Occurrence, Etiology and Molecular
Characterization of phytoplasma diseases on Solanum lycopersicum crop in
Egypt
Samah A. Mokbel
Department of Virus and Phytoplasma Research, Plant Pathology Research Institute, Agricultural Research Center., Egypt. Dr.SamahMokbel@gmail.com
ABSTRACT: Surveys were carried over the course of the
2012 and 2013 in different areas of tomato-growing fields in Egypt (Giza,
Ismailia, Bani-Sweif, Fayoum and Qena) in order to determine the occurrence and
distribution of phytoplasma associated with diseased tomato plants (Solanum
lycopersycum L.), and to identify and classify the phytoplasma involved. A
detection survey of infected tomato plants, which showed symptoms of big bud,
witches'-broom and phyllody, in all regions of the screened governorates,
reacted positively when assayed by nested polymerase chain reactions (PCR)
using universal phytoplasma-specific primer pair P1/P7 and R16F2n/R16R2.
Similar assays were used to detect phytoplasma interactions with experimentally
host plant. Dienes’ stain was also used for detection of natural infection of
phytoplasma. The phloem of infected tissues showed scattered area stained
bright blue. Different techniques for transmission of phytoplasma to healthy
tomatoes and periwinkles in an insect-proof greenhouse were tested, including
mechanical inoculation, wedge grafting, parasitic plant dodder (Cuscuta
campestris), insects in the family Cicadellidae (leafhopper, Empoasca
decipiens) and in germinated seeds within the fruit, suggesting mechanical
inoculation and seed-transmissible were not feasible while the positive results
were obtained by the other three techniques for host plants with numerous
symptoms obtained later. Application of transmission electron microscopy (TEM)
technique for detection of experimentally inoculated samples, revealed
phytoplasma in the phloem of most of tested samples. Phytoplasma were observed
as rounded bodies, ranging in size from 200 to 600 nm. The molecular
characterization was performed for three different samples representing the
different symptoms of phytoplasma through cloning and direct sequencing.
Key words: Phytoplasma, PCR, Sequencing, Dienes’stain,
TEM, graft, dodder and insect transmission.
How to cite this article:
Ahmed, A.E., Shalaby, O.Y., Dwidar, E.F., Mokbel, A.S. and El-Attar, A.K. (2014). Occurrence, Etiology and Molecular Characterization of phytoplasma diseases on Solanum lycopersicum crop in Egypt. Egyptian J. of Virology, 11(2): 244-261.
