Table 1  Genotype frequencies of a marker locus linked to S24 in backcross populations derived from indica/japonica crosses
Parental genotype at the EFS locusbNo. of plants with each genotypec
Populationajp/jpin/jpin/inTotal% of jp/jpdχ2 for 1:2:1
AI-NIL-F2efs-j/efs-j669671424.252.52***
IA-NIL-F2EFS-i/EFS-i2321256933.310.68**
BC2F2-1EFS-i/efs-j24686115315.719.78***
BC3F2-8-4EFS-i/efs-j18483510117.85.97 NS
BC4F2-8-4-1EFS-i/efs-j41895918921.74.07 NS
BC3F2-8-6eefs-j/efs-j765501225.730.83***
  • NS, not significant; **P < 0.01, ***P < 0.001.

  • a AI-NIL represents Asominori carrying the IR24 allele for S24, and IA-NIL represents IR24 carrying the Asominori allele for S24. See Figure 1. The BC2–4 populations were derived from a cross between Nipponbare and 93-11.

  • b All parents were heterozygous for S24 (S24-i/S24-j). The parental genotypes at the EFS locus were determined on the basis of the marker locus mE4. Those that were homozygous for the EFS locus are shown in boldface type. EFS-i and efs-j denote indica and japonica alleles for the EFS locus, respectively.

  • c DNA marker mS2 linked to S24 was used for genotyping, with the exception of the BC2F2 population, for which mS3 was used. jp/jp, japonica homozygous; in/jp, heterozygous; in/in, indica homozygous.

  • d The expected proportion (%) of the jp/jp genotype in each population is 25%. Note that a reduced proportion of the jp/jp genotype at mS2 (linked to S24) (underlined) was observed in populations that were homozygous for the japonica EFS allele (efs-j/efs-j).

  • e BC3F2-8-6, a sister line of BC3F2-8-4, was homozygous for the japonica EFS allele.