TRISOMIC ANALYSIS OF A STRONG PHOTOPERIOD-SENSITIVITY GENE-E1 IN RICE(ORYZA-SATIVA L)

Recent genetic analyses on heading-time of rice indicated that almost all the well adapted varieties in the temperate zone carry a strong ph otoperiod-sensitivity gene E1, a dominant allele of E1 locus. In order to identify the chromosome on which E1 is located, a trisomic analysi s was made using two primary trisomic series originating from the japo nica varieties, Nipponbare and Kinmaze, respectively. The Nipponbare a nd Kinmaze series were crossed with heading-time tester lines, EG0 and EG3, respectively, both of which did not carry the E1. The F2 populat ions for chromosome 1, 2, and 3 could not be analyzed due to lack of s eed. All the other F2 populations showed distinct segregation into ear ly-type and late-type plants caused by the E1 locus segregation, which suggested that the trisomic analysis for E1 locus could be efficientl y made. Both disomic and trisomic groups in the F2 population from the cross of the trisomic line for chromosome 7 x EG0 showed a segregatio n ratio significantly different at the 1% level from a ratio of 1 [e1e 1; early]: 3 [E1e1, E1E1; late]. This suggested that E1 was located on chromosome 7. Subsequently, the Linkage analysis was made using three morphological marker genes on chromosome 7. It was recognized that E1 was linked to rfs (rolled fine strip gene) and slg (slender glume gen e) with recombination values of 16.3 +/- 5.88 and 9.1 +/- 4.72%, respe ctively. From these results, it can be concluded that E1 is most likel y to be located on chromosome 7.