Characterization of Protease Inhibitor Promoter from Black Gram (Vigna mungo L.) and gus Gene Expression in Transgenic Tobacco Plants

Abstract

Like other legumes, black gram is also known to be source of plant protease inhibitors. Plant protease inhibitors (PIs) are small proteins which represent a class of well studied compounds of plant defense genes and are abundant in storage organs such as seeds and tubers. The protease inhibitor proteins serve various functions in the growth and developmental processes. Like other legumes black gram (Vigna mungo L.) is also known to be a source of plant protease inhibitors and considered to be involved in insect tolerance. In this study, promoter sequence consisting of 0.75 fragments of a 52 upstream flanking region preceding a protease inhibitor gene of black gram was cloned from genomic clones and its sequence is characterized. The spatial and temporal control of the 0.75 fragment promoter sequence was also further investigated for its regulation on expression of the â-glucuronidase (gus) reporter gene in transgenic tobacco. Analysis of gus activities showed that the 0.75 kb flanking fragment of the protease inhibitor gene actually drives the gus reporter gene expression in ovary, pistil and seeds of tobacco. In another case, promoter sequence consisting of 1.3 kb fragment of a 52 flanking region of black gram protease inhibitor gene was isolated by Genome Walker strategy and promoter sequence was analyzed in-silico by PLACE and PlantCARE database.