| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1991: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1990: ¥1,800,000 (Direct Cost: ¥1,800,000)
|
|---|
| Research Abstract |
Genetical, morphological and histological studies were carried out to demonstrate the characteristics of various types of dwarf seedlings occurred in Citrus and Poncirus. When the polyembryonic cultivars were used as a pistilate parent, zygotic seedlings were determined by isozyme analysis. In the seedlings from self-pollination of 'Flying Dragon', normal and Flying Dragon-shaped seedlings and very dwarf seedlings segregated at the ratio 3:1, indicationg that 'Flying Dragon' is heterozygous for single recessive dwarf gene and that very dwarf seedlings are homozygous for it. This assumption were supported by the evidence that in crosses between citrus cultivars and 'Flying Dragon', normal seedlings were produced.
Since the growth of the very dwarf seedlings was promoted by 5-25ppm gibberellin treatment and grafting on normal trifoliate orange, this reseccive dwarf gene is considered to inhibit gibberellin synthesis. The morphological and histological charactors of very dwarf seedlings we
… More
re very different from those of normal and Flying- Dragon-shaped seedlings.
The elongated dwarf seedlings on normal trifoliate orange could be divided into normal and Flying Dragon-shaped types, indicating that Flying Dragon dwarfness was controlled by Flying Dragon dwarf gene. However, we could not clearly resolved the mechanisum of the ingeitance.
Since selfed 'Chimotto' produced normal and dwarf seedlings at the ratio 1:3 and since citrus and Poncirus cultivars pollinated with 'Chimotto' produced them at the ratio 1:1 and 15:1, 'Chimotto' type dwarfness is considered to be controlled by dominant major gene which interacts with modified genes. 'Bouquet' type dwarfness is thought to be controlled by single dominant gene which interacts with lethal gene, since seedlings obtained from citrus cultivars pollinated with 'Bouquet' could be divided into dwarf and normal types at the ratio 2:1. Further study for these hypothesis is now in progress.
Lastly, the present results suggest that use of 'Flying Dragon' as a pistilate parent is sutable for breeding dwarf rootstocks for citrus, since 10% of zygotic seedlings from self-pollination of 'Flying Dragon' showed precocious flowering. Less
|
