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Articles by A. Helmi
Total Records ( 2 ) for A. Helmi
  A. Helmi
  Whitefly, Bemisia tabaci (Genn.) is an important sucking plant sap pest of field, horticultural and ornamental plants causing feeding injuries besides spreading plant diseases by acting as a vector of Gemini-viruses. The polyphagous nature of the pest makes it as a highly complex species. The influence of six host plants belonging to three different plant families utilized by the species on the population differences at molecular level was attempted using Random Amplified Polymorphic DNA (RAPD) markers. Fifteen RAPD primers were screened seven of them were produced 218 DNA fragments, 209 of them were polymorphic while the other nine bands could be considered as common for B. tabaci. Total number of bands obtained from each primer ranged from 23-44 with an average of 36.33 bands per primer. RAPD-PCR analysis led to identification of 42 polymorphic markers holding specificity for these hosts' populations. Phylogenetic relationships among the studied populations using this technique clearly separated these six populations into two main clusters with similarity matrix percentage of 88 and 64%. These results indicated that B. tabaci may have different genotypes on adaptations to certain host plant species in Egypt.
  A. Helmi and A.F. Khafaga
  Cereal aphids are one of the most important insect pests limiting cereal production worldwide. Classical morphological criteria for aphid species identification may be affected by environmental factors such as climatic conditions and physiological status of the host plant. So, two modern molecular techniques; Random Amplified Polymorphic DNA (RAPD) and Inter Simple Sequence Repeats (ISSRs) were used to find diagnostic markers for fingerprinting eleven cereal aphids those collected from different cereal plants and from different localities in Egypt. Eight RAPD and five ISSRs primers were successfully produced 97 and 69 markers that could be used to differentiate the eleven different cereal aphid species. Also these molecular techniques with 23 diagnostic morphological characters were used to find the Phylogenetic relationship among the different collected species; that divided into two clusters with similarity matrix percentages of 73 and 82%. From these results it could concluded that these techniques could be successfully used successively to fingerprint and identify these aphid species and differentiate among them.
 
 
 
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