Salicylic acid enhances the synthesis of TobaccoNecrosis Virus (TNV) and inhibits formation of antiviral factors in Chenopodium amaranticolorplants

Salicylic acid (SA) is often regarded as a signal molecule involved in systemic acquired resistance (SAR) against plant virus infections. When infiltrated into Chenopodium amaranticolor leaves 12 h prior to inoculation with tobacco necrosis virus (TNV), it caused an increase in virus synthesis. It seems therefore, that in our system, SA is involved in a mechanism of acquired susceptibility rather than acquired resistance to TNV. These results are different from all others previously reported for virus infection and question the proposed SA general role of signal molecule triggering plant defence mechanism against pathogens. Our is not the first evidence of SA-suppressed resistance in plants. This together with previous researches where SA neither induced PR-protein formation nor induced acquired resistance to virus infections, support the idea that plant SAR is a complex phenomenon, probably depending on various mechanisms. One of them is the impaired formation of antiviral factors in the interaction system C. amaranticolor/TNV.