Most damaging plant diseases have been caused by viruses in the entire world. In tropical and subtropical areas, the damage caused by plant virus leads to great economic and agricultural losses. Single stranded DNA viruses (geminiviruses) are the most perilous pathogens which are responsible for major diseases in agronomic and horticultural crops. Significantly begomoviruses and mastreviruses are the biggest genus of plant infecting viruses, transmitted though Bemisia tabaci and members of Cicadellidae respectively. Plants possesses some naturally existing chemicals term as phyto-chemicals which perform important functions in the plant. Some antioxidant enzymes are used by plants for selfdefense upon foreign invasion of infection. This review explains the present perceptive of influence of viral infections on phyto-chemicals, oxidative enzymes and biochemical changes occurring in the plant. Viral infection mediated phytochemical changes in plants mainly includes: up and down regulation of photosynthetic pigment, increase in the concentration of phenolic compounds, elevation of starch content in the leaf and up & down regulation of anti-oxidative enzymes including (GPX) guaiacol peroxidase, (PPO) polyphenol oxidase, (APX) ascorbate peroxidase, (SOD) superoxide dismutase and (CTA) catalase. These changes lead to initiation of hypersensitive response, by thicken of the leaf lamina, lignification under the leaf surface, blocking to stomatal openings, systematic cell death, generation of reactive oxidative species (ROS), activation of pathogen mediated resistance pathways i.e., production of salicylic acid and jasmonic acid. Collectively all the physiological changes in the plant due to viral infection supports the activation of defense mechanism of the plant to combat against viral infection by limiting virus in specific area, followed with the production of barriers for pathogen, accumulation of starch in the leaf and excess production of (ROS). These strategies used by the plant to prevent the spread of virus in whole plant and to minimize the risk of severe yield loss.

Mycoviruses are viruses that infect fungi. They have been reported in all major taxa of fungi. Generally extracellular phase is not present in mycoviruses and are transmitted during cell division intracellularly in sporogenesis, and/or hyphal anastomosis. The genome of mycoviruses has dsRNA, but a number of positive- or negative-strand ssRNA and ssDNA viruses have been isolated and characterized. There is an increasing interest for use of mycoviruses as novel biocontrol agent as they reduce the virulence of their phytopathogeinc fungal hosts. Mycoviruses can also infect endophytic fungi and encode killer toxins. Better understanding of mycoviruses assembly, function, and evolution have been done through their structural analyses. Recent report on virus taxonomy suggested that mycoviruses genome mostly consists of double-stranded RNA (dsRNA), and about 30% of mycoviruses genome is composed of a positive, single-stranded RNA (+ssRNA). Recently a mycovirus that is related to Gemini viruses has been reported. Scientists have reported mycoviruses in Chytridiomycota, Zygomycota, Ascomycota, Deuteromycota, and Basidiomycota. Many mycoviruses and their fungal hosts still remain unknown recently developed metagenomics approaches will be useful for detecting and identifying new mycoviruses

Wheat is one of the most important staple food crop .Wheat streak mosaic virus (WSMV) was first time reported in Nebraska in 1922 as "yellow mosaic". Since then, although sporadic in its appearance and severity, wheat streak mosaic has caused losses throughout North America, Europe, North Africa and Russia. The disease was probably present in other counties, but was not detected. WSM symptoms are characterized by a yellow leaf streaking or stippled pattern and stunting, head sterility, low test weights, and poor tillering and it is a seed born or mite born disease.WSMV is transmitted by eriophyid mite in both semi persistent and circulative manners. Mostly WSMV infects the crops belonging to family graminae or Poaceae (wheat, barley) and other alternate host of the WSMV are the grassy weeds or green bridge where wheat curl mite (WCM) over winters and lay eggs in the absents of the host. Wheat production in the Great Plains is also threatened by the newly discovered wheat viruses including Wheat mosaic virus and Triticum mosaic virus (TriMV). Both viruses closely match the life cycle of WSMV and are transmitted by WCM. Genome of WSMV contains positive sense ssRNA virions and one polyprotein. The tritimovirus which is approximately of 10kb in size

Pesticides driven from Plants, animals, and microbes such as (bacteria fungi, viruses, algae, nematodes and protozoa are replacing traditional chemical pesticides throughout the world. Bio pesticides reduce environmental risks and are target specific. Bio pesticide promotes sustainable agriculture development by reducing the environmental pollution. Various products have been registered and released, that play important role in the agro-market. Regulation of many insect populations in nature happen by Baculoviruses (entomopathogenic viruses). The pesticide based on baculovirus particles has been formed to control pest and their use is beneficial to reduce the risk of synthetic chemical insecticides. The present status and increase use of baculovirus based bio pesticides as replacement of chemical pesticides, its role in integrated pest management, have been discussed in this review.