Begomovirus infections are one of the main biotic stress for plants. These viruses are transmitted by whitefly. Begomoviruses have emerged as important viral pathogens of all types plants in the world. Viral infections are extremely difficult to control and their physiological consequences can be highly variable so, leading to a continued lack of understanding of their effects. This study indicates the effect of agro-infiltration of infectious clones of begomoviruses on the physiology of tomato and tobacco plants which interact with the host defense mechanism. It was found that the leaf RWC,TSS, fresh and dry biomass, photosynthetic pigments were more in healthy plants as compared to infected plants. Plant infected with (ToLCNDV) and (CLCuV+CLCuB) showed reduced TSS and leaf RWC as compared to healthy plant. Among infectious clones Cotton leaf curl burewalla virus associated with betasatelite (CLCuV+CLCuB), (ToLCNDV) caused more reduction while (MYVCMV) caused more reduction while (MYVCMV) caused less reduction as compared to above mentioned clones. Overall this book will provide the information on the symptoms and physiology of tomato and tobacco upon begomovirus infection.