The response of rice varieties to Meloidogyne graminicola from the Mekong Delta, Vietnam

Summary The rice root-knot nematode, Meloidogyne graminicola , is a serious pathogen of rice production worldwide. In Vietnam, scientific information on the rice root-knot nematode is limited. In this circumstance, our study aimed to investigate the characteristics of M. graminicola from rice fields in southern Vietnam and to evaluate the reaction of 20 rice varieties to this soil-borne pathogen in a glasshouse experiment. Ten populations of root-knot nematode collected from rice fields at different geographical regions in the Mekong Delta were identified as M. graminicola based on the perineal configuration of females and species-specific molecular markers. The morphological, morphometric and molecular characteristics of ten nematode isolates were defined, and the variations observed between these isolates were not significantly different. The pathogenicity of these isolates was examined in the susceptible Indica rice, Oryza sativa ‘IR64’, with a reproduction factor ranging from 18.1 to 37.8. Of the 20 Indica rice varieties tested in response to the nematode population MG-PN08, the ‘Tetep’ variety showed moderate resistance to the nematode (reproductive factor = 11.7; galling index = 2.4), while others were ranked at levels ranging from moderately susceptible to highly susceptible. The life cycle of M. graminicola in ‘Tetep’ root is 28 days compared to 21 in ‘IR64’. ‘Tetep’-nematode interaction at the histological and molecular levels needs further investigation to develop new rice varieties resistant to rice root-knot nematode.