Detection of Salinity Tolerance Pseudomonas Fluorescense Isolates and their Effect on Control Fusarium Wilt Disease Caused by Fusarium Oxysporum F. Sp. Lycopersici on Tomato

Abstract

This study was conducted to obtain salinity-tolerance Iraqi isolates of Pseudomonas fluorescence. Besides, test its salinity tolerance on PDA culture media and study its effect in the control of fusarium wilt disease on tomatoes caused by the fungus Fusarium oxysporum f.sp. lycopersici. Six isolates of bacteria were isolated from areas with soils showing symptoms of salinity, their potential for salinity tolerance was tested by three concentrations of NaCl (5, 10, and 15%). In addition to their antagonistic potential against the pathogenic fungus F. oxysporum f.sp. lycopersici isolate (FO3) was also tested on a PDA medium. The isolates PO1 and PO2 were selected, which showed the potential to salinity tolerate at different concentrations of salt and the most growth-inhibiting of the pathogenic fungus F. oxysporum f.sp. lycopersici. The two isolates were partially identified using the PCR technique, and the sequence was deposited in the NCBI global gene bank, they were given Accession No. (ON041212 and ON041213). The two isolates' effect in controlling fusarium wilt on tomato plants showed efficiency in reducing the rate and severity of wilt disease. Thus, the incidence reached (13.33-85.00%) and the disease severity (10.34-80.00%) respectively, compared to the control treatment (without pathogenic fungi), which showed the incidence and disease severity amounted to (90.00 - 93.33%). Moreover, the treatment of inducing resistance showed high effectiveness with significant differences among all treatments in reducing the incidence and disease severity amounted to (10.34 - 13.33%).