Functional characterization of the rice root Germin-like protein gene-1 (OsRGLP1) promoter in Nicotiana tabacum.

Germin (GER) and germin-like protein (GLP) genes play a very important role against various stresses. Promoter analysis provide significant insight into gene's function and regulation. Presently, upstream region (1228 bp) of the OsRGLP1 gene was functionally characterized via heterologous expression. It was fused with the Glucuronidase (GUS) reporter gene and the expression cassette was used to transform Nicotiana tabacum using Agrobacterium-mediated transformation. Transgenic plants were examined via quantitative real-time PCR (qPCR) to analyze its role in wounding, salinity, drought, abscisic acid (ABA) and circadian rhythm. OsRGLP1 was highly induced by ABA and drought by showing 28- and 25-fold changes in GUS mRNA level respectively as compared to wounding (fourfold change) and salinity (threefold change). However, no activity was observed in circadian rhythm. Histochemically, strong GUS activity was observed in leaf veins, midrib, epidermal hair, stomata guard cells, stem cortex, root hairs, xylem and phloem and at cellular level in cell wall, cytoplasm and its periphery. OsRGLP1 promoter can be used to develop agronomically important transgenic plants in future food program.