engleski

Effects of potato spindle tuber viroid infection on the levels of endogenous phytohormones and antioxidant enzyme activity in symptomless Solanum laxum plants

Viroids are plant pathogens characterized by a small (400 nt) single–stranded noncoding RNA genome. Potato spindle tuber viroid (PSTVd) mainly infects species belonging to the family Solanaceae with the potential to cause substantial damage to potato and tomato crops. In ornamental species including Solanum laxum, PSTVd infections are mostly symptomless, and therefore present the risk of propagating infected plants and spreading the disease to related crop plants. Latent infections are important in the control of plant diseases but also in breeding for resistance/tolerance to a pathogen. To learn more about the physiology of latent infections with viroids, changes in the endogenous phytohormones content and antioxidant enzyme activity in S. laxum infected by PSTVd were examined. Results showed that the endogenous jasmonic acid (JA) and castasterone (CS) significantly increased, while abscisic acid content significantly decreased in leaves of systemically infected plants compared to that of mock– inoculated control plants 18 wpi. PSTVd infection also enhanced the activity of ascorbate peroxidase and superoxide dismutase, while the activity of catalase remained steady. Results suggest the activation of the JA and CS signaling pathway in S. laxum as a part of defense response to PSTVd infection, although it seems that these changes have no effect on the onset of visible symptoms.

Solanum laxum, PSTVd, latent infection, phytohormones, antioxidant response

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