classification of plant viruses (plant pathology+Botany)

1. CLASSIFICATION OF
PLANT VIRUSES
MOHD SALIM
18-BTM-028
GK7985
DEPTT.OF BOTANY
AMU.ALIGARH

2. WHAT IS PURPOSE OF CLASSIFICATION
Grouping of biological entities according to their resemblances
and differences
To make structural arrangement for easy comprehension
To enable prediction of properties of new viruses
Possible evolutionary relationships
To be able to communicate with each other

3. VIRUSES
Viruses are ‘Sub-microscopic’infective entities that multiply only
intracellularly and are potentially pathogenic
 Nucleic acid either-RNA or DNA
Genome enclosed within protein coat-Capsid
Different shapes (Helical,polyhedral,isometric,rod like or
filamentous ) -size vary from 20-300nm
Nucleic acid 5-40% and protein 60-95%
These may enveloped or non enveloped

4. CRITERIA USED FOR CLASSIFYING PLANT VIRUSES
Structure of the virus particle (monopartite,bipartite,tripartite)
Physiochemical properties of the virus particle
Properties of viral nucleo-protien
On the basis of symmertry ( eg.helical viruses)
Number and arrangement of protein sub-units (eg.isometric
viruses)
Size of viruses

6. CLASSIFICATION OF VIRUSES
• Virus classification starts at the levels of order and continues as
follows ,with the taxon suffixes given in italics:
Order (-virales)
Family (-viridae)
Sub-family (-virinae)
Genus (-virus)
Species
Species –English common name
ICTV-[Family] is the highest taxonomic category of viruses

7. PLANT VIRUSES
ssRNA viruses- Non enveloped
1.Rod shaped viruses
e.g Tobamovirus (300*18nm)
Tobravirus (40-20*22nm)
Hordeivirus (100-150*20nm)
2. Filamentous viruses
e.g Potexvirus (480-580*13nm)
Carlavirus (610-700*13nm)
Trichovirus (730*12nm)

8. 3.ISOMETRIC VIRUSES
Monopartite viruses
e.g Necrovirus 30nm
Tymovirus 30nm
Tombusvirus 30nm
Bipartite viruses
e.g Comovirus (25-30nm)
Nepovirus
 Tripartite viruses
e.g Cucumovirus 29nm
Ilarvirus (26-35nm)
 Multipartite viruses
e.g Alfamovirus (28-58*18nm)
Tenuivirus

9.  SSRNA VIRUSES (ENVELOPED VIRUSES)
e.g Cytorhabdovirus ( 70*170nm)
Tospovirus 80nm
 dsRNA viruses (NON-ENVELOPED)
e.g Phytoreovirus 70nm
Oryzavirus 70nm
(+) ssDNA viruses
e.g Mastrevirus 28-30nm
dsDNA viruses
e.g Caulimovirus 50nm

16. REFRENCES
GEORGE N.AGRIOSE-Plant
pathology
SINGH.PANDE.JAIN-5th edition
ARUN KATYAYAN-
Fundamentals of agriculture
https://www.researchgate.net-
Recent classification of plant
viruses
Ecoursesonline.iasri.res.in

17. Type equation here.