Multiple hormone analysis indicates involvement of jasmonate signalling in the early defence of potato to potato virus Y<sup>NTN</sup>

The involvement of plant hormones in the very early response of plants to virus infection was studied in potato plants (Solanum tuberosum L.) infected with potato virus YNTN (PVYNTN). Endogenous plant hormones and compounds mediating a stress response (JA-jasmonic acid, OPDA-12-oxo phytodienoic acid, SA-salicylic acid, IAA-indole-3-acetic acid, ABA-abscisic acid) were simultaneously quantified in susceptible cv. DĂŠsirĂŠe and resistant cv. SantĂŠ, one and three hours after inoculation. Of the hormones analysed, only the contents of endogenous JA and its precursor OPDA changed in a way that could be clearly connected with the early resistant response. In comparison to susceptible cultivar, a much more pronounced increase of JA was detected in virus-inoculated leaves of resistant cultivar at both time points. The same trend of changes was also observed with OPDA. However, there were no significant changes of JA and its precursor in upper intact systemic leaves and roots, at either time point. These findings implicate the jasmonate signalling pathway in a very early local but not systemic resistant defence of potato to PVYNTN.