Genome-wide identification and expression profiling of genes encoding universal stress proteins (USP) identify multi-stress responsive USP genes in Arabidopsis thaliana

Universal stress proteins (USPs) are stress-responsive proteins conserved among various organisms, including bacteria, plants and metazoans. However, in plants, the function of most of the USPs remains largely unknown. In the present study, we have identified 53 USP domain-containing proteins encoded by 41 genes in the Arabidopsis genome. Based on the presence of additional protein kinase or tyrosine kinase domain, the nomenclature has been provided to these proteins. Comprehensive in silico expression profiling of AtUSPs under various developmental stages revealed that most of the genes are expressed in a tissue-specific manner. Under abiotic stresses, AtUSP9 and AtUSP12 were identified as multi-stress responsive in both shoot and root tissues. Interestingly, AtUSP9 was also induced under various pathogens and elicitor treatments. The expression analysis of USP genes under abiotic stresses using qRT-PCR correlated well with in silico expression analysis. Thus, the present study provides a blueprint for the functional characterization of AtUSPs to ascertain their role under stress conditions. Moreover, AtUSP9 and AtUSP12 may also be used to engineer plants with improved tolerance against multiple stresses.