34. 
A new gene for resistance to gall midge in rice cultivar RP 2333-156-8 
      Arvind Kumar, M.N. SHRIVASTAVA and B.C. SHUKLA
      Indira Gandhi Agricultural University, Raipur492 012, M.P. India

 
     We studied the mode of inheritance of resistance to gall midge in rice cultivar RP2333-
156-8. Parents and segregating populations were screened under field conditions at Regional Agricultural Station, Bilaspur. The level of infestation was very high as the susceptible parents showed 100% infestation on single plant basis (Table 1).
     The populations from the crosses of RP2333-156-8 with susceptible parents R 2270, Ratna and Shymala segregated in the ratio of 3 resistant to 1 susceptible (Table 2) indicating that RP2333-l56-8 has one dominant gene for resistance. Their F3 progenies segregated into 1:2:1 ratio representing respectively breeding true for resistance, segregating and breeding true for susceptibility, confirming the presence of a single dominant gene for gall midge resistance in RP 2333-156-8.
     The F2 populations of RP 2333-156-8 with parents possessing known gene for resistance to gall midge, e.g. Gm 1 (Samridhi, Ruchi and Asha), Gm 2 (Phalguna), Gm 4 (Abhaya) and Gm 5 (ARC 5984) segregated into 15R:1S ratio, indicating the non-allelic nature of the gene of RP 2333-156-8 with Gm 1, Gm 2, Gm 4 and Gm 5. The F2 populations of RP 2333-156-8 with RP2068- 18-3-5, having gm3, the recessive gene for gall midge resistance segregated into 13R:3S ratio, indicating the non-allelic nature of the gene of RP 2333-156-8 with gm 3 (Table 2). The F3 population of this cross segregated into 7R:8Sg:1S ratio confirming the non-allelic nature of the gene of RP 2333-156-8 with Gm 1, Gm 2, gm 3, Gm 4 and Gm 5. Rice variety Duokang 1, from China having Gm 6 is susceptible to gall midge biotype 1 of India. The gene for resistance of RP 2333-156-8 is therefore different from Gm 6. We have therefore designated this gene as Gm 7.