Transformation of Sequences Related to Viral Capsid Protein

Biotechnology in Agriculture
The New Green Revolution
Nucleic Acids
Protein Synthesis
Southern and Northern Blot Techniques
Nucleic Acid Hybridization
Recombinant DNA Technology and Gene Cloning
Some Restriction Enzyme Sequences the Arrow Indicates Actual Clevage Site
Gene Exchange in Bacteria
The Agrobacterium Mediated Transfer of Genes
Procedures for Agrobacterium Mediated Transformations
Direct DNA Transfer Technologies
Antisense RNA Strategy
Frost Control Biotechnology
Virus Resistance in Transgenic Plants
Transformation of Sequences Related to Viral Capsid Protein
Resistance Conferred by Antisense RNA
Antibody Mediated Resistance

Transformation of Sequences Related to Viral Capsid Protein

	Transformation of Sequences Related to Viral Capsid Protein Coat mediated resistance is the expression of a gene that causes the transformed cell and regenerated transgenic plants to produce the coat protein (CP) of a virus thereby conferring resistance to infection in the transgenic plant. Plants that accumulate large amounts of coat protein escape/mini Elementary features of typical virus particles: A-Enveloped icosahedral virus; BNaked icosahedral virus; C-Enveloped helical virus and D-Naked helical virus maize virus infection.
Elementary features of typical virus particles. >
The CP mediated resistance was first reported in tobacco mosaic virus (TMV) in 1986. Subsequently several instances of resistances for several virus diseases of plants have been reported which include tomato mosaic virus, alfalfa mosaic virus, cucumber mosaic virus, tobacco streak virus, potato virus x and y, tobacco etch virus, tobacco rattle virus, potato leafroll virus, potato virus S.
A point which needs to be stressed is that CP mediated resistance does not provide immunity to transgenic plants; for instance TMV resistant plants that expressed CP gene were susceptible to inoculum levels of 10mg/ml while plants that were not transgenic got infected even at inoculum levels of 0.001-0.01 mg/ml. Despite the fact that the mechanism involved in CP mediated resistance has not been clearly understood, some kind of inferences can be made from studies on TMV diseases in tomato and tobacco. Firstly, the transgenic plants are protected due to reduction in the number of infection sites that means fewer number of plants may get infected than controls. Secondly, the transgenic plants are less likely to develop systemic infection and thirdly, such plants may produce less virus particles than the ones not having the resistant gene.
	Transformation of Sequences Related to Viral Movement Protein A gene product of TMV was the first to be directly identified and investigated in viral movement. Plasmodesmata are the portals between adjacent host plant cells responsible for viral movement. A gene product (viral protein) has been found to accumulate at or near plasmodesmata of TMV infected transgenic plants especially in the cell wall fraction, which directly or indirectly changes the plasmodesmatal permeability to allow the passage of TMV particles measuring 18 x 300 nm (30-KDa) while in the normal tobacco plants only low molecular weight compounds less than 1.5-2.0 nm could pass through.

However, microinjection of recombinant viral protein into plant cells resulted in the enhancement of plasmodesmatal expansion upto 9nm limit, that was insufficient for viral movement to take place between host cells and hence an alternate explanation had to be found.

It is known that the viral protein also binds to RNA and hence it has been conceived that one part of the viral protein binds to TMV virus RNA and shapes into a complex measuring about 2nm and the other part of the protein binds to plasmodesmata to increase their permeability character and thus enable the virus to pass through plasmodesmata.

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