Expression profiling of ABA pathway transcripts indicates crosstalk between abiotic and biotic stress responses in Arabidopsis.

Recent breakthrough on identification and characterization of PYR/PYLs as ABA receptors enables us to better understand the perception, signaling and transportation of ABA in plant. Based on publicly available microarray data, transcriptional levels of ABA signaling pathway core components were compared after stress and phytohormone treatments, including these involved in ABA metabolism, signal transduction, and catabolism. The results showed that both abiotic and biotic stress treatments increased the expression levels of ABA key metabolism and catabolism transcripts. The expression levels of PYR/PYLs were down-regulated and these of PP2Cs and ABFs were uniformly up-regulated after exogenous ABA application and under stress conditions. The results indicated that the increased ratio of PP2Cs:PYR/PYLs might be required for activation of the downstream ABA signal pathway under both abiotic and biotic stress conditions. We concluded that abiotic and biotic stress responses shared ABA signal pathway in Arabidopsis.