PCR-based detection and partial genome sequencing indicate high genetic diversity in Bangladeshi begomoviruses and their whitefly vector, Bemisia tabaci

Maruthi, M.N., Rekha, A.R., Mirza, S.H., Alam, S.N. and Colvin, John (2007) PCR-based detection and partial genome sequencing indicate high genetic diversity in Bangladeshi begomoviruses and their whitefly vector, Bemisia tabaci. Virus Genes, 34 (3). pp. 373-385. ISSN 0920-8569

Abstract

The population diversity of Bangladeshi
begomoviruses and their vector, Bemisia tabaci was
analysed by PCR-based detection and partial genome
sequencing. B. tabaci adults and plants expressing
symptoms of virus infection were collected from locations
representing diverse agro-ecological regions of
the country. Universal and species-specific primers
were used to detect begomoviruses in seven crops
(chilli, okra, papaya, pumpkin, sponge gourd, tomato
and yardlong bean) and two common weeds (Ageratum
conyzoides and Croton bonplandianum). At least five
distinct species of tomato leaf curl viruses infected
tomato and other host-plants. Phylogenetic analyses of
their nucleotide sequences (~530 bases) from the
intergenic region and capsid protein of DNA-A indicated
the existence of five distinct clusters of begomoviruses.
Begomoviruses infecting tomato, chilli and
dolichos have been reported previously, and those
infecting Ageratum, Croton, okra, papaya, pumpkin
and yardlong bean are described for the first time.
Phylogenetic analyses based on mitochondrial cytochrome
oxidase I gene sequences of 21 B. tabaci from
Bangladesh and other reference sequences grouped
them into at least two independent clusters. Some
sequences from different countries, e.g., Bangladesh,
China, India, Nepal, Pakistan and Thailand were almost
identical while others collected from plants within the
same field diverged by as much as 15%, indicating high
diversity even at the local level. None of the B. tabaci
from Bangladesh grouped with the reference B- and
Q-biotype sequences, thus these two aggressive
biotypes were apparently absent from Bangladesh

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