TMT-Based Comparative Peptidomics Analysis of Rice Seedlings under Salt Stress: An Accessible Method to Explore Plant Stress-Tolerance Processing.

Rice ( L.) is an important staple crop, particularly in Asia, and abiotic stress conditions easily reduce its yields. Salt stress is one of the critical factors affecting rice growth and yield. In this study, a tandem mass tag (TMT)-based comparative peptidomics analysis of rice seedlings under salt stress was conducted. Rice seedlings were exposed to 50 and 150 mM NaCl for 24 and 72 h, respectively, and the root and shoot tissues of different treatment groups were collected separately for peptidomics analysis. A total of 911 and 1263 nonredundant peptides were identified in two pooled shoot tissue samples, while there were 770 and 672 nonredundant peptides in two pooled root tissue samples, respectively. Compared with the control groups, dozens to hundreds of differentially expressed peptides (DEPs) were characterized in all treatment groups. To explore the potential functions of these DEPs, we analyzed the basic characteristics of DEPs and further analyzed the annotated Gene Ontology terms according to their precursor proteins. Several DEP precursor proteins were closely related to the response to salt stress, and some were derived from the functional domains of their corresponding precursors. The germination rate and cotyledon greening rate of transgenic expressing two DEPs, OsSTPE2 and OsSTPE3, were significantly enhanced under salt stress. The described workflow enables the discovery of a functional pipeline for the characterization of the plant peptidome and reveals two new plant peptides that confer salinity tolerance to plants. Data are available via ProteomeXchange with identifier PXD037574.