Changes in Phyto-Chemical Status upon Viral Infections in Plant:A Critical Review

Abstract

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.

Defense Responses and Metabolic Changes Involving Phenylpropanoid Pathway and PR Genes in Squash (Cucurbita pepo L.) following Cucumber mosaic virus Infection

“…In fact, pathogen infection-induced increases in phenol levels may further accelerate phenol biosynthesis pathways. Once tomato plants were infected with CMV, the quantity of phenols in the plant increased, promoting the lignification of cell walls and contributing to plant resistance through an enhancement of the immune response [ 8 ]. According to the findings of several other studies, Tomato yellow leaf curl virus (TYLCV) infection also increased the amount of phenols in plants, as shown by Song et al [ 44 ], El-Dougdoug et al [ 45 ], Khalil et al [ 46 ], and Jaiswal et al [ 9 ].…”

“…Viral infection of plants causes changes in polyphenolic contents, primarily involving the up- and down-regulation of phenolic compound concentrations as well as antioxidative enzymes such as polyphenol oxidase, superoxide dismutase, and catalase. These alterations cause cell damage, reactive oxidative species (ROS) production, and the activation of pathogen-mediated defense mechanisms, such as the accumulation of e.g., salicylic acid [ 8 ]. In the pumpkin, Yellow vein mosaic virus (YVMV) infection raised the levels of phenolic constituents, which boosted the plant’s immune system; these phenolic constituents were increased by 73% in infected plant leaves and by 300% in infected fruits as compared to healthy controls [ 9 , 10 ].…”

Plant viruses induce plant volatiles that are detected by aphid parasitoids

“…Infection by a plant virus causes several phenotypic, physical and physiological changes in plants including alteration of color, size, texture, amino acids and phytohormone levels, distortion of cell structures, decrease of photosynthetic capacity in lower leaves and decrease of nutrient uptake resulting in delay of plant growth and development 1 , 2 Some of the plant chemicals altered by plant viruses are carbohydrates and polyphenols, as well as enzymes involved in reactive oxygen species (ROS) production like peroxidase, catalase, ascorbate peroxidase, and superoxide dismutase 3 . Of particular interest is the manipulation of the plant defense pathways by the viruses during the infection process 4 , 5 .…”

Transcriptional responses and secondary metabolites variation of tomato plant in response to tobacco mosaic virus infestation

“…The rise in total phenolic content additionally revealed responses to numerous diseases, including Peper leaf curl virus disease 38 , Fusarium wilt 39 , tomato yellow leaf curl virus 40 , and pepper yellow mosaic virus disease 41 . Also, following a CMV infection, tomato plants had higher levels of phenols, which promoted the ligni cation of cell walls and enhanced the plant's defenses against disease 42 . In the same way, members of the Passi oraceae family showed a 58.3% rise in secondary metabolites like avonoids and polyphenols after being infected with a virus 43 .…”