关键词: 硒元素, 香蕉种质, 枯萎病, 抗氧化酶, 谷胱甘肽过氧化物酶

Abstract: Fusarium wilt disease, caused by the virulent tropical race 4 of Fusarium oxysporum f. sp. cubense (Foc TR4), poses a significant threat to the sustainable development of banana production industry. Selenium plays a crucial role in the prevention of Foc TR4 in the widely cultivated banana germplasm, Baxi Jiao. However, the underlying mechanisms remain unclear. The disease indices of five banana germplasms (Mbwazirume, Inkira, GCTCV-119, Gros Michel, and Banksii) were evaluated following treatment with 40 mg·L^-1 of selenium and inoculation with Foc TR4. We investigated the total selenium content, antioxidant enzyme activities \[superoxide dismutase (SOD), peroxidase (POD), polyphenol oxidase (PPO), catalase (CAT), glutathione peroxidase (GSH-Px)\], and glutathione (GSH) content in tissues at different time points to elucidate the mechanism of selenium-mediated resistance in bananas against Foc TR4. The results showed that selenium addition significantly reduced the disease index across the three germplasms (Mbwazirume, Inkira, and GCTCV-119), with controlling effects ranging from 41.7% to 62.6%. These germplasms had higher selenium content and enrichment coefficients in roots and leaves compared to germplasms with negligible control effects. Selenium enhanced GSH-Px enzyme activity in Mbwazirume and GCTCV-119, either maintaining or increasing GSH content, and contributed to the dynamic equilibrium between GSH-Px activity and GSH content. The POD activity in leaves, after pathogen inoculation, exhibited an initial increase, followed by a decrease, and then a resurgence, reaching peak values on 7th and 56th day after inoculation, respectively. Throughout this process, the peak values of POD activity remained within the normal range of 265.9 to 351.7 μmol·min^-1·g^-1. Furthermore, selenium significantly enhanced the PPO activity directly. This study elucidates the relationship between selenium enrichment ability and the preventive effects across different banana germplasms. The differential regulation of host antioxidant enzymes (GSH-Px, POD, and PPO) may serve as a mechanism by which selenium enhances resistance to Foc TR4. These findings provide a foundation for further exploration of the role of selenium in combating banana wilt disease.

Key words: selenium, banana germplasm, Fusarium wilt, antioxidant enzyme, GSHPx