Reaction of different Oryza species against rice root-knot nematode, Meloidogyne graminicola

Rice (Oryza sativa) is an important cereal crop and staple food for more than half of the world population. The sedentary endoparasitic nematode Meloidogyne graminicola is one of the major biotic stress factors that limit rice production globally irrespective of the agro-ecosystem. To tackle this, the host plant resistance is given prime importance due to global awareness towards ecologically stable and environmentally safe management options. However, the availability of resistant source within O. sativa against M. graminicola is limited and hence the search was extended to its wild relatives globally. In line with that, about 24 germplasms of different Oryza species collected from the gene bank of NRRI, Cuttack were evaluated against M. graminicola under artificial inoculation condition. Among them O. eichingeri and O. grandiglumis belonging to O. officinalis species complex and O. brachyantha were found to be resistant to M. graminicola with the lowest gall index (2.0-2.3 galls /root system). Oyza rufipogon, O. officinalis and O. alta were found tolerant to the nematode while all other species exhibited susceptible to highly susceptible reaction to the nematode. A more comprehensive study is necessary to shed light on the consistency of resistance within each Oryza species and also suggest the utilization of molecular tools to decipher the resistance mechanism govern in the reported accessions against rice root-knot nematode.