A ramie (Boehmeria nivea) bZIP transcription factor BnbZIP3 positively regulates drought, salinity and heavy metal tolerance

摘要

bZIP genes play important roles in the regulation of many developmental and physiological processes and adaptive responses to the environment in plants. In the present study, a novel bZIP gene, designated as BnbZIP3 (Genbank accession number: KP462877), was cloned from ramie plants based on the sequence of Unigene6582 fragment in ramie transcriptome using rapid amplification of cDNA ends (RACE) technique and real-time PCR. Results indicated that BnbZIP3 had a 999-bp open reading frame, encoding a 332 amino acid protein that containing a characteristic bZIP domain, and shared high sequence identities with bZIP factors from other plants. Translational fusion of BnbZIP3 with EGFP showed subcellular localization of the protein in nucleus. Transcripts of BnbZIP3 were found in different tissues of ramie plants. Expression of BnbZIP3 was induced by drought, high salinity and ABA treatments. The promoter of BnbZIP3 contained many cis-acting elements involved in multiple stress responses. Overexpression of BnbZIP3 in transgenic Arabidopsis plants inhibited the growth of roots under normal growth conditions, whereas it improved the growth of roots under dehydration, salinity and heavy metal Cd stress, and increased germination of seeds under drought conditions. Thus, BnbZIP3 may positively regulate stress tolerance and be used to engineer enhanced drought, salt and heavy metal tolerance of ramie varieties or other industrial crops.