Population diversity of Pasteuria penetrans from pepper fields and its genetic variation from single root-knot nematodes

Pasteuria penetransis an obligate parasite of root-knot nematodes. Pepper ( Piper nigrum) is one of the main economic crops in Hainan Island, China, and the incidence of root-knot diseases is high. The Pasteuriasamples from 20 pepper fields of seven counties in Hainan Island were identified, and the results suggested that there were various P. penetranspopulations in the same field but no obvious specificity among different regions. However, five strains appeared to be potentially novel species of the genus Pasteuriaby 16S rRNA gene sequence analysis. Additionally, further study showed that a single nematode of Meloidogyne incognitaand of M. javanicacould be infected by different strains of P. penetrans, and the genetic diversities of P. penetransbetween two different host species were found only in gyrBrather than 16S rRNA and sigEgene sequences. These findings will provide some theoretical underpinning for the research of obligate parasitism mechanism between root-knot nematodes and P. penetrans.