戊唑醇重复施药土壤中抗药性烟曲霉及其cyp51A突变的累积性和传递性

Invasive aspergillosis caused by infection of Aspergillus fumigatus is the most inportant lethal factor for the immunocompromised patients. Triazoles are the mainstay of therapy in infections with Aspergillus fumigatus. However, the increasing resistance of Aspergillus fumigatus to triazole drugs becomes a new challenge in the management of invasive aspergillosis. Based on the inducible resistance of Aspergillus fumigatus with random and multiple mutations in cyp51A by triazole fungicides found in our studies, this study will be conducted in the greenhouses for the production of strawberry and cherry tomato as two kinds of crop plants and fruits with repeated applications of the triazole fungicide tebuconazole to investigate: 1) residual dynamics of tebuconazole, abundance of Aspergillus fumigatus, cumulativity of cyp51A mutations, dynamics of resistant Aspergillus fumigatus in soil and on plant leave and fruits, respectively. 2) the persistence of resistant Aspergillus fumigatus on/in the fruits in the process of their storage. 3) variation of residual tebuconazole, abundance of total and resistant Aspergillus fumigatus in soil after harvest. The study will helpful for the understanding of cumulativity and transmissibility of resistant Aspergillus fumigatus in soil successively recieved applicaions of tebuconazole.

烟曲霉引起的侵袭性曲霉病是免疫缺陷人群重要致死因子，其治疗主要依赖于三唑类药物。但是，烟曲霉的抗药性日趋严重，已成为临床治疗中的棘手问题。本项目在课题组已证明三唑类杀菌剂诱导烟曲霉抗药性及其相关cyp51A突变的随机性和多样性的基础上，以常用三唑类杀菌剂戊唑醇为例，以不同植株和果实类型的草莓和圣女果为作物对象，在高频、高剂量使用杀菌剂的设施大棚环境中研究：1）土壤、作物叶片、果实中戊唑醇残留特征、烟曲霉丰度、烟曲霉cyp51A突变累积性、抗药性烟曲霉消长特征；2）果实储藏过程中的抗药性烟曲霉持留性；3）停止施药后土壤中戊唑醇残留、烟曲霉丰度、抗药性烟曲霉变化动态。以期揭示戊唑醇使用过程中土壤中抗药性烟曲霉及其相关cyp51A突变的累积性；明确戊唑醇施用剂量与田间土壤中抗药性烟曲霉形成的关系；阐明土壤中抗药性烟曲霉经食物链进入人体的可能性，从三唑类杀菌剂使用角度提出烟曲霉抗药性的防控途径。

烟曲霉引起的侵袭性曲霉病是免疫缺失人群主要致死因子，其治疗主要依赖于三唑类药物。但是，烟曲霉的抗药性日趋严重，已成为临床治疗中的棘手问题。本项目研究了土壤环境中抗药性烟曲霉及其抗性相关cyp51A突变的多样性；戊唑醇对土壤中烟曲霉敏感性的影响；田间戊唑醇施用与烟曲霉敏感性变化；田间唑类杀菌剂残留驱动抗性烟曲霉的形成与传播。结果表明：1）2014-2018年间，土壤环境中抗性烟曲霉比例在五年间上升了1.2倍，抗性菌株的突变机制也在逐年增加；2）土壤-番茄系统中戊唑醇使用可导致烟曲霉抗药性形成，特别是大棚种植条件下戊唑醇的使用更有利于抗性烟曲霉的发展；3）戊唑醇使用后番茄植株存在抗药性烟曲霉，提示抗药性烟曲霉经食物链传递的风险；4）大量农田土壤中唑类杀菌剂残留、烟曲霉敏感性分析表明，农田土壤中唑类杀菌剂使用和残留是烟曲霉抗药性形成的主要驱动因子；5）戊唑醇对靶标植物病原菌和烟曲霉诱导抗性存在手性差异，但是对靶标病原菌毒力强的对映体诱导烟曲霉产生抗药性的风险也高。因此，为了降低抗性烟曲霉发展过程中的选择压，应尽可能地减少环境中唑类杀菌剂的使用并延长其使用间隔期。