HOST-VIRUS INTERACTION: MOVEMENT OF PLANT VIRUSES THROUGH PLASMODESMATA AND EFFECT ON CHLOROPLAST STRUCTURE: A REVIEW

Virus-host interaction is providing extensive insight mechanisms by which viruses transfer and number of pathways are used for movement within the plant system. Plasmodesmata are a common way for the movement of plant viruses and allow cell-to-cell trafficking of virally encoded movement protein (MP) produced by viruses. Plant viruses move cell to cell through this channel and replicate their genomes by virus replication complexes (VRC) in which viral replicase proteins, viral RNA templates and host proteins factors are involved for replication. Plasmodesmata have some identified genes such as sxd1, ise1and ise2 that are responsible for the relationship with chloroplast. Sxd1 failed to export photosynthate and loss of ise2 gene defect chloroplast and leaves become yellow. Infected chloroplasts with viruses are shown different ultrastructure e.g. swollen or globule chloroplast, amoeboid-shaped chloroplast, the formation of stromule, cytoplasmic invagination. Abnormality in photosynthetic structures such as the disappearance of grana stacks, stroma or dilated thylakoid and completely chloroplast damage and develop chlorosis, necrotic and mosaic symptoms. Sometimes, signalling molecules (SA and JA) are created and show a defense mechanism against viral attack in the chloroplast.