In vitro effects of potato glycoalkaloids on plant-pathogens, beneficial microbes, and Arabidopsis thaliana.

Potato glycoalkaloids (PGAs), α-solanine and α-chaconine, are secondary metabolites related to plant defense. Highly concentrated in the upper part of potato plants, they exhibit antimicrobial properties. Seeking more sustainable crop protection strategies, this study investigates the effects of PGAs on plant pathogens and beneficial organisms. These organisms were exposed to different PGA concentrations (0.98 to 250 ppm), with evaluations focusing on developmental and survival metrics. Key findings highlight α-chaconine as the more potent compound, causing significantly stronger adverse effects across tested organisms. E.g., α-chaconine (≤ 25 ppm) reduced nematode mobility by 43%, host attraction by > 45%, and infection rates by 63%. At 250 ppm, α-solanine moderately reduced mycelial growth, while α-chaconine reduced it by 78%. Crucially, beneficial organisms experienced minimal growth impairment (≤ 19%) even at the highest concentration (250 ppm). Arabidopsis thaliana seedling development was impaired by both PGAs, and seedlings exposed to these compounds exhibited a strong, transient oxidative burst, indicating direct stress activation. Pretreatment with PGAs did not induce priming effects but even decreased subsequent elicitor-induced responses. The selective toxicity against pathogens, coupled with minimal impact on beneficial species, positions PGAs, particularly α-chaconine, as promising starting points for sustainable crop protection strategies.