College of Life Science and Pharmacy, China Three Gorges University, Yichang, 443002, China.
Hubei Key Laboratory of Natural Products Research and Development, College of Life Science and Pharmacy, China Three Gorges University, Yichang, 443002, China.
BMC Microbiol. 2019 Feb 26;19(1):50. doi: 10.1186/s12866-019-1419-5.
Drought and its resulting oxidative damage are the major yield limiting factors for crops in arid and semi-arid regions. Recent studies have found that endophytic fungi coexisting in plants can alleviate biotic or abiotic damage to plant growth and development. In order to screen for the endophytes associated with drought stress, 12 strains of endophytic fungi with high antioxidant activity isolated from riparian plants Myricaria laxiflora were evaluated for their effects in rice by the crude extracts.
Of the 12 endophytic fungi, Aspergillus fumigatus SG-17 functioned most effectively, with the crude extract exhibiting relatively higher antioxidant capacity both in vivo and in vitro. The subsequent MS and NMR analysis showed that the primary substance responsible for the antioxidant activity in the extract was (Z)-N-(4-hydroxystyryl) formamide (NFA), an analogue of coumarin. Enzyme activity assay in nerve cells SH-SY5Y showed that NFA could maintain the membrane integrity and regulate the antioxidase activity under oxidative stress. In rice suffering drought stress, NFA effectively alleviated the harm by regulating the contents of NADPH oxidases, antioxidants and heat shock proteins, all of which are closely related with the reactive oxygen species pathway.
These findings indicated that some endophytes from plants often subjected to flooding and oxidative stress could enhance drought resistance by producing compounds such as NFA to regulate the oxidative pathway.
干旱及其导致的氧化损伤是干旱和半干旱地区作物产量的主要限制因素。最近的研究发现，与植物共生的内生真菌可以减轻生物或非生物因素对植物生长发育的损害。为了筛选与干旱胁迫相关的内生真菌，我们从河岸植物多枝柽柳中分离出 12 株具有较高抗氧化活性的内生真菌，并用粗提物评估其对水稻的影响。
在 12 株内生真菌中，烟曲霉 SG-17 作用效果最显著，其粗提物在体内和体外均表现出相对较高的抗氧化能力。随后的 MS 和 NMR 分析表明，提取物中具有抗氧化活性的主要物质是（Z）-N-（4-羟基肉桂基）甲酰胺（NFA），是香豆素的类似物。在神经细胞 SH-SY5Y 中的酶活性测定表明，NFA 可以在氧化应激下通过维持膜的完整性和调节抗氧化酶的活性来发挥作用。在遭受干旱胁迫的水稻中，NFA 可以通过调节 NADPH 氧化酶、抗氧化剂和热休克蛋白的含量，有效缓解干旱胁迫的危害，这些物质与活性氧途径密切相关。
这些发现表明，一些经常受到洪水和氧化应激的植物内生真菌可以通过产生 NFA 等化合物来调节氧化途径，从而增强其抗旱性。
