| Research Abstract |
Objective of this research is to carry out a survey on the dominant/recessive relationships of S-alleles in the self-incompatibility of Brassicaceae and to investigate the mechanism of the dominant/recessive relationships.
Out of 300 possible combinations between 25 S-allele homozygotes of Brassica campestris, 275 F_1s were raised and their dominant/recessive relationships were surveyed in the two cases, ie heterozygotes in stigma or anther, separately. In the case of stigma heterozygotes, the S-alleles were classified into two groups ; codominant and dominant groups. In the case of anther heterozygotes, they were classified into three groups ; codominat, dominant and recessive groups. The dominant/recessive relationships of S-alleles were indepent between stigma and pollen. There were 14 combinations where the heterozygotes were compatible to both parental strains, whereas they were self-incompatible. These S-alleles are considered to be independent weakening genes.
Several SLG,SRK genes were isolated from cDNA or genomic DNA libraries. In S9-homozygotes, the sequences through the promoter region and S-domain across about 1.7kb were completely identical between SLG and SRK.This identity should be concerned with the dominance relationship at the stigma side. In S29 homozygotes, SLG and SRB clones were isolated, and it was revealed that they are highly homologous to each other. Because of short period of this project research, we could not obtain whole the SLG and SRKs. However it is expected that the objective of this study will be attained in near future by the development of this line of study.
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