Genome-wide analysis of the CSN genes in land plants and their expression under various abiotic stress and phytohormone conditions in rice.

The CONSTITUTIVE PHOTOMORPHOGENIC9 (COP9) signalosome (CSN) is a multi-functional protein complex, which is involved in plant growth and abiotic stress response. However, the evolution and function of the CSN genes in land plants are still largely unclear. Here, we have identified 124 CSN genes and constructed phylogenetic trees of these CSN proteins to elucidate their feature and evolution in twelve land plants. Analysis of gene structure, protein property and protein motif composition shows the evolutional conservation and variation of the CSN proteins in land plants. These CSN genes might evolve through whole genome duplication (WGD)/segmental duplication (SD) and tandem duplication (TD). Analysis of promoter cis-elements shows that the CSN genes are implicated in diverse biological processes and different signaling pathways. RT-qPCR indicates that the transcript abundance of the OsCSN genes is up-regulated or down-regulated in response to abiotic stress and treatment with various hormones in rice. These results provide new insights into the CSN gene evolution and its possible function in land plants.