Chitosan is a potent biopolymer having promising antimicrobial properties against phytopathogens. Recently, engineered nanomaterials (ENMs) have gained much attention due to their potential application in the plant disease management. In this study, we reported the green synthesis of chitosan-magnesium (CS-Mg) nanocomposite and its antimicrobial activity against two rice pathogens namely Acidovorax oryzae and Rhizoctonia solani for the first time. The green MgO nanoparticles synthesized by using a native Bacillus sp. strain RNT3, were used to fabricate CS-Mg nanocomposite utilizing one-pot synthesis method. The synthesis of CS-Mg nanocomposite was further confirmed by using UV–vis spectroscopy, whereas, FTIR and XRD analysis showed the capping of CS-Mg nanocomposites by different functional groups together with their crystalline structure, respectively. Besides, SEM and TEM images revealed the spherical shape along with the particles size ranging from 29 to 60 nm. Moreover, EDS analysis confirmed the elemental purity of nanocomposite. The CS-Mg nanocomposite showed remarkable antimicrobial activity against A. oryzae and R. solani and significantly inhibited the growth as compared to non-treated control. The ultrastructure studies showed damaged structure of cell wall and internal cellular organelles after treatment with 100 μg mL⁻¹ CS-Mg nanocomposite. The results of this study indicated that CS-Mg nanocomposite-based antimicrobial agents could be considered as promising nanopesticides against phytopathogens in plant disease management.

壳聚糖是一种有效的生物聚合物，对植物病原体具有良好的抗菌特性。最近，工程纳米材料（ENMs）由于其在植物病害管理中的潜在应用而备受关注。在这项研究中，我们首次报道了壳聚糖-镁（CS-Mg）纳米复合材料的绿色合成及其对两种水稻病原体，即米粉菌和茄根丝菌的抗菌活性。使用天然芽孢杆菌合成的绿色MgO纳米颗粒sp。菌株RNT3，用于通过一锅法合成CS-Mg纳米复合材料。紫外-可见光谱进一步证实了CS-Mg纳米复合材料的合成，而FTIR和XRD分析表明，CS-Mg纳米复合材料分别由不同的官能团及其晶体结构封端。此外，SEM和TEM图像显示出球形，粒径范围为29至60 nm。此外，EDS分析证实了纳米复合材料的元素纯度。CS-Mg纳米复合材料显示出对米曲霉和solani solani的显着抗菌活性与未处理的对照组相比，具有明显的抑制作用。超微结构研究显示，用100μgmL ^-1 CS-Mg纳米复合材料处理后，细胞壁和内部细胞器的结构受损。这项研究的结果表明，基于CS-Mg纳米复合材料的抗菌剂在植物病害管理中可以被视为对抗植物病原体的有前途的纳米农药。