الفهرس 
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Abstract
SUMMARY
The main aim of the present thesis was to study, under laboratory conditions, the induced mechanism( of resistance of French bean to F.solani f.sp.phaseoli (the causal pathogen of root and hypocotyl rot disease of beans). The normal
(not induced) mechanisms of resistance of beans to this disease were also considered. Furthermore, the mechanisms of disease resistance to. bean anthracnose caused by C.lindemuthianum were also investigated for comparison.
The main methods of the study were :
1.Inoculation of excised bean hypocotyls (of five different cultivars) by the droplet technique and incubation at
20e’ and ..Y).C.
2.Morphological observations of the host reactions for
30 days.
5. Observations of the histopathologicai interactions at
the inoculation sites (the epidermal and outer cortical layers) of the most resistant and most susceptible
interaction systems.
4.Analyses by thin layer chromatography of the extracts
of the inoculated hypocotyls, 2, 4, and 7 days after inoculation, and also the extracts of the uninoculated
(control) hypocotyls.
5.Bioassays of the isolated compounds on the develope,i
TLC plates for the detection of antifungal compounds.
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6. The spectrophotometrical analysis of the detected phytoalexin(ii and the constitutive antifungal phenolic
compound(d.
At 20°C, bean hypocotyls of cv. Contender showed susceptibility to infection by either of the used pathogens; whereas those of cv. Swiss Blanc were resistant, but hypocotyls of cvs. Giza 3 , Giza 4, and Canadian Wonder showed different
susceptibilities.
At 30°C, hypocotyls of cv. Contender, inoculated with F.solani f.sp.phaseoli, showed intermediate reaction tending towards susceptibility; whereas those of cvs. Swiss Blanc, Giza 3 , Giza 4 and Canadian Wonder, inoculated by the same pathagen., showed varios degrees of resistance.
Hypo.cotyls of all bean cultivars, insculated with C.lindemuthianum and incubated. at 307C, showed resistance
reactions..
At 30 C, resistance to these two pathogens were induced, in general, in inoculated hypocotyls of all bean cultivars.
It can be concluded that the incubation of flamxilia-or Colletotrichum—inoculated bean hypocotyls at 301°C favours the induction of resistance of bean hypacatyl cells to these fungal. pathogens. Resistance and induced resistance of
bean hypocotyl. celia were expressed by, one (or more) of three mechanisms; namely, hypersensitivity, wall alterations or possibly phytoalexin(6 accumulation.