Disease development of several fungi on Arabidopsis can be reduced by treatment with methyl jasmonate

Pretreatment of Arabidopsis plants with gaseous methyl jasmonate (MeJA) cau sed efficient reduction of disease development by either the necrotrophic f ungi Alternaria brassicicola, Botryris cinerea or Plectosphaerella cucumeri na. Protection by gaseous MeJA was also observed on the salicylic acid (SA) -degrading transformant NahG and the ethylene non-responsive mutant ein2-1, but not on the jasmonate non-responsive mutant coil-1. In general, protect ion conferred by spraying with a MeJA solution was much lower compared to e xposure to gaseous MeJA. 2,6-Dichloroisonicotinic acid (INA), a compound th at activates SA- but not JA-dependent defence responses, failed to cause pr otection against either A. brassicicola r B. cinerea. On the other hand, IN A treatment was efficient in reducing disease development by P. cucumerina. (C) 2000 Editions scientifiques et medicales Elsevier SAS.