MATERIALS AND METHODS
Plants and virus and insect cultures. Twenty-day-old seedlings
of wild and domesticated tomato, grown in a nursery, were
planted in 0.5-liter pots and kept in an insect-proof nethouse. B.
tabaci of the B biotype (3) were maintained on eggplants (Solanum
melongena cv. Classic) and on cotton (Gossypium hirsutum
cv. Akkala) in insect-proof cages held at 26°C in an insect-proof
growth chamber. Virus isolates were maintained in tomato plants
(L. esculentum cv. Daniela) and propagated by whitefly-mediated
transmission.
Whitefly-mediated inoculation. Insects that acquired TYLCV
during a 48-h acquisition feeding on infected tomato plants were
used for inoculation. An inoculation routine was used to avoid
escape (20). Twenty-day-old seedlings were inoculated in the greenhouse
by caging viruliferous whiteflies for 5 days, 10 to 20 insects
per plant. Fourteen days thereafter, the plants were tested for the
presence of viral DNA by squash blot hybridization (described below).
Plants without detectable viral DNA were individually caged
with 20 to 40 viruliferous insects for an additional 48-h inoculation
period. All plants were then planted in an infested field. The
presence of viral DNA was assayed up to 130 days later, using
squashes of two to four apices for each plant. Symptoms were
monitored for this entire period.
Detection of TYLCV DNA. Approximately 1 cm2
of tissue from
the shoot apex was squashed on a nylon membrane (Hybond N;
Amersham Corp., Arlington Heights, IL) and hybridized (14) with
the radiolabeled plasmid pTYH20.7 bearing tandemly repeated
copies of the cloned genome of a TYLCV isolate from Israel (15).
Viral DNA was also detected by Southern blot analysis (1) and by polymerase chain reaction (PCR) (16)
MATERIALS AND METHODSPlants and virus and insect cultures. Twenty-day-old seedlingsof wild and domesticated tomato, grown in a nursery, wereplanted in 0.5-liter pots and kept in an insect-proof nethouse. B.tabaci of the B biotype (3) were maintained on eggplants (Solanummelongena cv. Classic) and on cotton (Gossypium hirsutumcv. Akkala) in insect-proof cages held at 26°C in an insect-proofgrowth chamber. Virus isolates were maintained in tomato plants(L. esculentum cv. Daniela) and propagated by whitefly-mediatedtransmission.Whitefly-mediated inoculation. Insects that acquired TYLCVduring a 48-h acquisition feeding on infected tomato plants wereused for inoculation. An inoculation routine was used to avoidescape (20). Twenty-day-old seedlings were inoculated in the greenhouseby caging viruliferous whiteflies for 5 days, 10 to 20 insectsper plant. Fourteen days thereafter, the plants were tested for thepresence of viral DNA by squash blot hybridization (described below).Plants without detectable viral DNA were individually cagedwith 20 to 40 viruliferous insects for an additional 48-h inoculationperiod. All plants were then planted in an infested field. Thepresence of viral DNA was assayed up to 130 days later, usingsquashes of two to four apices for each plant. Symptoms weremonitored for this entire period.Detection of TYLCV DNA. Approximately 1 cm2 of tissue fromthe shoot apex was squashed on a nylon membrane (Hybond N;Amersham Corp., Arlington Heights, IL) and hybridized (14) withthe radiolabeled plasmid pTYH20.7 bearing tandemly repeatedcopies of the cloned genome of a TYLCV isolate from Israel (15).Viral DNA was also detected by Southern blot analysis (1) and by polymerase chain reaction (PCR) (16)
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