Isolation and characterization of an AP2/ERF-RAV transcription factor BnaRAV-1-HY15 in Brassica napus L. HuYou15

Transcriptional regulation is thought to be important for stress tolerance and response of transcription factors. RAV subfamily transcription factor contains an AP2- and B3-DNA binding domain, which belongs to the AP2/ERF family. It encodes transcriptional regulators with a variety of functions involved in the developmental and physiological processes in plants. Here, a RAV-like gene, BnaRAV-1-HY15, was isolated from Brassica napus L. cv HuYou15. Sequence homology analysis revealed that the BnaRAV-1-HY15 factor belongs to the RAV subfamily of the AP2/ERF family, and it shares high identity with the AtRAV2 of Arabidopsis. Sequence and three-dimensional structural analyses revealed that BnaRAV-1-HY15 contains two distinct DNA-binding domains, one AP2 domain together with one B3 domain. The AP2 domain composed of 54 amino acids and present in N-terminal region. In addition to AP2 domain, 117 amino acids show significant sequence similarity to the B3 domain present in C-terminal region. Semi-quantitative RT-PCR analysis indicated that the BnaRAV-1-HY15 gene is induced by cold, NaCl and PEG treatments. Under ABA stress, the expression of BnaRAV-1-HY15 gene was not detected. The gene expression was also not traceable from the tissues of pod, bud, petal, leaf, stem and root of normally grown B. napus L. HuYou15 plant at the period of flowering and seed development.