Bioinformatics analysis of BBX family genes and its response to UV-B in Arabidopsis thaliana

The B-box proteins (BBXs) are a family of zinc finger proteins containing one/two B-box domain(s), which play important roles in plant growth and development. Though the Arabidopsis thaliana BBX family genes have been identified and named, no systematic study has taken on BBX family genes involved in the regulation of UV-B induced photomorphogenesis in Arabidopsis thaliana. In our previous report, BBX24/STO was demonstrated to be a negative regulator in UV-B signaling pathway in Arabidopsis. In the present study, the total 32 BBX family genes from Arabidopsis were analyzed, including their structures, conserved domains, phylogenetic relationships, promoter cis-regulatory elements, expression patterns under UV-B radiation. The expression profile of GEO Datasets (GSE117199) related to UV-B in NCBI database was analyzed. qRT-PCR was used to validate the expression profile of several BBX genes in Arabidopsis treated with UV-B. The promoters of AtBBXs contained cis-acting elements that respond to light and hormones, including ethylene, auxin (IAA), abscisic acid (ABA), gibberellin (GA) and methyl jasmonate (MeJA). BBX24 and BBX25 were collinear blocks, suggesting that BBX25 may also be involved in UV-B signal transduction. Expression profile analysis and qRT-PCR validation showed that UV-B induced up-regulation of BBX1, BBX7, BBX20, BBX25 and BBX32, suggesting that AtBBXs were mainly involved in UV-B photomorphogenesis. It is predicted that BBX1, BBX7, BBX20 and BBX25 may be new members in response to UV-B signaling.