Arabidopsis thaliana AtTFIIB1 gene displays alternative splicing under different abiotic stresses

In Arabidopsis, there are 14 TFIIB-like proteins that have been phylogenetically categorized into the TFIIB, BRF, and Rrn7/TAF1B/MEE12 subfamilies. The TFIIB transcription factor (TF) subfamily plays a key role in the regulation of gene expression in eukaryotes. To identify the expression patterns of some members of the TFIIB and BRF subfamilies in A. thaliana, different approaches were carried out to determine the possible functions of some of these transcription factors. Through an in silico analysis, we identified possible cis-acting regulatory elements in the promoter regions that drive the expression of transcription factors, as well as we evaluated their expression by means of real-time qPCR, at different growth stages and under various stress conditions. Cis-acting elements analysis showed that general transcription factors possess stress-responsive elements such as W-Box (TTGACC/T type binding WRKY TFs), ARF1 (auxin response), MYB binding site promoter (auxin response and elicitors), RAV1-A (response to dehydration and salinity), and DRE elements (dehydration response) among others. The experimental results showed differential expression of TFIIB1 and TFIIB. In addition, we demonstrate that in stress conditions a transcript of the TFIIB1 factor is generated as an alternative splicing product by retention of the third intron, where a premature termination codon is found. This is the first report of an alternative splicing event in a general transcription factor related to RNA pol II, which is synthesized when the plant is under abiotic stresses such as heat, dehydration, and salinity.

Automated summary

This study analyzed the expression patterns of TFIIB and BRF subfamilies in Arabidopsis, identifying a novel alternative splicing event of the TFIIB1 factor under stress conditions. Through in silico analysis and real-time qPCR, the study provided insights into the regulatory elements and differential expression of these transcription factors in response to various stressors.