Polydimethylsiloxane-polymethacrylate block copolymers containing quaternary ammonium salts against Fusarium oxysporum f. sp. cubense race 4 in soil: Antifungal activities and pot experiments

摘要

Fusarium oxysporum f. sp. cubense race 4 (Foc4) has significant impacts on banana production. Foc4 conidia can survive for many years in the soil, making control difficult. Thus, the inhibition of the conidia that serve as a continual source of inoculum in soil should be an effective way to control banana Fusarium wilt. In this paper, we first investigated the activities of polydimethylsiloxane-polymethacrylate block copolymers containing quaternary ammonium salts (PDMS-b-QPDMAEMA, labeled Si(x)Q(5)) against Foc4 with microbroth dilution and toxicity plate assays. Then, the environmental behavior of these compounds, i.e., their adsorption and migration in soils, was further studied. Later, the effect and duration of Si(x)Q(5) on Foc4 in soil and the effects of Si(x)Q(5) on soil microbial diversity were evaluated. In addition, we conducted pot experiments to study the effect of Si(5)Q(5) on banana Fusarium wilt. The results showed that Si(x)Q(5) showed a good inhibitory effect on Foc4, was easily adsorbed by the soil and was relatively immobile in soil. The inhibitory effect of Si(x)Q(5) on Foc4 was maintained for 30 d under continual inoculation of Foc4 into the soil (Foc4 addition every 2 d), and Si(x)Q(5) remained active in the soil for 90 d with Foc4 addition every 10 d. Soil microbial population analysis revealed that the culturable total fungal and bacterial populations increased and the culturable actinobacterial population decreased Si(x)Q(5) with addition. Pot experiments showed that Si(5)Q(5) can reduce Foc4 infection in banana seedlings and does not harm banana seedlings. The stability and inhibitory effects on Foc4 demonstrate the potential application of Si(x)Q(5) in banana fields to prevent Foc4 conidial infection in the long term.