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Activity characterization of the plantain promoter from the heavy metal-associated isoprenylated plant gene (MabHIPP) using the luciferase reporter gene

Abstract:

Banana and plantain crops may be subjected to different abiotic stress factors such as temperature, salinity and presence of heavy metals. Genetic engineering has been a valuable tool to accelerate modifications in plants by expressing genes to improve tolerance to different abiotic stress. Promoters have a fundamental role to drive the specific expression of useful genes in genetically modified plants. For promoter activity characterization, fusion with reporter genes are often used. The American firefly luciferase reporter gene system (LUC) could be used to characterize the promoter activity in vivo and with high sensitivity when compared to other reporter genes including β-glucuronidase (GUS) and Green fluorescent protein (GFP). In this study, activity of the heavy metal-associated isoprenylated plant protein (HIPP) promoter, originally discovered in a T-DNA tagging approached in plantain, was tested in the banana ‘Williams’ (genotype AAA) by Agrobacterium-mediated transformation of in vitro plants. A 625 bp promoter region was fused to the luc2 reporter gene in a pCAMBIA 1301-GUS less vector backbone. In silico promoter analysis revealed candidate cis-acting elements and a TATA box. Luciferase activity was up-regulated after 6 h of 60 μM of cadmium application in banana in vitro plants, indicating an increase in promoter activity. The luciferase reporter gene proved to be a useful tool to evaluate differential promoter activity after metal application in plants in vivo.