52 endophytic strain Hypoxylon serpens isolated from tobacco stimulated the
flowering process of the host. In this research high plant heights, stem diameters, plant fresh weight,
plant dry weight, root length, number of fruit that developed in the tomato plants was generally increased in endophyte treated plants. All the endophytic fungi
isolates were found to be effective in stimulating growth parameters and their effect in growth stimulation differed significantly at p0.05 according to Duncan
Multiple Range Test.
4.2.5 Antibiosis
In vitro Test
The potential of endophytic fungi to suppress RKN is supported by the observation that endophytic fungi antagonize RKN in vitro. The fact that culture
filtrate in this study was free of spores and mycelia strongly imply that compounds in the culture filtrate were toxic to RKN juveniles indicating that the
major mechanism of action by endophytic fungi against RKN juveniles was antibiosis. Endophytic fungi that resulted in consistently high juvenile mortality
rates included; Nigrospora sp, isolate XP9, Fusarium oxysporum, Fusarium chlamydosporum
, Chrysosporium sp, Trichoderma hamatum, Trichoderma pseudokoningii,
Sterile black 1. Results obtained from this study were considered to determine the mechanism of action of endophytic fungi against RKN. It has
been demonstrated before that Fusarium sp can produce toxic secondary metabolites such as Zearalanone, fummonisins, tricothecenes and fusaric acid
Vey et al. 2001. Hallmann Sikora 1994a; Hallmann Sikora 1994b demonstrated that culture filtrate of an endophytic F.oxysporum isolated from
tomato roots reduced mobility of M. incognita within 10 minutes of exposure. Production of 3-hydrxypropionic acid 3-HPA in culture by endophytic fungi
isolated from above ground plant organs has been demonstrated by Schwarz et al. 2004. It was further demonstrated by Ciancio 1995 that
mycotoxins produced by endophytic fungi such as T2-toxins, moniliformins, verracarin A, vytochalasin B and Enniatin B caused significant mortality of
Meloidogyne javanica Treub Chitwood juveniles in the laboratory. As expected
in vitro test results indicated that Juvenile mortality increased with increase in
53 concentration of culture filtrate and with increase in time of exposure of the
juveniles to culture filtrate concentration.
4.2.6 Correlation between In vitro Test and In planta Test
Studies on the relation between in vitro and in planta activities are very useful to compare the mechanisms between in planta and in vitro test for this
reason a correlation analysis was performed to examine the relationship between in vitro
and in planta activities of the endophytic fungi. There was a similar pattern between percentage juvenile mortality rate at 30 culture filtrate
concentration with percentage root gall reduction and juvenile mortality rate at 30 culture filtrate concentration with percentage egg mass reduction, this
indicated a similar mechanism of action by endophytic fungi in suppressing RKN both in vitro and in planta tests,. Some papers have stated a strong correlation
between in vitro and in planta tests indicating similar mechanisms of actions between in vitro and in planta tests Hultberg et al. 2000 Figure 7.
Figure 7. General correlation showing effect of endophytic fungi treatments on reduction of root gall formation a and egg massformation in
comparison to juvenile mortality rate at 30 culture filtrate concentration after 24 hours
54
V. CONCLUSION AND RECOMMENDATION
5.1 Conclusion
1. Exploration resulted to a total of 12 isolates that is: Torula sp, Ulocladium
sp, Fusarium sp3, isolate XP9, Nigrospora sp, Chrysosporium sp, Fusarium oxysporum, Fusarium chlamydosporum,
Trichoderma hamatum, Trichoderma pseudokoningii,
Sterile black 1, Sterile black 2. Most potential endophytic fungi were obtained from healthy tomato plants in
lowland areas. 2.
Most effective endophytic fungi isolates in suppressing root-knot nematodes as well as promoting plant growth performance were isolate
XP9, Nigrospora sp, Chrysosporium sp, Fusarium oxysporum, Fusarium chlamydosporum,
Trichoderma hamatum, Trichoderma pseudokoningii, Sterile black 1, Sterile black 2.
3. Mechanism involved by the endophytic fungi in suppression of root knot
nematodes is antibiosis, induced resistance could also be another method involved but was not investigated in this research.
4. Endophytic fungi play important role in mediating resistance of tomato
plants in the field, because species composition and diversity of endophytic fungi in healthy plants in the field was different from species
composition and diversity of endophytic fungi in nematode infected plants.
5.2 Recommendation
1. Further tests should be conducted to investigate the type of toxins
produced by endophytic fungi against RKN in vitro. 2.
More research should be conducted to investigate the mechanisms by which endophytic fungi promote plant growth in planta.
3. More investigations should be conducted to determine the mechanisms of
induced resistance involved by isolate XP9, Nigrospora sp, Chrysosporium
sp, Fusarium oxysporum, Fusarium chlamydosporum, Trichoderma hamatum and Trichoderma pseudokoningii,
in RKN suppression.
