Molecular characterisation of reniform nematodes of the genus Rotylenchulus Linford & Oliveira, 1940 (Rotylenchulidae, Tylenchida).

Abstract

Reniform nematodes of the genus Rotylenchulus comprise a few species, which kidney-shaped mature females are semi-endoparasitic on roots. These nematodes are widely distributed across tropical and subtropical regions of the world and associated with numerous agricultural and horticultural crops. Nematode surveys of plant-parasitic nematodes undertaken during the last years in several crops including sugarcane, sorghum, maize, grapevine and wild and cultivated olives in Italy, South Africa, Spain and USA revealed heavy soil infestations by several reniform nematodes, including Rotylenchulus clavicaudatus, R. leptus, R. macrosoma, R. macrodoratus, R. reniformis, R. sacchari and an unknown species parasitizing sugarcane in South Africa. These species were characterized and differentiated from each other using the D2-D3 of 28S rRNA, ITS rRNA, hsp90 and coxI mtDNA gene sequences. In this study we also provided phylogenetic relationships within Rotylenchulus as inferred from the Bayesian analysis of these genes. PCR with species-specific primers was developed for rapid and accurate diagnostics of the pathogenic species R. reniformis. Sequence and phylogenetic analysis revealed two distinct and divergent paralogs of rRNA genes for R. reniformis and an unknown Rotylenchulus species.