Zinc oxide nanoparticles conferring resistance to Verticillium wilt in cotton
Lingxiao Zhu, Mingyu Hou, Hongchun Sun, Yongjiang Zhang, Ke Zhang, Zhiying Bai, Anchang Li, Hezhong Dong, Liantao Liu, Cundong Li
Abstract
Verticillium wilt , a serious fungal disease affecting cotton, is often referred to as the "cancer of cotton" due to its severe impact on cotton yield and quality. Zinc oxide nanoparticles (ZnO-NPs) are known to boost crop resistance to diseases, but their effectiveness against cotton's Verticillium wilt is not well understood. To address this gap, this study assessed the impacts of ZnO-NPs on cotton growth, physiological responses , and transcriptomic profiles following inoculation with Verticillium dahliae . The inhibitory effect of ZnO-NPs on Verticillium dahliae was concentration-dependent, and the inhibitory effect increased with increasing concentrations of ZnO-NPs, with 200 mg·L −1 being the most effectiver, reducing the disease index by 36.16 % compared to the control treatment (0 mg·L −1 ). Compared with no treatment, ZnO-NPs treatment reduced the levels of H 2 O 2 , O 2 - in roots and leaves, and malondialdehyde at 48 hours post-inoculation, and increased the activities of superoxide dismutase and catalase . The application of ZnO-NPs also increased the activities of defense-related enzymes in cotton, including phenylalanine ammonia lyase, polyphenol oxidase , and β-1,3-glucanase. The ZnO-NPs treatment resulted in a significant increase in lignin content and various hormone levels (auxin, salicylic acid, jasmonic acid , and melatonin) in the roots, while concurrently reducing ethylene levels. Transcriptomic analysis revealed that ZnO-NPs can enhance cotton’s resistance to Verticillium wilt by regulating genes involved in immune responses, antioxidant activities , plant-pathogen interactions, MAPK signaling, hormone signaling, and phenylpropanoid biosynthesis pathways, thereby increasing resistance to. These findings indicate that ZnO-NPs at the optimal concentration of 200 mg·L -1 could serve as an effective nanopesticides for managing Verticillium wilt in cotton.