الفهرس 
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Abstract
Banana bunchy top disease is the most serious viral disease of banana
worldwide. Banana bunchy top virus (BBTV)) certainly has a significant impact on
the industrial scale of banana production. Banana bunchy top disease (BBTD) is a
detrimental disease affecting banana cultivation in Egypt. Banana plants showing
distinct virus-like symptoms were collected from four different governorates
(Qalubia, Giza, Ismailia and Behira). All collected samples were tested by DAS
ELISA for (BBTV) virus. The results showed that the ratios of infected samples were
3/25, 4/25, 6/25 and 10/25 in the Qalubia, Giza, Ismailia and Behira governorates,
respectively. The diagnostic host of (BBTV) was narrow (banana, ginger, and bird of
paradise). Symptoms on banana plants showed yellowing at the margins and dark
green streaks on leaves, while ginger and bird of paradise showed yellowing at leaf
margins and yellow leaf streaks, respectively. The virus was successfully transmitted
to banana plants and ginger using insect inoculation with Pentalonia nigronervosa.
while the bird of paradise was mechanically transmitted. (BBTV) showed [thermal
inactivation point (70 °C), dilution end point (10-3) and longevity in vitro (24 hrs)
Several anatomical changes were observed reflecting the external symptoms on
infected plants. Examination of ultrathin sections by Transmission electron
microscopy revealed changes in the chloroplast, cytoplasm and in nucleus. By
microtome technique of cross sections of BBTV, Xylem and Phloem cells appear
necrotized and blocked with dark stained material. Polymerase chain reaction (PCR)
detected a 476 bp amplicon from infected banana tissues. The multiple sequence
alignment showed that the (BBTV)-EGY-Behira isolate had high similarity (99.7%)
with the (BBTV) isolate from India. Phylogenetic tree for the EGY-Behira isolate
based on partial nucleotide sequence alignment of the DNA-A genome. Biochemical
contents in infected banana plants showed that phenols in infected samples were
significantly increased (2.797 mg/g) compared with healthy samples (2.617 mg/g).
Total sugar and total indoles were significantly decreased in infected plants (1.966
and 1.129 mg/g) compared with healthy samples (2.269 and 1.206 mg/g),
respectively. BBTV was successfully eliminated from infected seedlings using
thermotherapy at 38°C for two months combined with meristem tip culture at 0.1 mm.
Virazol and salicylic acid (40 mg/L) significantly inhibited virus multiplication in the
infected seedlings. Virazole and salicylic acid provided the greatest polyphenol
oxidase activity (1.64 and 1.78) as well as high peroxidase enzymatic activity (2.021
I
and 1.96), respectively. It was observed that infected plants had the highest reduction
in chlorophyll b (51.47%), followed by chlorophyll a+b (51.27), chlorophyll a (51.17)
and carotenoids (-2.65).