First Report of Meloidogyne haplanaria Infecting Mi-Resistant Tomato Plants in Florida and Its Molecular Diagnosis Based on Mitochondrial Haplotype

Abstract

Meloidogyne haplanaria is a species originally found infesting peanut in Texas and, more recently, in Arkansas. In this study, we confirmed the presence of M. haplanaria in Florida based on morphological and molecular characterization. This species was identified from a sample submitted for diagnosis collected from Mi-resistant tomato rootstock grown in Naples, FL. The major diagnostic criteria to distinguish M. haplanaria from other closely related root-knot nematode (RKN) species are based on morphological differences and host range tests, which are time consuming and labor intensive and require living or well-preserved specimens. In our study, we provide an easy diagnostic strategy to distinguish M. haplanaria from other RKN species based on amplification of two mitochondrial DNA regions. These regions span the intergenic spacer and part of the adjacent large subunit ribosomal RNA gene (lrDNA) and sequence polymorphisms in lrDNA revealed by the restriction pattern following digestion with the restriction enzymes HinfI and MnlI. A unique haplotype pattern, which has not been observed in any of the RKN species described thus far, was observed in M. haplanaria. The outcome of molecular analysis of M. haplanaria aligned with morphological measurement and characteristics as well as perineal pattern originally described for M. haplanaria.