الفهرس 
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Abstract
The present work was undertaken to gain certain information that may led to overcoming the problems that are caused as a result of infection by such disease in the field to find alternative control strategies of plant pathogens due to the problems of fungicide application as the carcinogenic effects, environmental pollution and development of fungicide-resistant strains. The use of biological agents to induce the plant defence mechanism against pathogens represents an ecologically friendly alternative to fungicides, which must be repeatedly used for the control of plant diseases.
The obtained results of this investigation can be summarized as follows:
1. Twenty three isolates of Botrytis spp. were isolated from naturally diseased onion heads “umbels” showing Botrytis Onion Umbel Blight (BOUB) symptoms. All isolates were pathogenic to umbels of onion plants, B. allii isolate Nos. 1, and 5, were exhibited moderate to high virulence, the percentages ranged between 45-75 %.
2. RFLPs are highly reproducible and allow greater precision for estimating genetic parameters, but are more labor intensive specific DNA primers for amplification and subsequent differentiation of four Botrytis spp. associated with umbel blight disease, using sequence characterized amplified regions (SCARS):BA2f using a polymerase chain reaction (PCR) assay, DNA product from all four species of Botrytis that cause umbel blight disease of onion. Restriction fragment length polymorphism (RFLP) analysis of the PCR amplicon using the restriction enzyme ApoI distinguishes the following diagnostic DNA bands. It was shown as B. aclada, B. allii, B. cinerea, and B. squamosa.
3. The isolates of Botrytis spp. were varied in their cellulases and pectinase activities, isolates of Botrytis aclada Nos. 1 and 2 showed near activity for each other. Over all isolates Botrytis squamosa and B. allii No. 1 shown high activity.
4. A total of 71 DNA bands ranged from 100 bp (OPA03) to 1600 bp (OPA15) were generated by the five primers for the nine isolates of Botrytis species. Out of the 71 bands obtained, 45 (63.38%) were polymorphic studied. The highest number of amplified DNA fragments was detected for the Primer OPA05 (17 bands).
5. Isolate of Botrytis allii No. 5 displayed the highest number of DNA fragments (50 bands), while Botrytis cinerea No. 2 revealed the least number of bands (34 bands).
6. The OPA03 primer showed specific positive band for Botrytis allii isolates Nos. 1, 5, 7 and 3, B. cinerea No. 3 and B. aclada No. 1 with molecular weight of 220 bp and negative bands for Botrytis squamosa 1, B. cinerea No. 2 and B. aclada No. 2 . OPA09 primer produced specific positive bands for Botrytis allii No. 3 with molecular weight (193 bp), and negative band at molecular weight 256 bp. OPA06 primer showed two negative specific bands for Botrytis allii Munn., No. 7, with molecular weight 347 bp and 454 bp and two positive specific bands for molecular weights of 411 and 175 bp respectively. OPA15 primer produced one positive and one negative specific band for Botrytis allii No. 5 with molecular markers (326 and 534 respectively).
7. Reaction of some cultivars to the disease was studied and showed that Giza 6 cultivar showed highest percentage of susceptibility with 86 % followed by other tested cultivars, Giza 20, Giza red, and Shandaweel 1 by 75, 75 and 74.2 % disease severity, respectively.
8. The banding patterns of protein parents of four cultivars were variable. The highest numbers of bands were found in onion Shandaweel 1 cultivar while the other cultivars (Giza 6, Giza 20 and Giza red) were equal in the observed number of bands. The difference in Shandaweel 1 cultivar can be the raison for tolerance of this cultivar for the BOUB.
9. Ascorbate Peroxidase isozyme conferred by ascorbate Peroxidase experiment which was non-activated in the benin cells of non-infected onion plants that confirmed the rule of ccatalase and Aascorbate Peroxidase are two important antioxidant scavenging enzymes involved in the removal of H2O2. Catalase plays the role of a specific peroxidase (POX) protecting the cells from the toxic effects of H2O2. The weak bands of Giza 6 cultivar in β 1,3 glucanase and catalase can be the cause of the susceptibility of Giza 6 cultivar for BOUB.
10. All tested microorganisms were able to inhibit the mycelial growth of B. allii. B. cinerea, B. aclada, and B. squamosa, with variation in their antagonistic capabilities. The highest inhibition for B. allii caused by Trichoderma viride No. 1, T. harzianum No. 1 and T. viride No. 1, and Penicillium chrysogenum No. 1, while, T. pseudokoningii and T. longirum, showed the lowest mycelia growth inhibition.
11. Aqueous plant extract was able to inhibit the mycelial growth of the causal pathogens with variation in their ability, the highest inhibition of B. squamosa (78%) and B. allii (70 %), were obtained by Citrullus colocynthis with concentration of 10%. also the other plants extract of Sinapis arvensis, and Ocimum basilicum showed lowest inhibition even at high concentration.
12. The highest weight of 1000-seed was obtained by P. chrysogenum treatment with 2.88 g followed by C. colocynthis application before infection. While the lowest ones obtained by T. viride application before infection with 1.8 g Treatment with C. colocynthis after infection gave the highest weight (4.08 g) followed by P. chrysogenum (2.64 g).
13. Application of P. chrysogenum, C. colocynthis and S. cerevisiae after infection showed significant differences in total phenol contents for all treatments compared to untreated plants. After eight days all treatments significant increases in total phenol contents than that infected control.
14. The highest Peroxidase activity was observed when plants treated after infection by P. chrysogenum followed by C. colocynthis, at eight days from application. The different applications showed significantly increasing in Peroxidase activity after six days from treatments.
15. The highest value in phenylalanine ammonia-lyase (PAL) activity was detected in treatments after infection by C. colocynthis and P. chrysogenum application followed by P. oxalicum and T. viride.
16. Salicylic acid (SA) amount was significantly increased more rapidly by application of Citrullus colocynthis, T. viride and P. chrysogenum, after the fourth day to the eightth day from the treatment.
17. In treatments after infection the PR Protein II (β 1, 3 Glucanase) significantly increased on host plants than untreated control. The high β 1, 3 Glucanase activity was increased from six to eight days.
18. Protein profiling showed unique induced bands found in this experiement, 15.2 KD was unique induced with the application of Citrullus colocynthis, 26.5 and 44.5 KDs observed only for P. oxalicum. Induced bands found in bioagents P. oxalicum, S. cerevisiae and P. chrysogenum at 91, 66, and 62.5 KDs.
19. Exo-1, 4-β- glucanase (C1), and Endo-1,4-β- glucanase (Cx) activities of T. viride and Penicillium chrysogenum, showed the highest level production. Pectinase activity of Penicillium chrysogenum No. 1, Penicillium oxalicum, and Trichoderma viride gave ability of pectinase production, while S. cerevisiae No1 showed no pectinase activity.
20. The main components of aqueous extract of C. colocynthis were determined and identified using gas chromatography-mass spectrometry (GC-MS). Extracellular metabolites resulted in ten main compounds which constituted 58.66% of the total analyses.
21. The most intensive component in aqueous extract of C. colocynthis was 9,12-Octadecadienoic acid (Z,Z)-(CAS); Linoleic acid; Linoleic; Unifac 6550; Linolic acid; Telfairic acid; Grape seed oil; Polylin No. 515; cis,cis-Linoleic acid; 9, 12-Octadecadienoic acid; cis-9,cis-12-Octadecadienoic acid; 9,12-Octadecadienoic acid and Squalene comprising 45.43% and 0.88% of the total analysis, respectively. 9,12-Octadecadienoic acid (Z,Z)-, 2-hydroxy-1-(hydroxymethyl) ethyl ester; Linolein, 2-mono-; .beta.-Monolinolein; 2-Hydroxy-1-(hydroxymethyl) ethyl (9Z,12Z)-9,12-octadecadienoate was the second intensive component that identified from aqueous extract of Citrullus colocynthis comprising 6.12% % of the total analysis. On the other hand, many other compounds were detected such azole derivatives, oxalic acid, 4,5,6,7-tetrachloro-3-ethoxy-1H-isoindole; 1H-Isoindole, 4,5,6,7-tetrachloro-3-ethoxy- (CAS) represented the third most intensive component in aqueous extract of Citrullus colocynthis comprising 3.02 % of the total analysis. 3-(2-methylphenoxy) pyridazine and gamma.-Tocophero also detected comprising 0.18 % and 0.83% respectively of the total analysis.