Characterizations of the Egyptian isolate of Onion yellow dwarf virus Infecting onion and development of Virus-Free plantlets
Characterizations of the Egyptian isolate of Onion yellow dwarf virus Infecting onion and development of Virus-Free plantlets
Ahmed K. El-Attar; Samah A. Mokbel; Ali H. Hamed
ABSTRACT
Onion yellow dwarf disease is an economically important disease of onion (Allium
cepa L.) caused by Onion yellow dwarf virus (OYDV). In this research we aimed to
identify and molecularly characterize the isolate of the OYDV infecting onion plants in
Egypt and to obtain OYDV-free plants from infected onions through tissue culture
techniques. To achieve our aim, the virus has been isolated from naturally infected onion
plants grown in five Egyptian Governorates, Gharbia, Qalyobia, Giza, Fayoum and Beni-
Suef then mechanically transmitted onto healthy onion plants in an insect proof
greenhouse. The virus identification was done by indirect ELISA using specific
antiserum and confirmed by Reverse Transcriptase-Polymerase Chain Reaction (RTPCR)
using virus-specific primers. The molecular characterization for the Egyptian
isolate has been performed through cloning and sequencing for the OYDV CP gene
which amplified by RT-PCR then cloned and sequenced in the TOPO cloning vector. The
CP gene sequence has been submitted to the GenBank and compared to other available
isolates of OYDV. Sequence alignment and phylogenetic analysis showed that the
Egyptian isolate of the OYDV is related to other isolates from Japan, Netherlands, Israel,
Brazil, China, India, and Poland with a similarity ranged from 70 to 93% among those
isolates available on GenBank. The virus was eliminated from infected onion plants using
cytokinin (kinetin) in a tissue culture line to obtain the OYDV-free plantlets. The effects
of different concentration levels of kinetin as well as its efficacy on the OYDV
elimination and regeneration of infected onion bulbs were determined.
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July 2014
Vol. 11, Iss. 2, Pages 1-310
