Kentucky bluegrass (Poa pratensis L.) is an important species of turfgrass that is commonly planted on golf courses and landscapes all over the world. It is sensitive to salt stress; however, details relating to its molecular mechanisms of salt resistance are not available. We, therefore, analyzed the changes in growth, antioxidant enzyme activity, and microRNA expression in the callus 1 week after treatment with 200 mM NaCl for 12 h, 24 h, 48 h, 96 h, and 144 h. The results demonstrated that callus growth declined and thiobarbituric acid-reactive substance production and cell membrane permeability increased. Treatment with salt increased ascorbate peroxidase, glutathione reductase, superoxide dismutase, catalase, peroxidase, and polyphenol oxidase activity. Changes in the expression levels of microRNAs were observed under salt treatment. The expression of miR162, miR173, miR391, miR408, miR773, and miR857 increased by 70% after 24 h of salt treatment, after which it declined to a level similar to that of the control. The expression level of miR775 and miR827 decreased by 20% after 24 h, and then further decreased by 80% after 144 h. The expression level of miR841 increased by 50% after 24 h of salt treatment, and then stabilized. In contrast, salt treatment increased the expression of the auxin response factors ARF6, ARF8, ARF10, and ARF16 in the callus from 12 to 144 h of salt treatment, during which the expression increased twofold. Gene expression analysis indicated that salt-responsive gene families were regulated by microRNAs in the callus under salinity stress. The activity of antioxidant enzymes is also changing. MiR841 is considered to be a positive regulator of antioxidant enzyme biosynthesis. The present investigation elucidates the manner in which P. pratensis responds to salt stress in the callus, and could be used to inform further studies on the molecular mechanisms of stress tolerance.

中文翻译：

---

盐胁迫下草愈伤组织的抗氧化酶活性和microRNA的相关性。

肯塔基州早熟禾（早熟禾L.）是草皮草的重要物种，通常在世界各地的高尔夫球场和景观上种植。它对盐胁迫敏感；但是，尚无有关其抗盐分子机制的详细信息。因此，我们在用200 mM NaCl处理12小时，24小时，48小时，96小时和144小时1周后，分析了愈伤组织中生长，抗氧化酶活性和microRNA表达的变化。结果表明愈伤组织的生长下降，硫代巴比妥酸反应性物质的产生和细胞膜通透性增加。用盐处理可提高抗坏血酸过氧化物酶，谷胱甘肽还原酶，超氧化物歧化酶，过氧化氢酶，过氧化物酶和多酚氧化酶的活性。在盐处理下观察到微小RNA的表达水平的变化。miR162，miR173，miR391，盐处理24小时后，miR408，miR773和miR857增加了70％，此后下降至与对照组相似的水平。miR775和miR827的表达水平在24小时后下降20％，然后在144小时后进一步下降80％。盐处理24小时后，miR841的表达水平增加了50％，然后稳定下来。相反，盐处理从盐处理的12到144小时增加了愈伤组织中生长素应答因子ARF6，ARF8，ARF10和ARF16的表达，在此期间表达增加了两倍。基因表达分析表明盐分胁迫下愈伤组织中的microRNA调节了盐反应基因家族。抗氧化酶的活性也在改变。MiR841被认为是抗氧化酶生物合成的正调节剂。拟南芥对愈伤组织中的盐胁迫有反应，可用于进一步研究胁迫耐受性的分子机制。