Gamete abortion locus detected by segregation distortion of isozyme locus Pgi1 in indica-japonica hybrids of rice (Oryza sativa L.)

Abstract

In an attempt to stabilize the pollen fertility of indica-japonica hybrids of rice by the incorporation of segregation-distortion-neutral alleles, a locus causing distorted segregation of male gamete in indica-japonica hybrids was identified with an isozyme marker gene Pgi1 on chromosome 3. In seven F2 populations of indica-japonica crosses and 25 F3 lines from IR 36/Kamairazu, the japonica-type allele Pgi1-2 was transmitted via male gamete with a ratio of 0.29 to 0.38 instead of the normal one of 0.5 due to the presence of a gametophyte gene ga14. The recombination value between the locus ga14 and the marker gene Pgi1 was estimated to be 0.29 by using 57 F3 lines of IR 36/Kamairazu. The male gamete transmission rate (k) of ga14-j was estimated to be 0.13∼0.22 against the ga14-i instead of the normal one of 0.5 based on the data from the F2 and F3 lines. The locus ga14 which reduced the frequency of male gametes harboring ga14-j in some indica-japonica hybrids was located in the order of Pgi1∼ga14∼bc1 on chromosome 3.