Drought is a global issue causing severe reductions in crop yields. The use of nanobiotechnology to increase plant resistance to drought is widely reported. However, the mechanisms underlying nanomaterial improvement of crop drought tolerance are not well understood. Herein, we reported that poly(acrylic) acid coated manganese oxide (Mn₃O₄) nanoparticles (PMO, 5.43 nm, −31.6 mV) increase cotton fresh weight (74.9%) under drought stress relative to controls by catalytically scavenging ROS and modulating stomatal aperture. PMO treated cotton leaves showed significantly lower ROS levels (60–70%) determined by confocal microscopy and biochemical and histochemical staining analysis. Also, plants exposed to PMO experienced less oxidative damage than controls under drought, as indicated by their lower malondialdehyde (MDA) content (2.02 ± 0.15 μmol L⁻¹ vs. 3.25 ± 0.27 μmol L⁻¹) and electrolyte leakage rate (31.13% ± 5.51 vs. 64.83% ± 4.29). PMO treated cotton plants also maintained stomatal aperture and had higher photosynthetic performance (160%) under drought stress. Furthermore, we set up a portable monitoring system with low cost which can allow the real-time imaging of stomatal aperture and chlorophyll fluorescence in plants treated with nanomaterials. Overall, our results suggested that PMO could be a biocompatible and scalable tool for improving crop drought tolerance.

中文翻译：

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Mn3O4 纳米颗粒维持 ROS 稳态以调节气孔孔径以提高棉花的耐旱性


干旱是一个全球性问题，导致农作物产量严重下降。使用纳米生物技术提高植物对干旱的抵抗力已被广泛报道。然而，纳米材料提高作物耐旱性的潜在机制尚不清楚。在此，我们报道了聚（丙烯酸）涂层的氧化锰 （Mn₃O₄） 纳米颗粒 （PMO， 5.43 nm， -31.6 mV） 在干旱胁迫下通过催化清除 ROS 和调节气孔孔径增加了棉花鲜重 （74.9%）。通过共聚焦显微镜和生化和组织化学染色分析确定 PMO 处理的棉叶显示出显着较低的 ROS 水平 （60-70%）。此外，在干旱下，暴露于 PMO 的植物比对照组经历的氧化损伤更少，如它们较低的丙二醛 （MDA） 含量 （2.02 ± 0.15 μmol ^L-1vs. 3.25 ± 0.27 μmol ^L-1） 和电解质泄漏率 （31.13% ± 5.51 vs. 64.83% ± 4.29） 所示。PMO 处理的棉花植株在干旱胁迫下也保持气孔孔径，并具有更高的光合性能 （160%）。此外，我们建立了一个低成本的便携式监测系统，可以对用纳米材料处理的植物中的气孔孔径和叶绿素荧光进行实时成像。总体而言，我们的结果表明 PMO 可以成为提高作物耐旱性的生物相容性和可扩展工具。