DYNAMICS OF OsRGLP1 GENE DURING FUNGAL EXPOSURE IN TRANSGENIC POTATO

Abstract

Germin like proteins (GLPs) are large group of related and ubiquitous plant proteins. These proteins are considered to be involved in most of the processes important for the development of plant and defense mechanism. Although multiple copies of this gene family have been reported in a number of species (wheat, barley, rice, soybean, mosses and liverwort), even then the up-regulated expression of GLP transgenes has demonstrated additional defense capabilities. Due to reported role of GLPs in conferring fungal resistance, there is a need to explore their antifungal activity. For this purpose potato was selected as experimental material. It is a vegetable crop and produces, on average, additional food energy and protein than cereals. Potato with immense nutritive value, large yield, and significant cash return to farmers, has become a major crop for both farmers and consumers in Pakistan. Potato is susceptible to many kinds of diseases, especially to fungal pathogens, therefore genetic engineering of potato for disease resistance is an important strategy study and apply disease resistance. GM technology can be an effective tool for crop improvement. The transgenic approach was pursued to introduce rice (Oryza sativa) germin like protein gene OsRGLP1 using two recombinant vectors pC:OsRGLP1 and pG:OsGLP1 via Agrobacterium mediated transformation. Confirmation of presence of gene was carried out by polymerase chain reaction (PCR). One-step reverse transcriptase PCR was used for transcriptional analysis and expression was quantified in real time in all PCR positive putative transgenic lines. Functional status of transgene was studied in selected high expression lines from two vectors. It was observed that OsRGLP1 possesses super oxide dismutase activity and it is heat resistant and is sensitive to H2O2. These characteristics make it a Fe like SOD. A high H2O2 level was detected in transgenic lines. Fungal assay with Fusarium oxysporum f. sp. tuberosi showed xvi enhanced foliar resistance in transgenic lines in comparison to untransformed control plants. OsRGLP1 may be used as source for nonspecific fungal resistance in plants and the antioxidant activity of heat resistant SOD may be explored for abiotic stress tolerance.