| Budget Amount *help |
¥2,960,000 (Direct Cost: ¥2,600,000、Indirect Cost: ¥360,000)
Fiscal Year 2007: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2006: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Research Abstract |
Optimum marker-based procedures for producing high-degree gene pyramided lines via assembling genes from multiple donor lines were discussed. The procedures proceed in two steps ; a plant that has all objective genes in a heterozygous state (root genotype) is produced in the first step, and in the second step, a plant that has all the genes in a homozygous state is selected in the progeny of the root genotype. When pyramiding genes onto the genome of a particular recipient line, backcross should be performed separately for each donor prior to the crossing between the donors. To produce the root genotype, plants obtained through the backcross should be crossed in a schedule with structure and disposition of the plants as symmetric as possible. Ideal-type schedules in the presence of four to eight donors are presented. In the absence of any particular recipient genome (no need of the backcross), the donors themselves should be crossed in a schedule with completely tandem structure in which donors with fewer target markers enter the schedule in earlier stages. For selection in the second step, a strategy with combined use of haplo-diploidization and crossing between selected plants will be highly efficient ; selection starts with haplo-diploidized plants raised from the root genotype, and in the absence of a plant with the objective marker genotype, two plants with the best complementary genotypes are crossed to produce a hybrid, which in turn is haplo-diploidized for the next round of selection. In this strategy, even a plant having as many as 20 target markers, can be obtained at an almost perfect certainty in about three rounds of selection with a maximum of 200 tested plants per round.
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