Molecular Variations among some Isolates of Fusarium oxysporum f.sp lycopersici and Response of Different Tomato Cultivars and Seedling Age to Infection

Document Type : Original Article

Authors

1 Plant Pathol. Dept., Fac. Agric. El-Minia Unv., Egypt

2 Plant Pathol. Res. Inst., Agric. Res. Centre, Giza, Egypt

Abstract

Survey of tomato wilt was carried out through two successive
growing seasons (2013 and 2014) in farms' located at 4 sites
belonging to four Egyptian Governorates (Behera, Minofiya, Ismailia
and Minia). The disease incidence in these sites ranged between 14.3
in Ismailia Governorate and 37.5% in Minofiya Governorate. Isolation
on Potato Agar medium from naturally infected plants collected from
some Egyptian Governorates resulted in obtaining many fungal
isolates that proved to be pathogenic to tomato Super-Strain B cultivar
on pathogenicity test.The agent responsible for wilt of tomato in
Egypt was identified as Fusarium oxysporum. The pathogenic
capabilities of eight fungal isolates representing different localities in
different Governorates, i.e. Behera, Minofiya, Ismailia and Minia
were investigated., Pathogenicity test using eight isolates of Fusarium
oxysporum isolated from naturally infected tomato plants showing
typical symptoms of wilt revealed that they were all able to cause wilt
symptoms on different tomato cultivars. In this respect, isolate of
F. oxysporum isolated from El-Khatatba, Minofiya Governorate was
the most virulent that induced the disease in tomato plants. Ten plant
species were evaluated for their reactions to infection with the most
virulent isolate, El-Khattba (Minofiya Governorate). The RAPD-PCR
of the DNA analysis using 10-mer primer of eight isolates of
F. oxysporum f.sp. lycopersici collected from different Governorates
showed variations in DNA pattern. To test their response to infection
with this isolate, ten tomato cultivars were evaluated to infection by
the most virulent isolate (isolated from El-Khattba, Minofiya
Governorate) and the results indicated that cv. Super-Strain B was the
highest susceptible, whereas cv. Super-Marmand was the lowest one.
Moreover, effect of tomato seedlings age of Super-Strain B (highly
susceptible) and Super-Marmand (low susceptible) on infection by the
most virulent isolate of the pathogen was tested.

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