28. アブシジン酸による植物の全身獲得抵抗性誘導の抑制効果

抄録

Probenazole (PBZ) and its active metabolite, 1,2-benzisothiazole-3(2H)-one 1,1-dioxide (BIT), induce PR genes expression and resistance against a broad range of pathogens in tobacco and Arabidopsis, by activating upstream of salicylic acid (SA) in SAR (systemic acquired resistance) signaling pathway. To investigate influence of environmental stress on SAR induction, we analyzed effects of abscisic acid (ABA) on SAR induction by BIT. In Arabidopsis, BIT treatment reduced the growth of a virulent bacterial pathogen Pseudomonas syringae pv. tomato DC3000 in leaves. However, ABA treatment reduced the BIT-induced disease resistance. ABA treatment suppressed BIT-induced PR genes expression and SA accumulation, indicating that ABA suppressed the induction of SAR. BTH (benzo(1,2,3)thiadiazole-7-carbothioic acid S-methyl ester), a SAR inducer, activates downstream of SA in SAR signaling pathway. ABA treatment also suppressed BTH-induced SAR in Arabidopsis. These results suggested that ABA downregulates SAR signaling pathway at upstream and downstream of SA accumulation.