High Throughput Screening of Introgression Lines of Rice for Resistance against Rice Root-Knot Nematode (Meloidogyne graminicola Golden & Birchfield)

The rice root knot nematode (RRKN), Meloidogyne graminicola is the dominant biotic constraint in rice worldwide. Host plant resistance is an eco- friendly and cost-effective means to mitigate RRKN damage in rice. Considering the limited availability of genetic resources in the Asian rice (Oryza sativa) cultivars, exploration of novel sources and genetic basis for RRKN resistance is necessary. In the present study, we screened 126 diverse rice accessions (Introgression lines) of Pusa 44/O.rufipogon, to identify resistance to M. graminicola. Overall, seven resistant accessions (based on nematode gall number and multiplication factor/MF < 3) were identified and used for nematode development study. Analysis of rice accession showed very strong correlation (r=0.8414, P<0.05) between multiplication factor and number of galls in pluronic gel experiment. Among the tested rice accessions, PB1121 and SGW-141 displayed the highest multiplication factor (38.27 and 33.59) whereas, SGW-57 and SGW-56, were lowest (2.26 and 2.48). Further examination of nematode development suggested that M. graminicola penetrated less often into highly resistant varieties and more frequently failed to develop into mature females as compare to susceptible rice. The resistant accessions found in the present research would be useful for breeding and developing practical nematode management measures.