Abstract
As a typical triazole fungicide, prothioconazole (Pro) has been used extensively due to its broad spectrum and high efficiency. However, as a racemic mixture of two enantiomers (R-Pro and S-Pro), the enantiomer-specific outcomes on the bioactivity have not been fully elucidated. Here, we investigate how chirality affects the activity and mechanism of action of Pro enantiomers on Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4), the notorious virulent strain causing Fusarium wilt of banana (FWB). The Pro enantiomers were evaluated in vivo and in vitro with the aid of three bioassay methods for their fungicidal activities against TR4 and the results suggested that the fungicidal activities of Pro enantiomers are stereoselective in a dose-dependent manner with R-Pro making a major contribution to the treatment outcomes. We found that R-Pro led to more severe morphological changes and impairment in membrane integrity than S-Pro. R-Pro also led to the increase of more MDA contents and the reduction of more SOD and CAT activities compared with the control and S-Pro groups. Furthermore, the expression of Cytochrome P450 14α-sterol demethylases (CYP51), the target for triazole fungicides, was significantly increased upon treatment with R-Pro rather than S-Pro, at both transcriptional and translational levels; so were the activities of the Cytochrome P450 enzymes. In addition, surface plasmon resonance (SPR) and molecular docking illuminated the stereoselective interactions between the Pro enantiomers and CYP51 of TR4 at the target site, and R-Pro showed a better binding affinity with CYP51 than S-Pro. These results suggested an enantioselective mechanism of Pro against TR4, which may rely on the enantioselective damages to the fungal cell membrane and the enantiospecific CYP51 binding affinity. Taken together, our study shed some light on the mechanisms underlying the differential activities of the Pro enantiomers against TR4 and demonstrated that Pro can be used as a potential candidate in the treatment of FWB.
Highlights
Fusarium wilt of banana (FWB), caused by soil-borne fungus Fusarium oxysporum f. sp.cubense (Foc) [1–3], led to the destruction of banana Gros Michel (Musa-AAA) and still poses as the greatest biotic challenge to the successor banana Cavendish [4]
These results suggested an enantioselective mechanism of Pro against tropical race 4 (TR4), which may rely on the enantioselective damages to the fungal cell membrane and the enantiospecific Cytochrome P450 14α-sterol demethylases (CYP51) binding affinity
Our study shows that both Pro enantiomers could exhibit fungicidal activities against
Summary
Fusarium wilt of banana (FWB), caused by soil-borne fungus Fusarium oxysporum f. sp.cubense (Foc) [1–3], led to the destruction of banana Gros Michel (Musa-AAA) and still poses as the greatest biotic challenge to the successor banana Cavendish [4]. Four physiological races of Foc have been identified far based on the different banana cultivars they can invade. Multiple approaches have been attempted, including breeding for resistant cultivars, to tackle this disease, but none of them were successful enough to be taken to the step in the field for effective control. Managing FWB is challenging due to Foc’s ability to survive in the soils for decades as chlamydospores [7]. Even though there are very few examples of clear progress for chemical control in the past 50 years, it is still an essential component of integrated management practices and has been proved to be effective in preventing the spread of Foc [9,10]. To expand the chemical control approach, more fungicides need to be screened, systematically investigated and employed for FWB management
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
