Salicylic Acid Protects Potato Plants-from Phytoplasma-associated Stress and Improves Tuber Photosynthate Assimilation

During a pathogen attack, cells triggers the overproduction of reactive oxygen species causing oxidative stress and physiological damage. Plants develop strategies using these reactive molecules for protection against pathogen attack. Phytoplasma are bacteria lacking cell walls that inhabit plant phloem and reduce yield, tuber quality, and commercial harvest value. Sprayed salicylic acid (SA) activated plant defense response against phytoplasma attack and reduced infection symptoms, favored photosynthate translocation, and improved tuber quality. Low levels of exogenous SA (0.001 mM) induced higher biological activity. Damage reduction was associated with high hydrogen peroxide and ascorbic acid contents together with reduction of peroxidase activity, suggesting an important SA role regulating these molecules counteracting pathogen effects.