Abstract
Systemic acquired resistance (SAR) is one of plant defense system, following salicylic acid (SA) accumulation and SAR marker genes expression. To investigate the influences of environmental stress on SAR induction, we analyzed effects of abscisic acid (ABA) on SAR. In this study, we used 1,2-benzisothiazole-3(2H)-one 1,1-dioxide (BIT), for SAR induction. BIT activate upstream of SA in SAR. ABA treatment suppressed BIT-induced PR genes expression and SA accumulation, indicating that ABA suppressed the induction of SAR by BIT. 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. Furthermore, environmental stress such as osmotic stress induced by mannitol suppressed the induction of SAR.
