Arabidopsis SIMILAR TO RCD-ONE genes are ubiquitous and respond to multiple abiotic stresses through diverse signaling pathways.

The SIMILAR TO RCD-ONE (SROs) have been characterized as a group of plant-specific proteins which play important functions in stress responses and development. Here, we analyze the expression profiles of six SRO genes under different stress treatments in Arabidopsis. Our results revealed that RCD1 play an essential role in plant responses to various environmental stresses. SRO1 has partially overlapping functions with RCD1 in plant response to HgCl2 and H2O2 stress. Analysis of the transcriptional expression of SROs indicated that both of the RCD1 and SRO1 transcripts were up-regulated by HgCl2 and light, not by other stresses, and that of SRO5 was induced by salt. Expression of SRO3 and SRO4 were not influenced by stresses. The different effects of these stresses on the expression of the SRO genes indicate that the SRO family is regulated by multiple signaling pathways. Sequence analyses of the SRO proteins implicate a highly preserved protein structure and are specific to plants, which might have implications for functional conservation. The ubiquitous expression and nuclear localization of SRO family suggested that their function might be related to transcription factor regulation and complex formation. Taken together, SRO family is critical for proper plant development and multiple stress responses.