CHETAN CHAUHAN, DARSHNA CHAUDHARY AND SANDIP DAS
Centre for Biotechnology, Maharshi Dayanand University, Rohtak-124 001 (Haryana), India
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(Received : April 1, 2019; Accepted : June 12, 2019)
Promoter as is elements are necessary to specify expression domains, and is responsible for transcriptional regulation of gene expression. MIRNA genes are important developmental and adaptive regulators and information on transcriptional regulation of MIR159b driving its spatio-temporal expression pattern in Brassica juncea var. Varuna is lacking. Therefore, the promoter of MIR159b was isolated from B. juncea var. Varuna for sequence and functional analysis. The promoter Bj-p-MIR159b :: GUS reporter construct was used to generate transgenic lines in B. juncea var. Varuna genetic background. Pair-wise sequence alignment of promoter sequences associated with homologs of MIR159b from B. juncea and B. rapa showed high level of divergence. Motif prediction and analysis revealed MYB binding site (MBS; TAACTG) and Low Temperature Responsive Element (LTRE; CCGAAA) were overrepresented in the promoter sequence. Transgenics of B. juncea showed reporter activity only in the callus. The reporter activity was lost in the emerging leaf buds or in the mature leaf in the plantlet. The present study will help to understand the regulation of MIR159b during differentiation process and stress response.
Key words :MIR159b promoter, leaf, callus, transgenic, GUS transcriptional reporter