|Budget Amount *help
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1987: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1986: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1985: ¥1,000,000 (Direct Cost: ¥1,000,000)
To construct gene scheme of the basic vegetative period of rice, 19 isogenic lines of Taichung 65 having an earliness gene were established. Gene analysis of heading time was carried out, using above 19 isogenic early-heading lines. The experimental results showed that respective lines had an dominant earliness gene. An allelism test of earliness gene showed that 18 lines had an earliness alleles on the same locus, Ef_1 which was determined by Tsai (1976), and that 1 line had other gene, Ef_x. However, segregation data of heading time of hybrids involving the isogenic early-heading line carrying Ef_x was not coincided with other linkage data.
To know the chromosame carrying the Ef_1 gene, linkage analysis was studied out, using isogenic translocation lines of Taichung 65, and an linkage tester having the same genetic background of that of Taichung 65. The experimental results showed that the gene locates on the seventh chromsome, although Tsai (1973) reported that Ef_1 was linked with t
he lazy growth habit gene, la locating on the ninth chromosome, Then, it was concluded that linkage relation between 2 genes, Ef_1, and la was spurious, as the recombination value of 38% was considerably large.
To determine other earliness genes, 19 extremely eary-heading families were bred by more than 7 times of successive backcrossigs to a native variety in Hokkaido, kokusyokuto-2 or A58 with an isogenic early-heading line, T65・ER-1 having Ef_1. 2 other earliness genes were newly determined from allelism test between them.
Varieties having long anthers are generally tolerant to cold at reproductive satage (Suzuki 1982). All isogenic early-heading lines having Ef_1 produced short anthers, compared with those of Taichung 65. Then, a linkage relation between tnem was studied to know whether Ef_1 affects pleiotropically the anther length, or genes controling two traits are closely linkedwith each other. The short anther character was estimated to be incompletely dominat. Although, none of recombinats were observed in F_2 plants of T65・ER-1/T65, four plants showing early heading and long anthers were observed in 973 B_1F_1plants, T65・ER-1/T65//T65. This suggests that two traits are controled by different genes to be linked closely. Then, more precise progeny test should be carried out to know whether they were recombinants or not. Less