Synergy of cystamine and pyraclostrobin against Fusarium graminearum involves membrane permeability mitigation and autophagy enhancement

Antifungal Activity of Novel Isoindoline-2-Yl Putrescines as Potential Autophagy-Activated Fungicide

The exacerbation of plant fungal diseases necessitates the development of new fungicides to prevent outbreaks. In this study, five novel isoindoline-2-yl putrescines (ISPs) were synthesized, and their synthetic procedures and gram-scale preparation were explored. When tested at 50 μg mL-1, ISPs did not significantly inhibit mycelial growth on agar plates. However, at 100 μg mL-1, they demonstrated remarkable in vivo efficacy in mitigating Botrytis cinerea infection, especially ISP3 showed curative and protective activities of 91.9 % and 92.6 %, respectively. Moreover, ISP3 also effectively halted lesion expansion of gray mold, Sclerotic rot, and Fusarium scabs, while inducing excessive malformed top mycelial branches of B. cinerea and Sclerotinia sclerotiorum, suppressing sclerotia formation in S. sclerotiorum, and triggering autophagic vacuolization with numerous autophagosomes in the mycelia of these fungi. Molecular docking revealed that ISP3 effectively bound to the active site of BcAtg3, forming hydrogen bonds with Ser279, Gly343, Asp370, and Asp13, along with establishing a stable salt bridge with Asp13. Furthermore, ISP3 possessed favorable ADMET properties. These findings highlight ISP3 as a promising antifungal candidate through autophagy activation.

Ascendancy of pyraclostrobin nanocapsule formulation against Rhizoctonia solani: From a perspective of fungus

High-performance pesticide formulations are essential for sustainable agriculture. Among these, nano-pesticides exhibit great advantages in pest control because of their unique size effects. However, the direct effects of nano-formulation fungicides on fungal pathogens remain largely unexplored. In this study, three qualified formulations, suspension concentrate (SC), microcapsules (CS), and nanocapsules (NCS) of pyraclostrobin (PYR) were prepared and utilized to reveal their biocontrol activities against Rhizoctonia solani. Among these three formulations, NCS exhibited notable biocontrol efficacy against R. solani exemplified by an EC50 of 0.319 mg/L for mycelia, distortion of mycelia and abnormalities in cell ultrastructure. Moreover, NCS displayed excellent internalization within R. solani mycelia, contributing to severe damage to cell membrane permeability. Importantly, an equivalent quantity of NCS-PYR showed potent inhibitory effects on the target pathogen, as indicated by reduced adenosine triphosphate (ATP) content and mitochondrial Complex III activity. The NCS consistently exhibited superior in vivo protective and curative activities against R. solani compared to those of CS and SC in rice and faba bean. In summary, we uncovered the strength of rapid efficacy and biocontrol activity of NCS against R. solani and elucidated the advantages of NCS-PYR from the perspective of the target pathogen in agriculture.