Meloidogyne vitis infecting mulberry (Morus alba L.) in Yunnan, China: morphology, molecular identification, and pathogenicity

BACKGROUND: Mulberry is an economically important sericulture crop; however, infection by root-knot nematodes (RKNs) poses a serious threat to its production. We observed a high density of RKNs parasitizing mulberry in Yunnan, China. To identify the pathogenic species, we characterized the nematode using morphometric analysis, rDNA/mtDNA-based phylogenetics, and SCAR-PCR. Subsequently, we artificially inoculated healthy mulberry seedlings with second-stage juveniles (J2s) to assess their pathogenicity. RESULTS: The perineal pattern of females is round to ovoid, featuring a moderately high dorsal arch and two large, prominent phasmids, similar to that of Meloidogyne vitis. The morphological and morphometric traits of females, J2s, and males were consistent with those of M. vitis. Genetic analyses further confirmed this, as the rDNA (ITS1-5.8 S-ITS2) and mtDNA (coxI and coxII) sequences showed > 99% similarity to M. vitis and clustered within the same clade with high support (99%-100%). Moreover, species identity was further confirmed using M. vitis-specific primers Mv-F/R, and a single specific fragment of 174 bp was obtained. Artificial inoculation demonstrated that the RKN isolated from mulberry could complete its life cycle in the roots of healthy seedlings of mulberry, producing typical root-knots and egg masses. CONCLUSIONS: The RKN parasitizing in mulberry was confirmed as M. vitis based on the morphological features and molecular results. This is the first report of M. vitis attacking mulberry. M. vitis is capable of infecting and damaging mulberry, posing a potential threat to mulberry production. The results of this study providing a theoretical basis for accurately identifying and implementing future effective and integrated nematodes management strategy to safeguard mulberry cultivation.