Papers by abdelrahem mohamed
African Crop Science Journal, 2016
In vitro selection is one of the most effective and efficient techniques for plant improvement. T... more In vitro selection is one of the most effective and efficient techniques for plant improvement. This is due to its ability to isolate plants with the desired character(s), either by applying a selection agent on the culture media to drive the selection of somaclones with the required character(s), or by establishing particular conditions that change in the genomes of somaclones toward the required character. The objective of this study was to identify a suitable protocol for in vitro selection of Allium white rot disease (Sclerotium cepivorum) tolerance in commercial Egyptian onion varieties, namely Giza 20, Giza 6 and Beheri Red. Oxalic acid (OA), the phytotoxin produced by Sclerotium cepivorum, was used as the selective agent. Seeds of the three Egyptian varieties were germinated on four concentrations (0.0, 0.02, 0.2, 2 and 20 mM) of Oxalic acid. Among the tested cultivars, Beheri Red had the highest germination frequency (52%) at all concentrations tested, followed by Giza 20 (42.6%), and Giza 6 at (32%). Cotyledon explants from the varieties were cultured on toxic MS BDK medium, supplemented with 0, 3, 6 and 12 mM OA. The survival of calli on MS BDK free toxic medium was 70.7% for all tested cultivars; however, MS BDK-stressed medium, with 3 mM OA reduced the viable calli to 42.1%. The highest OA concentration (12 mM) completely inhibited calli induction from cotyledons explants. A medium supplement with 3 mM OA retarded 80% of calli growth. Among 156 tested calli of Beheri Red, only 23 calli (14.7%) survived on toxic medium for 45 days. Similarly, there was 15.6% survival for Giza 20 calli, while 40.1% of the Giza 6 calli survived. Plantlets were regenerated from surviving calli and transplanted onto ex vitro, and formed bulb after acclimatisation.
A polymerase chain reaction (PCR) based approach, namely random amplified polymorphic DNA (RAPD) ... more A polymerase chain reaction (PCR) based approach, namely random amplified polymorphic DNA (RAPD) analysis was applied to six genotypes (three cultivars and three somaclones) of onion (Allium cepa L.) in order to assess the degree of polymorphism among them based on their molecular fingerprints as well as constructing dendrogram describing the relationships among them. Six arbitrary 10-base primers were successfully used to amplify DNA extracted from the plant of the six genotypes. All primers showed polymorphic bands except one primer. A total of 55 amplicons (amplified fragment) were generated by tested primers in which 7 of them were polymorphic (12.73 %). The mean number of amplicons per primer varied from 8 to 11. The amplicons was sized 547 bp to1374 bp. The polymorphisms in PCR amplification products were subjected to the unweighed pair group method for arithmetic averages (UPGMA) and plotted in a phenogram. The dendrogram constructed from the similarity data showed that two m...
In vitro selection is one of the most effective and efficient techniques for plant improvement. T... more In vitro selection is one of the most effective and efficient techniques for plant improvement. This is due to its ability to isolate plants with the desired character(s), either by applying a selection agent on the culture media to drive the selection of somaclones with the required character(s), or by establishing particular conditions that change in the genomes of somaclones toward the required character. The objective of this study was to identify a suitable protocol for in vitro selection of Allium white rot disease (Sclerotium cepivorum) tolerance in commercial Egyptian onion varieties, namely Giza 20, Giza 6 and Beheri Red. Oxalic acid (OA), the phytotoxin produced by Sclerotium cepivorum, was used as the selective agent. Seeds of the three Egyptian varieties were germinated on four concentrations (0.0, 0.02, 0.2, 2 and 20 mM) of Oxalic acid. Among the tested cultivars, Beheri Red had the highest germination frequency (52%) at all concentrations tested, followed by Giza 20 (42.6%), and Giza 6 at (32%). Cotyledon explants from the varieties were cultured on toxic MSBDK medium, supplemented with 0, 3, 6 and 12 mM OA. The survival of calli on MSBDK free toxic medium was 70.7% for all tested cultivars; however, MSBDK stressed medium, with 3 mM OA reduced the viable calli to 42.1%. The highest OA concentration (12 mM) completely inhibited calli induction from cotyledons explants. A medium supplement with 3 mM OA retarded 80% of calli growth. Among 156 tested calli of Beheri Red, only 23 calli (14.7%) survived on toxic medium for 45 days. Similarly, there was 15.6% survival for Giza 20 calli, while 40.1% of the Giza 6 calli survived. Plantlets were regenerated from surviving calli and transplanted onto ex vitro, and formed bulb after acclimatisation.
Key Words: Allium cepa, oxalic acid, Sclerotium cepivorum
A polymerase chain reaction (PCR) based approach, namely random amplified polymorphic DNA (RAPD) ... more A polymerase chain reaction (PCR) based approach, namely random amplified polymorphic DNA (RAPD) analysis was applied to six genotypes (three cultivars and three somaclones) of onion (Allium cepa L.) in order to assess the degree of polymorphism among them based on their molecular fingerprints as well as constructing dendrogram describing the relationships among them. Six arbitrary 10-base primers were successfully used to amplify DNA extracted from the plant of the six genotypes. All primers showed polymorphic bands except one primer. A total of 55 amplicons (amplified fragment) were generated by tested primers in which 7 of them were polymorphic (12.73 %). The mean number of amplicons per primer varied from 8 to 11. The amplicons was sized 547 bp to1374 bp. The polymorphisms in PCR amplification products were subjected to the unweighed pair group method for arithmetic averages (UPGMA) and plotted in a phenogram. The dendrogram constructed from the similarity data showed that two main clusters were resulted. One of them included the genotypes Giza 20 and Giza 20 somaclone while, rest of genotypes was included in the second one. The second cluster was divided into two sub clusters one included genotypes Bihir red and Giza 6 while, the other sub cluster involved the somaclones of both cultivars Bihir red and Giza 6. It could be concluded that RAPD can be successfully used to detect somaclonal variations among in vitro regenerated onion plants.
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Papers by abdelrahem mohamed
Key Words: Allium cepa, oxalic acid, Sclerotium cepivorum
Key Words: Allium cepa, oxalic acid, Sclerotium cepivorum