Biocontrol efficacy of Pseudoxanthomonas japonensis against Meloidogyne incognita and its nematostatic metabolites

Abstract

The rhizosphere bacterium ZKB-2 showed strong nematostatic activity against the Meloidogyne incognita. Our study aimed to identify the nematostatic metabolites and evaluated the biocontrol efficiency in pot experiments. As bacterial culture filtrate showed 100% nematostatic activity of Meloidogyne incognita juveniles in 12 hr, we isolated and identified six compounds following activity guiding. 3-methoxycyclobutane-1, 2-dione showed 58.9% and 72.2% nematostatic activity on juveniles of M. incognita in 12 hr and 48 hr, with strong LC₅₀ value at 447 μg mL⁻¹. In pot experiments, treatments with bacterial culture filtrate of strain ZKB-2 showed significant efficacy, especially at doses of 150 mL/pot, which were close to that of avermectin (positive control) at 0.01 g kg⁻¹ soil. The most effective treatment inhibited 85.1% populations of juveniles of M. incognita in the roots and 76.9% in the rhizosphere soil after 30 days. Furthermore, tomato growth also promoting significantly increased in a dose-dependent manner. Our results revealed the potential of strain ZKB-2 to act as a biocontrol agent in the integrated management of root-knot nematode on tomatoes.

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