确定为橄榄炭疽病，尽管炭疽菌属 Colletotrichum gloeosporioides 和 Colletotrichum acutatum 复合种是两个主要原因，但获得的结果证实，在希腊南部，后者是主要的致病因子。根据表型将获得的分离物分为八个形态型，它们在对杀菌剂的敏感性和致病性方面存在差异。所测试的三唑类杀菌剂如 difenoconazole 和 tebuconazole 比 strobilurins 毒性更大。此外，还为分离物的稳健化学生态分类学和内代谢组之间差异的剖析开发了 GC/EI/MS 代谢组学模型，这可以解释获得的表型。发现了用于区分形态型的代谢物生物标志物，最重要的是氨基酸 L-酪氨酸、L-苯丙氨酸和 L-脯氨酸、二糖α,α-海藻糖和有毒的与发病相关的代谢物 4-羟基苯乙酸。这些代谢物在真菌代谢、发病机制和应激反应中发挥重要作用。该研究提供了重要信息，可进一步用于通过监测和设计改进的、定制的植物保护策略来防治橄榄炭疽病。此外，结果表明有必要对 C. acutatum 复合种形态型进行全面绘图，以避免出现杀菌剂抗性基因型发展等问题。
