Plant Genome IV Conference Plant Genome IV Conference
Molecular markers are extensively applied to our hybrid rice breeding. A defective atp6 gene conferring BT type cytoplasmic male sterility (CMS) was known to be located on the mitochondrial genome. Sequences of both sides of this gene were used for PCR primers for detecting CMS as a co-dominant marker. During development of new CMS lines which were made from protoplasts fusion, existence of BT type mitochondria were effectively analyzed with this PCR system. Persistence of this mitochondria in CMS lines was also monitored with this PCR system. Restorer(R) line is another element of hybrid rice seeds production. Rf-1 gene which confer restoration of fertility to BT type CMS plants was required for R-line. Isogenic lines of w/o Rf-1 gene with background of Taichung 65 were constructed by Prof. Shinjo of Ryukyu University. Using these isogenic lines and after 800 kinds RAPD assays, we identified 1 primer linking closely to Rf-1 gene. After sequencing of this RAPD amplicon, the RAPD primer was converted to normal PCR primer set. With this primers, R-lines were effectively bred using PCR. PCR diagnostics detecting wide compatibility gene and a gene concerning taste were also conducted during hybrid rice breeding. The other breeding projects using molecular markers in Japan also will be reviewed.