Genomic regions linked to reniform nematode (Rotylenchulus reniformis) resistance in castor

Reniform nematode (Rotylenchulusreniformis) infects castor and makes it vulnerable to vascular wilt and root rot diseases. In this study, a population consisting of 92 recombinant inbred lines (RILs) derived from the crossbetween reniform nematode resistant line JC-12 and susceptible line 48-1 was used to identifythe genomic regions linked to reniform nematode resistance. The parents, F1 and RILs were screened against reniform nematode in pot culture with artificial inoculation of nematodes. The scoring for nematode resistance was done on the basis of number of nematodes extracted from the soil at 60 days after inoculation. The mean nematode count in 48-1 and JC-12 was 215.0±9.1 and 77.8±4.8 nematodes/ml of soil wash, respectively. The F1 reaction (217.3±13.2 nematodes/ml of soil wash) was similar to the susceptible parent indicating that nematode resistance in JC-12 is recessive in nature. The nematode count in RILs ranged from 43.8 to 327.3. QTL mapping using a linkage map consisting of 1,090 SNP markers resulted in the identification one QTLeach on chromosome-6 and chromosome-8, linked to resistance. This is the first report on mapping of genomic regions linked to reniform nematode resistance in castor, which form the basis for furthering the research on genetic and molecular biology of nematode resistance in castor.