链格孢菌是一种普遍存在的土壤传播真菌,能够在多种植物中引起疾病,有时在人类中引起疾病。虽然来自受感染植物的A.alternata种群受到了极大的关注,对其土壤种群的了解相对较少,包括其种群遗传结构和抗真菌敏感性。此外,在过去的二十年里,温室在全世界的食品和观赏植物生产中变得越来越重要,但是温室如何影响微生物病原体,例如A.alternata种群仍然未知。不同于开阔的农田,温室通常被更密集地种植,每个温室都是一个相对较小和孤立的空间,温度和湿度高于周围环境。以前的研究表明,温室种群的两种常见霉菌,烟曲霉和交替曲霉,在中国西南部的一个小社区中,差异很大。然而,当地温室之间的物理分离对大规模人口结构的相对贡献仍然未知。这里,我们从石家庄的七个温室中分离出了A.alternata菌株,中国东北。对它们的遗传多样性和三唑敏感性进行了分析,并与昆明9个温室的242个分离株进行了比较,中国西南。结果表明,与两个遥远的地理区域之间的整体遗传变异相似,位于彼此相距<1km的温室的隔离对整体遗传变异的贡献相似。此外,我们的结果表明,温室可能是三唑抗性的重要来源,温室对不同三唑的抗性菌株的频率通常不同。
目的:温室对粮食生产和粮食安全越来越重要。然而,我们对温室如何导致土壤微生物种群遗传变异的理解非常有限。在这项研究中,我们获得并分析了石家庄市七个温室中世界性真菌病原体链格孢菌的土壤种群,中国东北。我们的分析显示,高比例的分离株对农用三唑类杀菌剂和医用三唑类药物具有抗性,包括对两组三唑的交叉抗性。此外,我们发现,位于几公里范围内的A.alternata的温室种群表现出与东北和西南地区相距2000多公里的种群相似的遗传分化水平。我们的研究表明,这种和潜在的其他真菌病原体的温室种群代表了重要的生态位和对粮食安全和人类健康的新威胁。
Alternaria alternata is a ubiquitous soil-borne fungus capable of causing diseases in a variety of plants and occasionally in humans. While populations of A. alternata from infected plants have received significant attention, relatively little is known about its soil populations, including its population genetic structure and antifungal susceptibilities. In addition, over the last two decades, greenhouses have become increasingly important for food and ornamental plant production throughout the world, but how greenhouses might impact microbial pathogens such as A. alternata populations remains largely unknown. Different from open crop fields, greenhouses are often more intensively cultivated, with each greenhouse being a relatively small and isolated space where temperature and humidity are higher than surrounding environments. Previous studies have shown that greenhouse populations of two common molds, Aspergillus fumigatus and A. alternata, within a small community in southwestern China were variably differentiated. However, the relative contribution of physical separation among local greenhouses to the large-scale population structure remains unknown. Here, we isolated strains of A. alternata from seven greenhouses in Shijiazhuang, northeast China. Their genetic diversity and triazole susceptibilities were analyzed and compared with each other and with 242 isolates from nine greenhouses in Kunming, southwest China. Results showed that the isolation of greenhouses located <1 km from each other locally contributed similarly to the overall genetic variation as that between the two distant geographic regions. In addition, our results indicate that greenhouses could be significant sources of triazole resistance, with greenhouses often differing in their frequencies of resistant strains to different triazoles.
OBJECTIVE: Greenhouses have become increasingly important for food production and food security. However, our understanding of how greenhouses may contribute to genetic variations in soil microbial populations is very limited. In this study, we obtained and analyzed soil populations of the cosmopolitan fungal pathogen Alternaria alternata in seven greenhouses in Shijiazhuang, northeast China. Our analyses revealed high proportions of isolates being resistant to agricultural triazole fungicides and medical triazole drugs, including cross-resistance to both groups of triazoles. In addition, we found that greenhouse populations of A. alternata located within a few kilometers showed similar levels of genetic differentiation as those separated by over 2,000 km between northeast and southwest China. Our study suggests that greenhouse populations of this and potentially other fungal pathogens represent an important ecological niche and an emerging threat to food security and human health.