A novel tpp-like protein from Bacillus thuringiensis strain GXUN31-2 with nematicidal activity against Meloidogyne...

The plant root-knot nematode Meloidogyne spp. is an endoparasite with worldwide distribution that is detrimental to the growth of a wide range of plants. The insecticidal crystal proteins produced by Bacillus thuringiensis are widely used as a biological insecticide to control Lepidopteran, Hemiptera, and Coleopteran pests. However, there are few reports of toxicity against plant-parasitic nematodes. In this study, we report the cloning and characterization of a novel Tpp-like protein from B. thuringiensis strain GXUN31-2 that exhibits significant nematicidal activity against the plant root-knot nematode Meloidogyne enterolobii. The full-length CG_5628 gene was 951 bp and encoded a 34.4 kDa protein consisting of 316 amino acid residues. The gene was ligated into pET30a(+) and expressed in Escherichia coli BL21(DE3). Following purification of the Tpp-like protein, bioassays against the second-stage juvenile (J2) of M. enterolobii revealed lethal concentration (LC₅₀) values of 144.3 μg/ml (95 % Confidence interval: 133.5-155.7 μg/ml). Analysis of the conserved domain revealed the presence of a Ricin B lectin domain with residues located at positions 8-155. Our results indicate the potential of this protein as a new and effective nematicide.