Molecular identification of plant pathogenic Meloidogyne species in Sri Lanka

Abstract

Molecular Identification of the Plant Parasitic Nematode, Meloidogyne Species in Sri Lanka Abstract Root-knot nematodes, a major type of plant pathogen of the genus Meloidogyne, cause substantial losses in many agricultural crops. Therefore, the correct identification of Meloidogyne species is essential for the application of appropriate nematode control measures for effective crop recovery. In this study, molecular identification of Meloidogyne species was conducted on 27 root samples with abnormal root-galls, collected from nine different types of crops. The samples were collected from 21 different agricultural fields in seven provinces of Sri Lanka, between 2014 - 2018. The presence of juvenile stages in 25 samples (93%) was confirmed using microscopic analysis, and DNA was isolated from purified males, eggs, and juvenile stages for molecular identification. Universal primers MF/MR, which amplified the 500 bp of ribosomal DNA, confirmed the presence of Meloidogyne in 23 samples (85%). Primers C2F3/1108 and 194/195 were used to confirm species-specific amplification of mitochondrial and ribosomal DNA. Species Meloidogyne arenaria, Meloidogyne enterolobii, and Meloidogyne thailandica were identified in 22%, 67%, and 4% of the samples collected, respectively, either as single species populations or as mixed populations. Collectively, these species were detected in several economically important crops, including tomato, cherry tomato, spinach, guava, chili, cabbage, and capsicum. Meloidogyne enterolobii was the most prevalent species and was detected on guava, capsicum, and tomato in the Northwestern, Central, and Western provinces. To the best of our knowledge, this is the first study on molecular identification of Meloidogyne species in Sri Lanka and the first report of M. enterolobii and M. thailandica in Sri Lanka. This expands the previously known worldwide distribution of these species. The presence of Meloidogyne species associated with economically important crops was observed in all seven provinces surveyed, indicating an urgent need for the implementation of effective nematode management strategies.