Jhitpiti, a traditional gall midge resistant accession from Rice Germplasm of lndira Gandhi Agricultural University, Raipur, Madhya Pradesh, India was investigated for the resistance. Jhitpiti was crossed with susceptible parents (Kranti and TN1) and with parents possessing known genes for resistance during wet season of 1999. Half of the F₁ seeds were grown in dry season of 2000 to produce F₂ seeds. F₂ populations along with F₁'s and parents were field screened during wet season of 2000.

The test populations were flanked on both sides with purple colored highly susceptible line R 2270 and artificial light during night was provided as additional measure to attract the insects. Observations were recorded when susceptible parents developed 100 percent infestation on per plant basis. Presence of single silver shoot was taken as an index of susceptibility.

The natural infestation of gall midge in wet season of 2000 was very high. Hundred percent infestation was observed on all the plants of susceptible check and no damage was observed in the resistant cultivars (Table 1). The F₁ plants of Jhitpiti with susceptible parents Kranti and TN1 showed resistant reaction and the F₂ populations segregated in a ratio of 3R:1S, indicating that a single dominant gene governs resistance in Jhitpiti (Table 1).

The F₂ populations from crosses of Jhitpiti with parents possessing known dominant genes for resistance; Gm1 (Samridhi), Gm2 (Phalguna) ( Chaudhary et al. 1986) and Gm4 (Abhaya) (Shrivastava et al. 1993), Gm5 (ARC 5984) (Kumar et al. 1998), Gm7 (RP2333-156-8) (Kumar et al. 1999) segregated into 15R:1S ratio in F₂. The F₂ population from the cross of Jhitpiti with the RP2068-18-3-5, the donor for the recessive resistant gene, gm3 (Kumar et al. 1998) segregated in 13R:3S ratio in F₂ (Table 2). Gene Gm6 for gall midge resistance gene identified in rice variety Duokang 1 from China (Yang et al. 1997) is susceptible to gall midge biotype 1 of India. This clearly indicated that the gene for gall midge resistance Jhitpiti is non-allelic to Gm1, Gm2 gm3 , Gm4, Gm5, Gm6, and Gm7. Therefore, this gene is designated as Gm8(t).

Acknowledgement

This study is a part of Rockefeller Foundation supported project "Identification of new gene(s) for gall midge resistance" to Indira Gandhi Agricultural University, Raipur, Madhya Pradesh, INDIA.

References

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