Cloning of MYB transcription factor gene(GbMYB5) promoter from Gossypium barbadense L. and functional expression characterization in transgenic Arabidopsis thaliana

GbMYB5 gene of Gossypium barbadense L.belongs to the big transcript factor family of MYB genes,which may participate in a series of gene expression related to biotic and abiotic stresses.To further study the function of GbMYB5 gene,a 2.2 kb promoter sequence from G.barbadense L.was isolated by PCR,which belongs to upstream DNA fragment of GbMYB5 gene.Sequence analysis revealed that the sequence was the promoter of GbMYB5 gene,and contained a variety of cis-elements responding to light signaling pathways(Box-I,Box-4,I-box,G-Box),phytohormones(ABA,GA,ethylene),stress(heat,drought) and cis-acting element involved in salicylic acid responsiveness(TCA-element).The plant expression vector with GUS reporter gene(pGbMYB5-GUS) driven by GbMYB5 promoter was constructed from PBI101 by substituting the CaMV35S promoter,and the vector containing GbMYB5 promoter was transferred into Arabidopsis thaliana using Floral-dip method.Histochemical staining revealed that GUS gene was exclusively expressed in root,blade tip,and apical meristem in transgenic Arabidopsis thaliana,which indicated GbMYB5 promoter was a tissue-specific promoter.