الفهرس 
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Abstract
Tomato Lycopersicum esculentum Mill is considered one of the
most important vegetable crops grown for human consumption. This
crop has an increasing importance now days especially in those
countries with rapidly expanding population, e.g., Africa and Asia,
where tomato production has duplicated three times since 1990
(CABI ,2011). Tomato known as one of the crops to be infected
particularly with Fusarium pathogen. Fusarium oxysporum f. sp.
lycopersici, represented a real threat to tomato production all over the
world. This study included : investigation the virulence of 15 isolates
of Fusarium oxysporum f. sp. Lycopersici collected from 5
governorates of Delta Egypt, evaluation of 5 tomato cultivars to this
fungus, characterization of these isolates for presence and absence of
genes SIX1, SIX2, SIX3, SIX4, SIX5, SIX6, SIX7 and SIX8 using
molecular technique based on PCR polymorphism analysis , capability
of the tested Fusarium isolates to produce Fusaric acid under in vitro
conditions through using High Pressure Liquid chromatography
(HPLC) analysis , relation between Fusaric acid accumulation and the
aggressiveness of Fusarium isolates toward tomato plants and
evaluation of three Trichoderma spp. and two bacterial bio-agents in
controlling the pathogen in vitro and the disease in vivo.
The obtained results illustrate the following data:
1- All the fifteen isolates were pathogenic toward tomato plants and
caused symptoms corresponding to the Fusarium wilt disease.
Moreover, results revealed that the tested isolates varied regarding
to their aggressiveness and virulence potential under the bioassay
conditions.
2- The highest percentage of disease severity i.e. 61%; 52%; 44%; and
41.65% were recorded within isolates 4 , 5,15, 2, respectively. On
the other hand, isolates 8, 12 and 14 resulted in the lowest disease
severity percentage on tomato plants (8.79%; 9.70% and 9.79%,
respectively).
3- Evaluation of five tomato cultivars revealed that the cultivar Super
Strain B showed moderate response to the wilt pathogen of tomato,
While Yara and Super Marmande cvs. were highly susceptible.
The other tomato cvs. were in between in this regard.
4- The results showed that amplicons of SIX1 were detected with all
tested isolates except isolates 8, 12, 14 and 15 in addition to the
nonpathogenic isolate, Fo162. Also,amplicons of SIX5 were
detected only within isolates 2, 3, 4, 5, 7 and 15. Additionally,
amplicons of Six6 were detected within all pathogenic tested
isolates except isolates 1, 6, 7, 8, 11 and 12. In contrary, no
amplicons for SIX2, SIX3, Six4, SIX7 and Six8 were detected
among all Fusarium oxysporum isolates subjected to the test..
5- The present study suggests that the presence of SIX1, SIX5 and
SIX6 genes within Egyptian isolates of Fusarium oxysporum f.sp.
lycopersici can be used, for some extent, as a remarkable indicator
for virulence potential on tomato plants under certain conditions.
6- Regarding with fusaric acid accumulation, results of 4 weeks after
inoculation demonstrated that the highest amounts of FA were
13000, 11101, 6559 and 3936 mAU*S of isolates 4, 8, 6 and 10
respectively. While the higher amounts of FA at 6 weeks post
inoculation were 22926, 12136, 10991 and 10451 mAU*S, of
isolates 3, 2, 4 and 12, respectively. On the other hand, the highest
amounts of FA at 8 weeks post inoculation were 60816, 42926 and
37275 mAU*S of isolates 8, 12 and 4, respectively.
7- HPLC chromatogram analysis illustrates that,
A- At 4 weeks post inoculation, in -spite of the highest disease
severity was recorded with isolates 12, 3, 4 while only
isolate 4 showed relative high ability to produce high
concentration of FA comparing to the other isolates .
B- At six weeks after inoculation, the results showed that the
most virulent isolates were 12, 2, 3, and 4 produced the
highest concentrations of FA comparing to the other
isolates.
C- At eight weeks post inoculation, the results showed that
among the most virulent isolates (12, 2, 3 and 8) only two
isolates, 12 and 8 recorded relative high FA accumulation,
while the other two isolates 2, and 3 exhibited relative low
FA producing capability comparing to other isolates .
8- Regarding to the accumulation of total secondary metabolites
within the tested Fusarium isolates, the chromatogram analysis
indicated that,
A- The highest concentrations of total secondary metabolites were
observed with isolates 8, 4, 7 and 1, respectively at four weeks
post inoculation.
B-At six weeks post inoculation, the highest concentrations of total
secondary metabolites were 48654, 34517 and 26511 mAU*S
which recorded with isolates 10, 11 and 12, respectively (Figure
12).
C- At 8 weeks post inoculation, showed that isolates 4, 12, 11 and
1 produced the highest total secondary metabolites expressed as
91904, 89328, 49585, 42268 mAU*S, respectively (Figure 12).
9- The present study illustrate that the all tested Egyptian Fusarium
oxysporum isolates are able to produce FA mycotoxin under the
test conditions. It seems and for some extent, FA plays a
distinctive role in the Fusarium wilt disease development on
tomato plants during the middle and last stages of infection while
this role is almost missing at the primary infection stage.
10- Further studies focus on fractionation, purification and
identification of some novel distinguish secondary metabolites
which are accumulated within FA are highly needed to figure out
whether FA alone or combined with other substances can be
involved in the interactions between Fusarium oxysporum
pathogenic isolates and their host plants.
11- Regarding biological control study, the obtained results showed
that all the tested bio-agents showed low to moderate effect in
suppressing radial growth of the pathogenic fungus.
12-The bacterial bio-agents isolate of B. subtilis and P. fluorescens
was more effective than Trichoderma spp either in vitro or in vivo.
13-Both the healthy and oxidore fungicide enhanced the growth
parameters (length of plants; length of root and fresh weight and
dry weight) rather than the fungal / bacterial antagonists
investigated compared to the control.