Bacillus halotolerans strain LYSX1-induced systemic resistance against the root-knot nematode Meloidogyne javanica in tomato

Abstract

Purpose Determination of the nematicidal potential and mode of action of bacteria isolated from tobacco rhizosphere soil against the root-knot nematode Meloidogyne javanica in tomato plants. Methods Antagonistic bacteria were isolated from rhizosphere soil of tobacco infested with root-knot nematodes. Culture filtrate was used to examine nematicidal activity and ovicidal action of bacterial strains. Biocontrol of M. javanica and growth of treated tomato plants were assessed in pot experiments. To clarify whether secondary metabolites of bacteria in tomato roots induced systemic resistance to M. javanica, bacterial culture supernatants and second-stage juvenile nematodes were applied to spatially separated tomato roots using a split-root system. Bacterial strains were identified by 16S rDNA and gyrB gene sequencing and phylogenetic analysis. Results Of the 15 bacterial strains isolated, four (LYSX1, LYSX2, LYSX3, and LYSX4) demonstrated nematicidal activity against second-stage juveniles of M. javanica, and strain LYSX1 showed the greatest antagonistic activity; there was dosedependent variability in nematicidal activity and inhibition of egg mass hatching by strain LYSX1. In vivo application of LYSX1 to tomato seedlings decreased the number of egg masses and galls and increased the root and shoot fresh weight. Treatment of half of the split-root system with LYSX1 reduced nematode penetration to the other half by 41.64%. Strain LYSX1 was identified as Bacillus halotolerans. Conclusion Bacillus halotolerans LYSX1 is a potential microbe for the sustainable biocontrol of root-knot nematodes through induced systemic resistance in tomato.

Biocontrol of Wheat Crown Rot Using Bacillus halotolerans QTH8

“…Moreover, culture filtrates of bacterial strain QTH8 demonstrated antagonistic potential against Heterodera glycines , Meloidogyne javanica , and M. incognita (data not shown). Similar findings have been documented by Xia et al (2019), who found broad-spectrum activity of B. halotolerans LYSX1 against diverse plant pathogens [ 31 ].…”

“…The outcomes from the glasshouse environment indicated that the application of QTH8 improved the growth parameters of wheat seedlings (root length, plant height, and fresh plant weight) and reduced the severity of the disease caused by F. pseudograminearum . Several research groups have reported similar findings [ 17 , 18 , 19 , 31 ]. However, it is essential to verify the potential of QTH8 against F. pseudograminearum under field tests in future research.…”

The carB Gene of Escherichia coli BL21(DE3) is Associated with Nematicidal Activity against the Root-Knot Nematode Meloidogyne javanica

“…Many studies have reported that plant-parasitic nematodes can be controlled through active substances generated by bacteria during the fermenting process [ 7 , 11 , 13 , 17 , 27 , 28 , 29 , 30 ]. Specifically, several pathogenic E. coli isolates have been assessed for their ability to kill the free-living nematode C. elegans [ 19 , 20 ].…”

“…Moreover, B. thuringiensis (Bt) produces the well-known Cry protein, which displays specific toxic activity against nematodes and insects [ 15 ]. In addition, induced systemic resistance (ISR) is triggered by plant growth-promoting rhizobacteria (PGPR) [ 16 , 17 ].…”

Isolation and identification of endophytic bacteria associated with kiwifruit and their biocontrol potential against Meloidogyne incognita

“…in the world. The nematode causes gall at the root systems and impairs the absorption of water and minerals, which results in wilting, growth suppression, reduction in yield, and eventually death (Xia et al 2019). The application of non-host plants, rotation, resistant plants, flooding, and nematicides is methods for the management of plant-parasitic nematodes.…”