Development and Validation of LNA-Based Quantitative Real-Time PCR Assays for Detection and Identification of the Root-Knot Nematode Meloidogyne enterolobii in Complex DNA Backgrounds.

Meloidogyne enterolobii is a quarantine root-knot nematode posing a major threat to agricultural production systems worldwide. It attacks many host plants, including important agricultural crops, ornamentals, and trees. M. enterolobii is a highly virulent and pathogenic root-knot nematode species, able to reproduce on plants resistant to other Meloidogyne spp. Significant crop damage has been reported in Asia, South America, Africa, the United States, France, and greenhouses in Switzerland. To identify potential introduction pathways and ensure appropriate phytosanitary measures and management strategies, accurate detection and identification tools are needed. Therefore, two real-time quantitative polymerase chain reaction (PCR) assays based on the second intergenic spacer region of the ribosomal DNA cistron and the cytochrome oxidase c subunit I (COI) gene using locked nucleic acid probes were developed and validated for fast and reliable detection and identification of M. enterolobii. Analytical specificity was confirmed with 16 M. enterolobii populations, 16 populations of eight closely related Meloidogyne spp., and four species from other nematode genera. Optimizing and testing the assays on two real-time PCR platforms revealed an analytical sensitivity of one juvenile in a background of 1,000 nematodes and the intended limit of detection of one juvenile per 100 ml of soil. Both assays performed equally well, with the COI-based assay showing a slightly better performance concerning detection of M. enterolobii target DNA in complex DNA backgrounds.