Antagonist effect of native bacteria of the genus Bacillus on the root-knot nematode (Meloidogyne spp.) in tomato germplasm

The root-knot nematode (Meloidogyne spp.) causes losses of up to 68% of tomato (Solanum lycopersicum L.) production, management practices are limited and toxic chemicals are mostly used. An integrated management alternative was evaluated based on the antagonist effect of native bacteria of the genus Bacillus on the nematode using four tomato germplasms, two commercial (susceptible and tolerant) and two wild (IAC 1687 and COLY 007). In the in vitro phase, strains B. infantis (GIBI 177), B. altitudinis (GIBI 187), B. pumilus (GIBI 195), B. amyloliquefaciens (GIBI 200) and B. pumilus (GIBI 206) were evaluated and the percentage of inhibition of nematode egg hatching at 9 d after inoculation and the percentage of mortality in juveniles at 72 h after incubation were determined. The results showed that all native strains presented a control effect under controlled conditions, but B. infantis being the bacterium with the highest selection index (0.65). In the field phase, a split-plot design was established, the main plot being the four-tomato genotype and the secondary plot the bacillus strain, and the percentage of severity, number of eggs and juveniles were evaluated. The tomato genotype with the best response to Meloidogyne spp. attack was IAC 1687, when obtaining values of 2088.8 & PLUSMN; 599.1 individuals 100 g-1 root. The bacterium that presented the best interaction with 3 of the 4 genotypes evaluated was B. pumilus (GIBI 206), in IAC 1687 with 1731.33 & PLUSMN; 1382. 57 individuals 100 g-1 root, in the resistant genotype with 16627 & PLUSMN; 4588.1 individuals 100 g-1 root and in the susceptible genotype with 3303.83 & PLUSMN; 1256.25 individuals 100 g-1 root. This study reports the use of tomato genetic resources and antagonist bacteria as a potential integrated management of the root-knot nematode.

Automated summary

This study evaluated the antagonist effect of native Bacillus bacteria on the root-knot nematode in tomato plants. The results showed that all tested Bacillus strains had a control effect on the nematode under controlled conditions, with B. infantis being the most effective strain. In the field, the tomato genotype IAC 1687 showed the best response to nematode attack, and B. pumilus (GIBI 206) had the best interaction with the evaluated genotypes. This study highlights the potential of using tomato genetic resources and antagonist bacteria for integrated management of root-knot nematode.