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Abstract
ABSTRACT
Tomato is one of the most important vegetable crops, in Egypt. Unfortunately, it is a subject to several soil borne pathogenic fungi that affect its growth and production. The present study was carried out to study the pathological and melocular variability among isolates of Fusarium oxysporum f.sp. lycopersici and Rhizoctonia solani on tomato roots.
The pathogenicity tests were performed for the isolates F. oxysporum lycopersici and R. solani which isolated from samples collected from El-Gharbiya, El-Qalubia, Beni-Sueif, El-Nubaria, South Tahrir, Kafr El-Sheikh, El-Salhiya, Giza, Al-Arish, El-Ismailia, Sohag and El-Fayoum governorates on the tomato cv. Castle Rock. The result showed that all isolates were pathogenic, with different degrees of pathogenicity.
The anstomosis grouping test which conducted on the R. solani divided the tested isolates into AG-4 and AG-5.
The electrophoretic study of F. oxysporum lycopersici had high degrees of similarity and no relation between the protein profiles and the geographic source, whereas the protein profiles of R. solani placed the tested isolates in two groups. The first was El-Salhyia while the second group included the rest isolates.
The fingerprinting technique with DNA through using RAPD-PCR showed that there was, no clear relationship between genetic and geographic origin.
In vitro tests of carbon and nitrogen sources on the growth of F. oxysporum f.sp. lycopersici and R. solani showed that sucrose was the best carbon source assimilated by both fungi while sorbitol was the least one. On the other hand, sodium nitrate was the best nitrogen source while ammonium tartarate was the least assimilated nitrogen source by both fungi.
Differences in the activity of some enzymes were observed in the infected tomato tissues and fungal filtrates of the tested isolates indicating some possible degrees of physiological differences among the target isolates.
Histopathological studies indicated a similarity in the infection and development of F. oxysporum lycopersici isolates which reached to the vesicle bundle of tomato roots while R. solani isolates did not reach the vesicle bundle.