MOHD SALIM, Transmission of plant viruses

1. TRANSMISSION OF PLANT VIRUSES
MOHD SALIM
18BTM028
GK7985
Deppt.of botany
AMU,ALIGARH

2. DIFFERENT MODE OF PLANT VIRUS TRANSMISSION
Plant viruses are transmitted from plant to plant in a number of ways:
VEGETATIVE PROPAGATION
MECHANICAL TRANSMISSION
SEED TRANSMISSION
POLLEN TRANSMISSION
INSECT TRANSMISSION
MITE TRANSMISSION
NEMATODE TRANSMISSION
FUNGUS TRANSMISSION
DODDER TRANSMISSION

3. VEGETATIVE TRANSMISSION
 When plants viruses are propagated by budding or
grafting,by cuttings or by tubers,corms,bulbs,or
rhizomes,virus present in the mother is transmitted
to the progeny.
 Almost all fruit,many ornamental plants,field crops
and most florists crop propagated.
 Natural root grafts

4.  MECHANICAL TRANSMISSION
 Direct transfer of sap through contact of one
plant with another.
 Young leaves are crushed.
 Buffer solution are added to stabilized the
virus
 The sap is strained to remove tissue fragments
 Leaves of young plants dusted with an
abrasive –corborundum.
 Sap is applied to the surface of young plants.
 Virus enters the leaf through wound or broken
leaf hairs
 Symptoms usually appear within 3-7 days.

5.  SEED TRANSMISSION
More than 100 viruses are transmitted
by seed .
Virus comes mainly from ovule of
infected plants.
Seed is derived from the pollen that
fertilized the flower.

6.  POLLEN TRANSMISSION
Virus transmitted by pollen may
result in reduced fruit set,may infect
the seed and seedling that will grow
from it.
Spread through the fertilized flower
and down into the mother
plant,which thus becomes infected
with the virus
E.g Prunus necrotic ring spot virus

7.  INSECT TRANSMISSION
 Most important means of transmission of
viruses in the field by the insect vectors.
 Order –Homoptera
Aphids (Aphididae)
Leafhoppers (Cicadellidae)
Planthoppers (Delphacidae)
Whiteflies (Aleurodidae)
Mealybugs (Coccoidae)
Treehoppers (Membracidae)

8.  MITE TRANSMISSION
Primarily mites of the family Eriophyidae
have been shown to transmit at least six
viruses including wheat streak mosaic and
several other rymoviruses affecting
cereals.These mites have piercing and sucking
mouth parts. Peach mosaic virus is transmitted
by mites of the family Tetranychidae

9. NEMATODE TRANSMISSION
 Nematode plant viruses are transmitted by
three genera of soil inhabiting.
 Ectoparasitic nematode e.g, Longidorus
,Paralongidorus, and Xiphinema transmit
 Several polyhedral shaped- nepovirus
 such as grapes fanleaf, tobacco ring spot,
and other viruses.
 Trichodorus and paratrichodorus transmit al
least two rod shaped tobraviruses ,tobacco
rattle, and pea early browning.

10.  FUNGUS TRANSMISSION
Root- infecting fungal like organism, the
plasmodiophoromycetes polymyx and
spongospora and the chytridiomycete
olpidium
transmit at least 30 plant viruses.Some of
these viruses apparently are borne internally
in , whereas others are carried externally on
the resting spores and the zoospores of the
fungi.

11.  DODDER TRANSMISSION
Several plant viruses can be transmitted from
one plant to another through the bridge formed
between two plants by the twining stems of the
parasitic plants dodder (Cuscuta sps.) A large
number of virus have been transmitted
experimentally. The virus is usually transmitted
passively through the phloem of the dodder
plant from the infected plant to the healthy one.