Phylogenetic position of Xiphinema oxycaudatum (Nematoda: Longidoridae) associated with maize using 28S rDNA from South Africa

Plant-parasitic nematodes are the main nematodes that live in the soil, causing yield loss in various crops. Since Xiphinema oxycaudatum is an ectoparasite, it can reduce crop yields by feeding on the roots of crops like maize. Correct identification of this species is crucial as maize is a vital crop in South Africa’s Limpopo Province. Therefore, this molecular study was conducted in 2023 at Limpopo University to identify the nematode from South Africa’s soils using 28S rDNA marker. The recovered nematode was extracted using the tray method, and then its DNA was extracted using the chelex method. The nematode was identified as Xiphinema. Afterward, 28S rDNA was amplified using specific primers to identify the nematode at the molecular level. The Nblast analysis based on the large subunit ribosomal DNA showed South African X. oxycaudatum had 99% similarity (MK966417) with the South African population. Phylogenetic analysis using maximum likelihood placed this species with those molecularly identified as X. oxycaudatum in the same clade with highly supported (100) bootstrap values. While 28S rDNA was used to successfully identify this species, further investigation into the phylogeny of X. oxycaudatum will benefit from the addition of other rDNA markers such as ITS rDNA and mitochondrial DNA.