Updated project metadata. Salt stress is a major environmental factor limiting plant growth and development. Previous studies have indicated that the steroidal hormones—brassinosteroids (BRs) are important regulators of plant responses to salt stress. We found that bes1-D, a gain-of-function mutant of the BR-regulated transcriptional factor BES1 (AT1G19350) in Arabidopsis showed better salt tolerance than the wild-type plant (Col-0). Label-free based LC-MS/MS and proteomic analyses were performed to investigate protein expression in bes1-D and wild-type in response to salt stress.