PPATH 221: Plant Virology. K. M. Golam Dastogeer Lecturer Department of PLANT PATHOLOGY BANGLADESH AGRICULTURAL university. WELCOME. Definition of a Virus.
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K. M. Golam Dastogeer
Department of PLANT PATHOLOGY
BANGLADESH AGRICULTURAL university
(I) Living characters of viruses:
Following characters of viruses assign them as non-living:
(a) They can be crystallized.
(b) Outside the cell, they behave like inert chemicals.
(c) They do not show growth, development, nutrition, reproduction, etc.
(d) No physiological activity
(e) Do not reepire or excrete
(f) They can be precipitated.
Because of the above reasons, viruses form unique bridge between living and non-living things.
Based on biological properties
2. Transmission tests
and vector transmission
3. Physical properties
thermal inactivation point, dilution end point, and
longevity in vitro)
eins become light and more distinct
Leaf rolling and curling: Rolling is folding of leaves along their mid axes resulting in a more or less tube-like structure. When the folding is more irregular or does not result in a tube-like structure it is usually referred to as leaf curling.
RugoseRugose means : "rough leaves". This term covers both crinkling (leaves looking edged or wrinkled) and leaf puckering (blister-like irregularities formed on the leaf)
Pea enation mosaic virus (PEMV)
Crown gall/ tumor
Rosette: cluster leaves