Potato (Solanum tuberosum L.) is a solanaceous food crop having promising potential to compromise the on-going threats of food security in Pakistan. Potato is progressively cultivated as a cash crop that yields a good economic return to the farmers. Unfortunately, the crop suffers from multiple biotic and abiotic stresses which results in substantial production losses. The current PhD study was aimed at potato improvement in terms of multiple viral resistance and controlling the problem of cold induced sweetening (CIS) in stored tubers. For achieving the desired goals, RNA interference (RNAi) based methodology was used to develop transgenic potatoes conferring viral/CIS resistance. The first axis of research was centered to the approximation of disease/viral prevalence in major potato growing areas of Punjab province, which covers up to 85% of total potato production in Pakistan. Serological screening using enzyme-linked immunosorbent assay (ELISA) was performed for the detection of commonly prevailing RNA viruses; Potato virus X (PVX), Potato virus Y (PVY), Potato virus S (PVS), Potato leaf roll virus (PLRV), Potato virus M (PVM) and Potato virus A (PVA) in two of commercially grown cultivars, Cardinal and Desiree. The screening results confirmed the prevalence of all suspected viruses in both cultivars but with uneven distribution across different growing localities with infection levels of up to 50% in some regions. Mixed infections cases were also considerable amongst different viruses and were co-related with virus titre accumulation and disease severity index. The results of screening assays demonstrated a significant impact of synergistic interactions amongst different potato viruses on crop yield in terms of profound disease expressions. During field surveys, some samples showed severe leaf curl symptoms (phenotypically in line with begomoviral infection) especially at field corners where cotton was grown in the next field. Suspected samples were checked through molecular techniques and the results confirmed the presence of Tomato leaf curl New Delhi virus (ToLCNDV) and associated Tomato leaf curl betasatellites (ToLCB). To our knowledge, this is the first report of ToLCNDV infecting potato crop in Pakistan. The second part of the research was concerned with generating broad-spectrum viral resistance. For this purpose, most conserved genomic regions of PVX, PVY, PVS, PLRV and ToLCNDV were isolated and synthetically synthesized in two RNAi hairpin cassettes (C1 and C2) to retain a functional hairpin repeat of around 600 nucleotides in each cassette. The plant transformation vector (pFGC5941) was selected on the basis of herbicide (Basta®, glufosinate) gene marker that is characterized as non-volatile broad-spectrum herbicide causing no hazardous effects on surrounding environment. After vector cloning, synthesized RNAi cassettes (C1 and C2) were stably transformed in potato cv. Desiree and higher transformation efficiency (up to 76%) was observed. Transgenic plants (FC1 and FC2) were confirmed for transgene and copy number and were subjected to further viral resistance assays for two consecutive autumn crop seasons. Upon viral inoculation, FC1 transgenic lines showed resistance against PVX, PVY and PVS infections whereas transgenic lines (FC2) harboring C2 cassette showed resistance against PLRV and ToLCNDV infections when compared with untransformed control lines plants where disease was expressed. These results confirmed the stably acquired RNAi based resistance in both of transgenic lines. The next phase of research was aimed at development of transgenic lines for controlling CIS problem in potato. A synthetic hairpin cassette (C3) was stably transformed in potato cv. Desiree harboring a hairpin 300 nucleotide region of indigenous vacuolar invertase (VInv) gene. For CIS resistance evaluation, tubers harvested from transgenic lines (FC3) and untransformed control lines were cold stored (2-4oC) for up to 180 days. During three stages of storage duration (30, 120 and 180 days), tubers were analyzed for sugar contents (sucrose, glucose and fructose) through High Pressure Liquid Chromatography (HPLC) and Benedict quantitative analysis. The results showed significant reduction in reducing sugars (glucose and fructose) contents in tubers of transgenic lines after 180 days of cold storage as compared to sugar contents in tubers of untransformed control lines. Furthermore, the elevated amount of reducing sugars in tubers of untransformed control lines was correlated with chips color development. The results showed that the chips derived from cold stored tubers of transgenic lines developed a lighter chips color as compared to chips from tubers of untransformed control lines which developed a dark brown color that is believed to be unacceptable to consumers. Further quantitative analysis of acrylamide contents in fried chips will reveal the health hazardous effects of transgenic tubers. In future, field trails and biosafety analysis of transgenic lines will help in better outcome of current research. The results presented in current thesis work will help in better understanding of viral interactions prevailing in potato crop. The use of RNAi technology has proposed an innovative strategy to control multiple viral attacks that will ultimately lead to reduced crop losses and minimized input costs of chemical control measures in farmer’s fields.