Salicylic acid is involved in the Nb-mediated defense responses to PVX in Solanum tuberosum

GERARDO SÁNCHEZ; NADIA GERHARDT; FLORENCIA SICILIANO; ADRIÁN VOJNOV; ISABELLE MALCUIT; MARÍA ROSA MARANO

MOLECULAR PLANT-MICROBE INTERACTIONS

AMER PHYTOPATHOLOGICAL SOC

Año: 2010 vol. 23 p. 394 - 405

0894-0282

To evaluate the role of salicylic acid (SA) in Nb-mediated hypersensitive resistance (HR) to Potato virus X (PVX) avirulent strain ROTH1 in Solanum tuberosum, we have constructed SA-deficient transgenic potato plant lines by over-expressing the bacterial enzyme salicylate hydroxylase (NahG), which degrades SA. Evaluation of these transgenic lines revealed hydrogen peroxide (H2O2) accumulation and spontaneous lesion formation in an age and light dependent manner. In concordance, NahG potato plants were more sensitive to treatment with methyl viologen, a reactive oxygen species (ROS) generating compound. In addition, when challenged with PVX-ROTH1, NahG transgenic lines showed a decreased disease-resistance response to infection and were unable to induce systemic acquired resistance. However, the avirulent viral effector, PVX 25-kDa protein, does induce expression of the pathogenesis related gene, PR-1a, in NahG potato plants. Taken together, our data indicate that SA is involved in local and systemic defense responses mediated by the Nb gene in Solanum tuberosum. This is the first report to show that basal levels of SA correlate with hypersensitive resistance to PVX.