High resolution profiling of gene expression during probenazole (PBZ) treatment in Arabidopsis

Leaf senescence is a developmentally programmed event, which is also regulated by several phytohormones such as SA. SA has been shown to regulate the expression of many genes during leaf senescence, the fact that the mutants defective in SA biosynthesis and signaling have negligible senescence-related phenotypes makes it difficult to evaluate the exact role of SA in regulating leaf senescence. We have previously shown that probenazole (PBZ) is able to induce endogenous SA biosynthesis when applied by root drenching. We also detected an accelerated leaf yellowing phenotype about two weeks after PBZ treatment. Analysis of PBZ response genes identifies several MAPKs genes may be involved in SA induced senescence signaling pathway. We used microarrays to detail the global programme of gene expression underlying probenazole (PBZ) treatment in Arabidopsis and identified distinct classes of MAPKs genes during this process. We used 5 week old Arabidopsis to conduct 0.5 mM probenazole (PBZ) root drenching to induce endogenous SA biosynthesis. The 5th through the 8th true leaves were chosen for physiological and molecular analyses because they exhibited the most significant leaf yellowing phenotypes. We used two biological replicates for each time points: before PBZ treatment (PBZ_T0-1, PBZ_T0-2) and after 72h PBZ treatment (PBZ_T72-1, PBZ_T72-2), respectively.