LAUSR

Lead (Pb) is a heavy metal with high toxicity to plants. Root is the major organ to respond to Pb stress. However, little is known about how plant roots perceive Pb stress signaling. Here, we describe the transcriptome of Arabidopsis root tips under Pb stress using the RNA-seq assay. A total of 703 differentially expressed genes (DEGs) were identified and expressed at every time points. Some early-responsive DEGs (1 h) were predicted to be negatively involved in cell elongation and cell expansion, while some late-responsive DEGs (24 h) positively participated in defense of oxidative stress. Hydrogen peroxide (H 2 O 2 ) and superoxide (O 2 − ) were increased significantly in root tips under Pb stress. Cell wall extension related gene XYLOGLUCAN ENDOTRANSGLUCOSYLASE/HYDROLASE 18 ( XTH18 ) was induced in root tips, and xth18 showed reduced root growth inhibition by Pb stress. Our results revealed the potential mechanism of root growth inhibition by Pb stress and shed light for the further study.