<i>Cis</i>-3-Indoleacrylic Acid: A Nematicidal Compound from <i>Streptomyces youssoufiensis</i> YMF3.862 as V-ATPase Inhibitor on <i>Meloidogyne incognita</i>

The application of the bionematicides derived from microorganisms and their secondary metabolites represents a promising strategy for managing root-knot nematodes. In this study, a nematicidal compound, <i>cis</i>-3-indoleacrylic acid, was isolated from <i>Streptomyces youssoufiensis</i> YMF3.862. This compound caused <i>Meloidogyne incognita</i> juveniles to have swollen bodies with apparent cracks on the cuticle surface. The LC₅₀ value of <i>cis</i>-3-indoleacrylic acid against juveniles was 16.31 μg/mL 24 h of post-treatment. <i>Cis</i>-3-indoleacrylic acid at 20 μg/mL significantly inhibited V-ATPase expression and remarkably decreased enzyme activity by 84.41%. As an inhibitor of V-ATPase, <i>cis</i>-3-indoleacrylic acid caused significant H⁺ accumulation in nematode bodies, resulting in lower intracellular pH values and higher extracellular pH values of <i>M. incognita</i>. Application of 50 μg/mL <i>cis</i>-3-indoleacrylic acid generated a 71.06% control efficiency against <i>M. incognita</i> on tomatoes. The combination results of this study indicated that <i>cis</i>-3-indoleacrylic acid can be developed as a natural nematicide for controlling <i>M. incognita</i>.