Browsing by Author "A Youssef, Sahar"

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    Molecular Characterization and CytopathologicalStudiesofPotato Virus YIsolatedfrom Potato Sprout in Egypt
    (Int. J. Adv. Res. Biol. Sci, 2016) A Youssef, Sahar; Arafa, Eslam; Shalaby, AA; Safwat, Gehan
    Potato Virus Y(PVY) is a plant pathogenic virus fromPotyviridaeand it belongs toPotyvirusgenus. PVY is an aphid-bornevirus that causes yield losses and tuber quality defects in commercial potato crops in Egypt. Infected seed potato tubers aretheprincipal source of PVY spread to other potato plants.PVY was readily detected by RT-PCR of tuber sprouts. Molecularcharacterization of PVY isolated from infected potato sprout was investigated by reverse transcription-polymerase chain reaction(RT-PCR) and nucleotide sequencing analysis in addition to cytopathological study to detect the presence of virus infection ininfected sprout tissue. Analysis of RT-PCR amplified cDNA product from infected tissue using primers designed to amplify thecoat protein gene of the PVY genome verified that thePotyvirusinfecting potato sprout is an isolate of PVY. These results wereconfirmed by nucleotide sequence analysis. Nucleotide sequencing of the PVY CP gene showed about 99%identitiy to that ofother PVYNTNisolate. Transmission electron microscopy (TEM) negative staining methods were used in order to detect thepresence of viral cytoplasmic inclusion bodies. Typical pinwheels, scrolls, laminated aggregates and disruption of normal cellswas observed in PVY infected potato sprout. RT-PCR technique has primarily been developed for large-scale screening of manysamples for determining viral incidence in commercial fields or seed lots, and also amenable to use in smaller-scale researchapplications
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    Universal and Specific 16S-23Sr RNA PCR Primers forIdentification of Phytoplasma associated with sesame in Egypt
    (International Journal of Advanced Research in Biological Sciences, 2017) A Youssef, Sahar; Sayed, Yasmin; S Hassan, Osama; Safwat, Gehan; Shalaby, AA
    Sesame (Sesamum indicumL.), familyPedaliaceaeis one of the most ancient cultivated oilseed cropsamong the edible annualgroup in Egypt and all over the world. Phytoplasmas are pathogens of many plant species throughout the world including sesamecausing a large variety of symptoms ranged from mild yellowing to death of infected plants.Symptomaticsamples includinggreen leaf-like floral organs,virescence, phyllody and proliferationwere collected from infected sesame field in GizaGovernorate.This research was undertaken to develop a diagnostic tool to identify phytoplasmas recently discovered infectingsesame in Egypt, and to classify them according to their phylogenetic group. Direct and nested PCR primers of 16S-23SrRNAgene, paired with phytoplasma universal primer followed by strain-specific PCR primers were used in this study. Spacer Region(SR) primers were employed for identification of Phytoplasma group associated with sesame symptoms. Results showed thepresences of mixed infections of phytoplasma in the tested sesame samples which collected from the field with different typeofPhytoplasma like symptoms. Results also indicated thatpolymerase chain reaction with primers from sequencing of 16S-32SrRNA and from SR opened new paths for research on phytoplasma identification and classification. Nested PCR has been appliedto overcome problems related to sensitivity of phytoplasma detection, although this approach is more time consuming and subjectto template. Unfortunately, nested-PCR also meets some difficulties: unspecific bands, false positives or negatives caused byDNA and contaminationof single or nested PCR. Therefore, confirmation of PCR results by using different primer paircombinations (generic and group-specific) seems to be the way for correct phytoplasma identification in the examined sesamesamples