Endophytic Bacteria from Solanum nigrum with Plant Growth-Promoting and Fusarium Wilt-Suppressive Abilities in Tomato

Abstract

Fifteen endophytic bacterial isolates from Solanum nigrum and S. nigrum var. villosum stems were screened for their plant growth-promoting potential and antifungal activity against Fusarium oxysporum f. sp. lycopersici (FOL). Isolates SV65, SV68 and SV109 were the most efficient in controlling the development of the disease (77-92%) and in improving tomato growth (32-62%) compared to the controls. They were characterized and identified by using 16S rDNA sequencing genes as being Bacillus amyloliquefaciens subsp. plantarum for the strain SV65 (KR818073) and B. methylotrophicus for the two strains SV68 (KR818074) and SV109 (KR818076). Gas Chromatography-Mass Spectrometry analysis of the n-butanol extract from B. amyloliquefaciens subsp. plantarum SV65 matched phthalic acid, mono(2-ethylhexyl)ester as major compound. The bacterium B. amyloliquefaciens subsp. plantarum SV65 and B. methylotrophicus SV109 were shown to be chitinase-, protease-, pectinase-, phosphatase-, and indole 3-acetic acid (IAA)-producing agents. Furthermore, B. methylotrophicus SV68 produced chitinase, pectinase, and IAA (28.49 µg/ml), and B. amyloliquefaciens subsp. plantarum SV65 excreted siderophores andoxalic and malic acids. This study demonstrates that S. nigrum and S. nigrum var. villosum can be potential plant species for isolation of endophytic bacteria serving as biocontrol and biofertilizing agents for the improvement of production of tomato grown in FOL infested and noninfested soils.

Keywords

• Bacillus spp.
• biocontrol
• Fusarium oxysporum f. sp. lycopersici
• metabolites
• Solanum nigrum
• tomato growth