Institute of Biology, College of Science, University of the Philippines Diliman, Quezon City, Philippines.
Institute of Biology, College of Science, University of the Philippines Diliman, Quezon City, Philippines; Natural Sciences Research Institute, College of Science, University of the Philippines Diliman, Quezon City, Philippines.
Fungal Biol. 2021 Jun;125(6):435-446. doi: 10.1016/j.funbio.2021.01.001. Epub 2021 Jan 11.
High amount of copper is toxic to most organisms, but endophytic fungi can develop survival strategies to tolerate and respond to environmental stressors such as heavy metal contaminants. While high copper induces oxidative stress, it is still unclear which genes are associated with copper tolerance. Here, we performed a metatranscriptome analysis of endophytic fungi isolated from a black nightshade plant Solanum nigrum L. growing on mine tailings of a gold processing area. Initial screening revealed the presence of a copper-tolerant strain of Fusarium oxysporum, designated as IB-SN1W, which tolerated up to 1000 ppm and 300 ppm copper in solid and liquid media, respectively. Differential gene expression analysis by RNA sequencing showed that 23% of contigs are uniquely expressed in the copper-treated fungus. These genes are involved in copper ion import, polyamine transport, oxidoreductase activity, and oxidative stress response. Catalase transcripts were also highly upregulated in IB-SN1W compared to a non-tolerant F. oxysporum strain. Catalase inhibition decreased copper-tolerance in IB-SN1W, while the addition of antioxidants prevented the copper-dependent growth inhibition in the non-tolerant strain. Overall, these results suggest that oxidative stress response contributes to copper tolerance in F. oxysporum.
高浓度的铜对大多数生物都是有毒的，但内生真菌可以发展出生存策略来耐受和应对环境胁迫，如重金属污染物。虽然高浓度的铜会引起氧化应激，但目前尚不清楚哪些基因与铜耐受性有关。在这里，我们对生长在金矿处理区尾矿上的黑茄内生真菌进行了宏转录组分析。初步筛选显示，存在一种耐铜的尖孢镰刀菌（Fusarium oxysporum）菌株，命名为 IB-SN1W，它在固体和液体培养基中分别耐受高达 1000 ppm 和 300 ppm 的铜。RNA 测序的差异基因表达分析显示，23%的基因在铜处理的真菌中是独特表达的。这些基因参与铜离子导入、多胺转运、氧化还原酶活性和氧化应激反应。与不耐铜的尖孢镰刀菌菌株相比，IB-SN1W 中的过氧化氢酶转录本也高度上调。在 IB-SN1W 中抑制过氧化氢酶会降低其耐铜性，而在不耐铜的菌株中添加抗氧化剂可以防止铜依赖性生长抑制。总的来说，这些结果表明，氧化应激反应有助于尖孢镰刀菌耐铜。
