Induction of Pisatin Synthesis in Pea with Salicylic Acid or Inoculation with Powdery Mildew

摘要

Accumulation of phytoalexin is a host defense mechanism against invading pathogens. It is not clear if phytoalexins can be produced in sufficient quantity by exogenous treatment of plants with elicitors. Salicylic acid (SA) was applied at 1, or 3 or 5mM concentrations to eight-week-old pea plants to determine if it could induce the synthesis of pisatin, the pea phytoalexin. Other plants were inoculated with Erysiphe polygoni. There was an increase in the phenylalanine ammo-nia-lyase activity and phenolic contents in plants treated with SA and spores of E. polygoni. Plants treated with 1 and 3 mM SA showed minor variations in phenylalanine ammonia-lyase activity and phenolic contents and did not accumulate detectable amounts of pisatin. Treatment with 5 mM SA increased pisatin and phenolic contents in susceptible pea plants.