Isolation, expression and function analysis of a bZIP transcription factor IbbZIP37 in sweetpotato (Ipomoea batatas L. [Lam])

Abstract

bZIP transcription factor play an important regulatory role in the response to multiple abiotic stresses. However, our knowledge of the stress tolerance functions of bZIP family genes in sweetpotato (Ipomoea batatas [L.] Lam) remains limited. In the present study, we isolated and functionally characterized an IbbZIP37 gene encoding an abiotic stress-inducible bZIP group A transcription factor. Sequence analysis showed that the IbbZIP37 contained a typical bZIP domain and five conserved Ser/Thr kinase phosphorylation sites (RXXS/T). The IbbZIP37 protein was localized in the nucleus and possessed transcriptional activation activity. The results of electrophoretic mobility shift assays indicated that IbbZIP37 can bind to the ABRE cis-element, not do to DRE cis-element in vitro. The IbbZIP37 gene showed the highest level of constitutive expression in root, especially in fibrous root and storage root body. Gene expression was induced by ABA and several environmental stresses including drought, salt and heat shock. Our results suggest that IbbZIP37 is a positive transcription regulator of the abiotic stresses response, which can be used as an excellent candidate for improving the stress tolerance of different crop plants.