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

Abstract

urvey 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.

Biological control of tomato wilt disease incited by Fusarium oxysporum f.sp lycopersici and there effects on seed germination and other biological parameters

“…Eight fungal isolates which proved pathogenic and representing different localities in different governorates,i.e.Behera,Minofiya, Ismailia and Minia were isolated from wilted tomato plants and investigated and identitied as Fusarium oxysporum f. sp.lycperisci .Pthogenicity test revealed El -Katatba isolate(Minofiya Governorate) was the most virulent (Saleh et al,2016).…”

“…Data were recorded 10, 20, 30, days after transplanting . Disease severity was recorded as mentioned before (Saleh et al, 2016).…”

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In previous paper it has been reported that Fusarium oxysporum f.sp lycopersici was the incident of Fusarium wilt disease in some Egyptian governorates (Saleh et al, 2016).This paper delt with biological control of the pathogenic fungus. Trichoderma harzianum , Trichoderma viride, Bacillus subtilis and Bacillus megaterium were isolated from rhizospher of naturally wilted infect plant and identified as abovementioned .

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“…It is commonly grown by vegetable growers word wide (Jacobs et al, 2013). Fusarium oxysporum f. sp lycopersici is an abundant in Egypt and cause severe losses in yield (Saleh et al, 2016) The soilborne tomato root infecting pathogen Fusarium oxysporum f. sp lycopersici is particularly difficult to control using standard cultural and chemical methods (chandel et al, 2009). Wilt resistant varieties of tomato are available but resistant has been overcome by the appearance of new races of the pathogen.…”