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Hibiscus rosa-sinensisis a valuable ornamental species widely planted in Egypt. The Phytoplasma associated witches’-Broom has been detected on symptomatic hibiscus plants. Samples of hibiscus leaves were collected from El Giza, Alexandria, Qlubia, El-Fayom, and El-Mansoura governorates and analyzed for phytoplasma infection. The collected hibiscus plants showed characteristic symptoms for Phytoplasma associated witches’-Broom disease, which is characterized by excessive axillary branching, abnormally small leaves, and deformed flowers. Dienes’ stain was used for detection of witches’ broom infection midribs of the symptomatic hibiscus plant. The phloem of infected tissues showed scattered area stained bright blue. Molecular detection utilizing nested and direct PCR as well as DNA sequencing was used for the diagnosis of the witches’ Broom infection. Total DNA was isolated from leaf tissues of infected hibiscus plants. Nested polymerase chain reaction (PCR) was performed using the universal - phytoplasma specific primers; P1/P7, R16F2n/R16R2. Witches’ broom specific primers SR1/SR2, at the spacer region (SR), were used for the direct PCR. Amplicons of expected size characteristic for phytoplasma associated witches’ broom were obtained from infected hibiscus samples. DNA sequencing and phylogenetic analysis of the 16S rRNA gene fragment from the hibiscus witches' broom phytoplasma showed 100% homology with the same region of the hibiscus witches' broom strain that isolated in Brazil (Phytoplasma Brasiliense). The DNA sequence was submitted for the gene bank as the first report of the Brasiliense phytoplasma associated witches’ broom affecting hibiscus in Egypt.


Dr. Samah Mokbel 2017-04-16 12:09 1 comment
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Dr. Samah Mokbel