r

1
V i r u s
2
Introduction to        Plant Virology
       Symptoms        Virus structure     
 Transmission       Virus transport     
 Biotechnology
3
Virus symptoms Virus infected plants can
display a wide range of different symptoms.The
whole plant can be stunted (dwarf-like) and
infected leaves can show abnormal colorations
like mosaics and yellowing. Very often infected
leaves have a rolling or curly appearance and
also the fruits can display various symptoms
dependent on the virus.The yield of crop plants
can be severely reduced by a virus
infection.However, the age of the plants, the
viral strain and many other factors are affecting
both yield and symptoms of infected plants.
4
Virus structure Virus particles are so small
that they can not be seen in a light microscope.
However, by using an Electron Microscope (EM) it
is possible to visualize virus particles.
Dependent on the virus species the particles
can have a number of different forms as shown to
the right. Some viruses are surrounded by a
lipid membrane (shown in blue).
5
Virus structure All virus particles contain a
virus genome (either DNA or RNA).The genome is
surrounded by a large number of proteins (coat
proteins) forming the outher shell of the virus
particle. When detecting viruses by
immunological methods (fx ELISA) it is the coat
proteins of the virus that are detected. In
contrast, the virus genome may be detected by
PCR.
6
(No Transcript)
7
(No Transcript)
8
(No Transcript)
9
Virus transport In order to spread in the
plant viruses take advantage of the plants own
transport system. This involves plasmodesmata
connecting individual cells and the phloem
vessels which can transport the virus to distant
sites in the plant. However, virus particles
(blue) cannot spread through the plasmodesmata
unless these are modified by the virus.For this
purpose plant viruses express various movement
proteins (red) which increases the size of the
plasmodesmata. Several different mechanisms
seems to be involved in this process.
10
Contoh Penyakit Tanaman Karena Virus
11
Nicotiana tabacum
Tobacco mosaic virus (TMV)
12
Tulip breaking virus (TBV) Tulip
13
Virus tungro by wereng hijau (Nephotettix
virescens)
14
Kerdil rumput by wereng coklat (Nilaparvata
lugens)
15
Cucumber Mosaic Virus by Aphis gossypii