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- Author or Editor: Ryutaro Tao x
Leaf extracts of 163 Japanese persimmon cultivars (Diospyros kaki L.) and six other Diospyros species were analyzed for isozyme variation of glucose phosphate isomerase (GPI, E C 188.8.131.52) and malate dehydrogenase (MDH, E C 184.108.40.206). With both systems, the bands were sharp and well-resolved, and intracultivar polymorphism was absent. Isozyme phenotypes were more varied with GPI than with MDH. With Japanese persimmons, GPI yielded 24 different banding patterns, and six cultivars were uniquely discriminated by this enzyme alone. MDH produced only three different banding patterns, with none of the cultivars discriminated. When both enzyme systems were taken together, 18 cultivars were uniquely discriminated and the rest could be classified into 22 groups of 2 to 18 cultivars each.
Callus cultures were initiated in the dark from leaf primordia, stem internodes, and young leaves of adult Japanese persimmon (Diospyros kaki L.) to induce adventitious buds. A high frequency of regeneration occurred on Murashige and Skoog medium (MS) with half the normal NH4NO3 and KNO3 concentration (1/2N) and containing 10 μm zeatin or 1 μm 4PU-30 in combination with 0.1 μm IAA, or MS(1/2N) medium containing 0.03 to 0.1 μ m IAA or 0.01 to 0.03 μm NAA combined with 10 μm zeatin. No significant differences in the capacity of regeneration were observed among the calli from different explant sources. Only eight of 16 cultivars formed adventitious buds on MS(1/2N) medium containing 10 μm zeatin and 0.1 μm IAA, with the percentage of explants forming adventitious buds ranging from 2% to 72%. Chemical names used: indole3-acetic acid (IAA); 1-naphthaleneacetic acid (NAA); N-phenyl-N'-(2-chloro-4-pyridyl)urea (4PU-30).
Interspecific hybrids between Diospyros glandulosa (2n = 2x = 30) and D. kaki cv. Jiro (2n = 6x = 90) were produced by electrofusion of protoplasts. Protoplasts were isolated from calli derived from leaf primordia, fused electrically, and cultured by agarose-bead culture using modified KM8p medium. Relative nuclear DNA contents of calli derived from fusion-treated protoplasts were determined by flow cytometry. One-hundred-forty-nine of 166 calli obtained had the nuclear DNA content of the sum of those of D. glandulosa and D. kaki cv. Jiro. RAPD analysis showed that the 149 callus lines yielded specific bands for both D. glandulosa and D. kaki cv. Jiro and they appeared to be interspecific somatic hybrid calli. Shoots were regenerated from 63 of the 149 interspecific hybrid calli. PCR-RFLP of chloroplast DNA analysis, flow cytometric determination of nuclear DNA content, and RAPD analysis revealed that the 63 interspecific hybrid shoot lines contained nuclear genome from both the parents but only chloroplast genome from D. glandulosa. Microscopic observation of root tip cells confirmed that somatic chromosome numbers of the interspecific hybrids were 2n = 8x = 120.
A potentially dwarfing rootstock for japanese persimmon (Diospyros kaki L.) was propagated by single-node stem cuttings taken from root suckers. When a mature tree was cut down at ground level and part of the roots was exposed to the air, numerous suckers formed on the exposed parts of the roots. Single-node stem cuttings 3 to 4 cm (1.2 to 1.6 inches) long survived and rooted better than 10-cm (3.9-inch) and 25-cm (9.8-inch) leafy stem cuttings with several buds. Dipping cuttings in 3000 mg·L-1 (ppm) IBA for 5 s or in 25 mg·L-1 IBA for 24 h resulted in similar rooting. Most of the single-node stem cuttings taken in late-June and July survived and rooted well, whereas those prepared in late August rooted poorly and few survived. The survival and rooting percentages were unaffected by the position on the suckers (top vs. base) from which cuttings were taken. High relativehumidity in the propagation frame appeared to enhance survival and rooting. This clonal propagation method will make a rapid multiplication of japanese persimmon, a difficult-to-root species, possible. Chemical name used: indole-3-butyric acid (IBA).
Growth of micropropagated Japanese persimmon trees (Diospyros kaki L. cv. Nishimurawase) during the initial 3 years after field establishment was compared with that of grafted trees on seedling stocks. Judging from the mean length of annual shoots per tree and the yearly increases in height, trunk diameter, and top and root dry mass, the grafted trees on seedling stocks grew poorly during the first and second growing seasons, while micropropagated trees, raised in an outdoor nursery, developed poorly only during the first growing season. In contrast, micropropagated trees raised in pots fared well soon after field establishment. These trees had more fine than middle and large roots; in contrast, grafted trees on seedling stocks had one large taproot, which died back to some extent after field establishment, with few fine roots.
Japanese pear (Pyrus pyrifolia) and quince (Cydonia oblonga), both classified in the subfamily Maloideae, show differences in inflorescence architectures despite of the fact that they are genetically closely related. We previously isolated flowering related genes, LEAFY (LFY) and TERMINAL FLOWER 1 (TFL1) homologues, from these species and showed that they had two types of homologues for each gene. In this study, we examined the expression pattern of LFY and TFL1 homologues in these species by in situ hybridization and RT-PCR. The floral bud was dissected to small pieces under stereomicroscope; apical meristem, scales/bracts, pith, floral meristem, and inflorescence; and then used for RT-PCR. The LFY homologues were expressed in apical meristem and scales/bracts before the floral differentiation in both Japanese pear and quince. After floral differentiation, the expression was observed in floral meristem, scales/bracts and pith in both the species. The TFL1 homologues were strongly expressed in the apical meristem, but their expression was drastically decreased just before floral differentiation. It is considered that the decrease of expression of TFL1 homologues is a sign of floral initiation. The expression of TFL1 homologues was transiently increased at the beginning of floral differentiation in both species. Moreover, one of TFL1 homologues in Japanese pear was continuously expressed in the inflorescence part in the floral primordia, whereas expression of TFL1 homologues in quince almost completely disappeared after a solitary floral meristem was initiated. It was suggested that TFL1 homologues may also be involved in the inflorescence development of Japanese pear.
Dormant bud explants taken from mature trees of Japanese persimmon cv. Hiratanenashi were established successfully on modified Murashige and Skoog's medium with nitrate reduced to half-strength [MS (½NO3)] or woody plant medium, both supplemented with 22.2 μM (5 mg°liter−1) BA. Shoot proliferation in subcultures also was best at 22.2 μM (5 mg°liter−1) BA in MS (½NO3) medium, but growth was of the rosette type. Shoot elongation, however, was stimulated the most in the same medium supplemented with 24.6 μM (5 mg°liter−1) 2iP instead of BA. Rooting of the proliferated shoots was enhanced by the treatment with IBA at 1.23 mM (250 mg°liter−1). Chemical names used: N-(phenylmethyl)-1H-purin-6-amine (BA), N-(3-methyl-2-butenyl)-1H-purin-6-amine (2iP), 1H-indole-3-butanoic acid (IBA).
Primordial leaves of Japanese persimmon (Diospyros kaki L. cv. Jiro) were excised from dormant buds and cultured on Murashige and Skoog medium with the nitrates reduced to half strength (MS½N) and supplemented with 0.1 to 10.0 µm zeatin + 0.1 to 10.0 µm IAA. After 40 days of culture in the dark, yellowish-white calli were formed at 10.0 µm zeatin + 1.0 µm IAA. When these calli were transferred to MS½N medium supplmented with zeatin (1.0 to 10.0 µm) + IAA (0 to 10.0 µm), 24% of them produced adventitious buds at 10.0 µm zeatin + 0.1 µm IAA under a 12-hr photoperiod. Further shoot growth occurred on the same medium without IAA. Basal ends of the shoots were quick-dipped in 1.25 mm IBA and placed on half-strength MS½ N medium. Nearly two-thirds of the dipped shoots rooted within 30 days. Plantlets regenerated in vitro were then transferred to a mixture of 1 peat: 1 perlite: 1 vermiculite and acclimatized for potting. Chemical names used: 1H-indole-3-acetic acid (IAA); 1H-indole-3-butyric acid (IBA); (E)-2-methyl-4-(1-H-purin-6-ylamino)-2-buten-1-o1 (zeatin).
Self-compatible cultivars of Japanese apricot (Prunus mume Sieb. et Zucc.) have a horticultural advantage over self-incompatible ones because no pollinizer is required. Self-incompatibility is gametophytic, as in other Prunus species. We searched for molecular markers to identify self-compatible cultivars based on the information about S-ribonucleases (S-RNases) of other Prunus species. Total DNA isolated from five self-incompatible and six self-compatible cultivars were PCR-amplified by oligonucleotide primers designed from conserved regions of Prunus S-RNases. Self-compatible cultivars exhibited a common band of ≈1.5 kbp. Self-compatible cultivars also showed a common band of ≈12.1 kbp when genomic DNA digested with HindIII was probed with the cDNA encoding S 2-RNase of sweet cherry (Prunus avium L.). These results suggest that self-compatible cultivars of Japanese apricot have a common S-RNase allele that can be used as a molecular marker for self-compatibility.