Plant Virology Research Paper

Introduction to Plant Virology

1) Field of plant pathology which deal with the study of viruses & virus pathogens and diseases.

2) Employs all the principles and practices of plant pathology

3) for many years, majority of scientists thought plant diseases are caused by microbes and some unknown entities of infectious origin, later named virus and virus like pathogens.

History of Plant virology

Virus disease of plants was known even before the discovery of bacteria.

i) In 752 BC, in poem by one of the Japanese Empress named Koken described the yellow leaf symptoms of Eupatorium. ii) Later in 1576, Carolus Clusius- tulip color breaking is the oldest known example of virus disease. iii) Transmission o fleaf variegations from the scion to the

http://www.ictvonline.org/codeOfVirusClassification.asp

Principles of nomenclature:

The essential principles of virus nomenclature are:-

(i) to aim for stability; (ii) to avoid or reject the use of names which might cause error or confusion; (iii) to avoid the unnecessary creation of names.

(ii) Nomenclature of viruses is independent of other biological nomenclature. Virus taxon nomenclature is recognized as an exception in the proposed International Code of Bio nomenclature (Bio Code).

(iii) The primary purpose of naming a taxon is to supply a means of referring to the taxon, rather than to indicate the characters or history of the taxon.

(iv) The name of a taxon has no official status until it has been approved by ICTV.

ICTV has framed 20 rules for virus nomenclature. among others it recognizes common names, their international meaning and use of existing names.

ICTV Database (ICTVdb): A centralized repository of virus information. it collects information from databases around the world. It facilitated the job of accurate identification and diagnosis of new and important virus

•The universal virus classification system shall employ the hierarchical levels of Order, Family, Subfamily, Genus, and Species.

•Artificially created viruses and laboratory hybrid viruses will not be given taxonomic consideration. Their classification will be the responsibility of acknowledged international specialist groups.

•When it is uncertain how to classify a species into a genus but its classification in a family is clear, it will be classified as an unassigned species of that family

•Taxa will be established only when representative member viruses are sufficiently well characterized and described in the published literature so as to allow them to be identified unambiguously and the taxon to be distinguished from other similar taxa.

2)Rules about naming Taxa

•Existing names of taxa shall be retained whenever feasible

•The rule of priority in naming taxa shall not be observed.

•No person's name shall be used when devising names for new taxa

•Names for taxa shall be easy to use and easy to remember. Euphonious names are