Physiological characterization of asparagus decline syndrome

Abstract Background and aims Asparagus Decline Syndrome (ADS) threatens the sustainability and productivity of asparagus ( Asparagus officinalis L.) cultivation. This study aimed to characterize the physiological responses of asparagus plants to ADS, focusing on oxidative metabolism, hormonal regulation, and phenolic compounds profiles to understand the underlying mechanisms and inform management strategies. Methods A field trial was conducted in the south of Spain comparing asparagus plants grown in soil from a plot previously affected by the ADS with a control soil (not affected). The key parameters assessed included biomass and oxidative stress indicators, phytohormone and phenolic compounds profiles in the root and shoot, and the soil phenolic compounds. Results ADS-affected plants exhibited lower fresh and dry weight and volume, and elevated oxidative stress, as evidenced by increased malondialdehyde (MDA) and H 2 O 2 levels, along with enhanced activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX). Hormonal analysis revealed higher concentrations of abscisic acid (ABA) and jasmonic acid, alongside a concurrent reduction in indoleacetic, suggesting a stress-induced response likely contributing to growth inhibition. Furthermore, the depletion of caffeic acid in roots, alterations in flavonoid profiles in shoot tissues, and increased PPO activity were observed, potentially worsening oxidative stress and depleting antioxidant reserves. Finally, ferulic acid derivatives in the soil were identified as potential allelopathic compounds. Conclusion These findings highlight the complexity of ADS and underscore the importance of integrated management strategies, including soil health management, resistant varieties selection, and targeted modulation of plant physiological responses to mitigate the impacts of ADS on asparagus production.