Potato glycoalkaloids affect the respiration and reactive oxygen species metabolism of Fusarium solani

Abstract:

[Background] Fusarium solani, a ubiquitous pathogenic fungus, can cause a variety of soil borne diseases of plants and is one of the main pathogens causing root rot of Lycium barbarum. Potato glycoalkaloids (PGAs) have strong activity against F. solani and their source plants are widely cultivated with low cost. [Objective] To observe the effects of PGAs on the respiration and reactive oxygen species (ROS) metabolism of F. solani and decipher the possible antibacterial mechanism from the perspective of energy metabolism. [Methods] PGAs were extracted from potato buds by acetic acid and ammonia precipitation method, and F. solani was selected as the test pathogen. The inhibitory effect of PGAs on the mycelial growth of F. solani in PDA and PDB was investigated and the concentration for 50% of maximum effect (EC₅₀) was determined. The effect of PGAs on the respiration of F. solani was detected by an oxygen electrode. The effects of PGAs on the antioxidant enzyme system, ROS, and the metabolite malondialdehyde (MDA) of F. solani were studied in PDB. [Results] The PGA treatment decreased the mycelial respiration rate in a concentration and time-dependent manner and increased the content of intracellular hydrogen peroxide (H₂O₂) and superoxide anion (O₂⁻) (P<0.05). Furthermore, the treatment caused the imbalance of the peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD) system, aggravated the membrane lipid peroxidation, and increased MDA content. Transmission electron microscopy results showed that the PGA treatment broke the mitochondrial membrane, caused the loss of mitochondrial contents, and destroyed the mitochondria of F. solani. [Conclusion] PGAs inhibit the respiration and reactive oxygen species metabolism, destroy mitochondria, the main organelle of the energy metabolism pathway, and finally inhibit the mycelial growth of F. solani.