Abstract
Fusarium crown and root rot (FCRR) is a serious tomato disease in Tunisia which is difficult to control due to its soilborne nature and to the luck of genetic resistance. In the current study, native Solanum linnaeanum was explored as potential source of effective fungal agents for disease biocontrol. Eight fungal isolates, recovered from S. linnaeanum plants growing in the Tunisian Centre-East and shown able to colonize roots, crowns and stems of tomato (Solanum lycopersicum L.) seedlings, were tested for their ability to inhibit Fusarium oxysporum f. sp. radicis-lycopersici (FORL), the causal agent of this disease, and to promote plant growth. Tomato seedlings inoculated or not with FORL and treated using tested fungal isolates, exhibited significant increments in their growth parameters. Tested as conidial suspensions or cell-free culture filtrates, I74 and I92 isolates were the most active leading to 92.8% decrease in FCRR severity and 89.3 to 95.2% lowered vascular browning extent as compared to FORL-inoculated and untreated controls. These two isolates were microscopically and macroscopically described and identified using rDNA sequencing gene as being Penicillium crustosum I74 (MF188258) and Fusarium proliferatum I92 (MF188256). Pathogen mycelial growth was inhibited by 29.4 to 78.1% using their conidial suspensions and by 67.5 to 82% with their cell-free culture filtrates. P. crustosum I74 and F. proliferatum I92 showed chitinolytic, proteolytic and amylase activities. Only I92 isolate exhibited a lipolytic activity. Our study clearly demonstrated that I74 and I92 isolates were promising candidates for suppressing FCRR severity and promoting tomato growth. Further investigations are required for elucidating their mechanisms of action involved in disease suppression and plant growth promotion. Key words: Antifungal activity, associated fungi, Fusarium oxysporum f. sp. radicis-lycopersici, Solanum linnaeanum, tomato growth.
Highlights
Fusarium crown and root rot (FCRR) is one of the most damaging tomato diseases worldwide infecting more severely roots and crowns (Rowe and Farley, 1977)
They were affiliated to 5 genera, namely Fusarium, Alternaria, Penicillium, Aspergillus, and Trichoderma based on their macro- and micro-morphological traits
To the best of our knowledge, S. linnaeanum was firstly reported in the current study as a potential source of isolation of endophytic fungi with antifungal potential against FORL
Summary
Fusarium crown and root rot (FCRR) is one of the most damaging tomato diseases worldwide infecting more severely roots and crowns (Rowe and Farley, 1977). Severe disease outbreaks may lead to quick plant dieback and induce serious crop and yield losses (Hibar et al, 2006; Ozbay and Newman 2004; Can et al, 2004). This pathogen is difficult to suppress in soil due to its airborne dissemination to neighboring plants and to its long survival in soils as chlamydospores even in absence of host plants (Rowe and Farley, 1977). The limited effectiveness of chemical fungicides and the lack of resistance in the most commercially grown tomato cultivars led to increased focus in the search for other effective alternatives such as biological control. A significant decrease, by 50 to 73% in FORL radial growth, was achieved using some biofungicides and natural greenhouse conditions, Hibar et al (2006) succeeded in decreasing disease FCRR incidence to 5.5% using biofungicide based T. harzianun strain T22
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
