Senescence of carnation flowers is characterized by autocatalytic ethylene production from petals and subsequent wilting of the petals. Recent studies on the regulation of ethylene production and wilting in senescing carnation petals revealed that (1) petal senescence is triggered by ethylene evolved from the gynoecium during natural senescence, (2) ethylene production in the gynoecium is induced by a factor(s) other than pollination signals in carnation flowers lacking anthers, (3) there are two subsets of ethylene responses in the petals, one responsible for autocatalytic ethylene production and the other for wilting, (4) expression of genes involved in the execution of petal withering is differently regulated between ethylene-dependent or -independent senescence. Furthermore, it was revealed that the generation of transgenic carnation without detectable ethylene production is useful to prolong the vase life of cut carnation flowers.

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To obtain genetic information on carotenoid content in Citrus fruit for a breeding program, we investigated quantitative trait loci (QTL) in a mapping population derived from a cross between ‘Okitsu-46’ and ‘Nou-5’. Among individual progeny, total and each carotenoid contents were segregated in a transgressive manner. QTLs for total and each carotenoid contents were detected by Kruskal-Wallis analysis (P < 0.01) and interval mapping (LOD (logarithm (base 10) of odds) > 2.0) from 51 individuals. Most of the QTLs for each carotenoid component were mapped to different locations on the linkage map. In β-cryptoxanthin, the strongest QTL (LOD 3.4) was detected on linkage group 6 of ‘Nou-5’, and accounted for 26.9% of explainable variance. LOD scores of QTLs for total carotenoid content were lower than those for each carotenoid content. There were one QTL for total carotenoid content at the criteria of LOD > 2.0, and seven weaker QTLs, which overlapped with QTLs for each carotenoid component. The effects of QTLs detected for each carotenoid content worked cumulatively to increase total carotenoid content. This study provides preliminary data because we obtained data in only one season and from a limited number of individuals (n = 51). However, the results suggested that QTL information could be used to generate DNA markers to select progeny with higher carotenoid content.

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In fruit trees and vegetative reproductive plants, viral elimination from mother plants is conducted to produce virus- and viroid-free nursery plants. In citrus, shoot tip culture and semi-micrografting combined with thermotherapy were adopted for viral elimination; however, these methods should be modified for ease or higher efficiency. One solution might be the application of effective antiviral agents. In this study, we tested the efficacy of 4 antiviral agents, ribavirin, foscarnet, zidovudine, and enfuvirtide, against Satsuma dwarf virus (SDV) in Citrus unshiu Marc. ‘Ueno-wase’ to screen effective agents. The results showed that foscarnet had the highest efficacy against SDV at semi-micrografting combined with thermotherapy, and that the efficacy was significantly different from that of the untreated control. On the other hand, ribavirin, which was thought to be efficient against some citrus viruses, has no significant effect against SDV. There were no harmful effects of foscarnet or ribavirin on re-generation. It was considered that the optimization of treatment method and concentration is required before applying ribavirin as an antiviral agent against SDV. Foscarnet was thought to be highly effective against SDV and was also expected to have high efficacy against other plant viruses. Moreover, our results suggested the possibility that other human antiviral agents that have not been investigated in plants could be effective against plant viruses.

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Persimmon cultivars are classified into four types depending on the nature of astringency loss of the fruit, namely pollination constant non-astringent (PCNA), pollination variant non-astringent (PVNA), pollination variant astringent (PVA), and pollination constant astringent (PCA). Among these four types, PCNA is the most important cultivar for persimmon breeding due to the stable loss of natural astringency on the tree. The trait of natural astringency loss is recessive in Japanese PCNA cultivars, while that in the Chinese PCNA cultivar, ‘Luo tian tian shi’, is dominant and the latter locus, termed CPCNA, is different from that in Japanese cultivars. In order to develop a molecular marker for the selection of the CPCNA-type cultivar, we performed amplified fragment length polymorphism (AFLP) in combination with bulked segregant analysis for F₁ offspring derived from ‘Luo tian tian shi’, which was used as the maternal parent. A total of 384 primer combinations were tested, and three AFLP markers, namely EACT-MCCC-222 (RO1), EGGC-MCTC-309 (RO2), and EGCC-MCGA-105 (RO3), linked to the CPCNA dominant allele were obtained. Among these markers, EGGC/MCTC-309 (RO2) was converted into a sequence-characterized amplified region (SCAR) marker. PCR analysis using F₁ offspring (n = 264) revealed that the relevance ratio of the SCAR marker was 94%. The polymorphism of the RO2 marker, which was strongly linked to the CPCNA dominant allele, was detected in only two Chinese PCNA cultivars, namely ‘Luo tian tian shi’ and ‘Tian bao gai’, among the Chinese, Korean, and Japanese cultivars tested. These results indicate that the RO2 marker contributes to marker-assisted selection for breeding programs of new PCNA cultivars having the CPCNA trait.

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To improve the fruit and seed productivity in hermaphrodite ‘Sunrise Solo’ and female ‘Wonder Flare’, we investigated seasonal variations in the frequency of sexually altered abnormal misshapen flowers (carpelloid and pentandoria flowers) and female sterile flowers, fruit and seed yield, pollen germination ability, and the reproductive function of pistils under greenhouse cultivation conditions in Okinawa, Japan. In ‘Sunrise Solo’, the percentages of abnormal misshapen flowers were 42–66% from July to October (average temperature: 25.6–30.5°C), though they were below 10% from February to March (14.6–16.8°C) and December to January (16.9–18.1°C). The percentages of female sterile flowers were low (below 10%) from March to November (16.8–30.5°C), but high (13–37%) from December to February (14.6–18.1°C). Seed and fruit yield increased in May (24.6°C) and November (19.4°C), but decreased from January to March (14.6–18.1°C) and July to September (28.2–30.5°C). Pollen germination rates (52–87%) were high from April to June (22.2–27.2°C) and October to November (19.4–25.6°C) and pollen tube length was long (208–272 μm) during the same periods, while the rates were low (5–32%) and the tube length was short (63–134 μm) from January to March (14.6–18.1°C); moreover, no germinated pollen was found from July to September (28.2–30.5°C). These results of the seasonal fluctuation in pollen germination ability were supported by pollen germination tests performed in an incubation chamber, i.e., pollen germination rates were high (72–80%) between 20 and 25°C, but low (0–56%) below 15°C and above 30°C; however, the pistils of ‘Sunrise Solo’ and ‘Wonder Flare’ retained their reproductive function even during the period of low (16.7°C) and high (29.5–30.5°C) temperatures, i.e., fruit and seed yields were improved by pollination using pollen (germination rate: about 35%) collected from plants cultivated in an open field during the high temperature period or pollen preserved at sub-zero temperatures during the low and high temperature periods. These results indicate that fruit and seed production in papaya under low or high temperature conditions is unfavorable for pollen germination, but could be improved by artificial pollination with preserved pollen.

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Morphological and anatomical changes in roots associated with their development were investigated in grapevines. When new roots initiated from the suberized structural root in grapevines, the tip of the root expanded outward and the suberized outer layer was detached from the surface of the root tip. At the onset of root initiation, the cell nucleus reappeared in the apical meristem, and cell division occurred. Once approximately five xylem vessels per pole had appeared, the Casparian strip appeared as a dot in the center of the radial wall of the endodermis. At a point 150 mm from the root tip, the endodermis was completely suberized and the number of xylem vessels per pole increased. In younger roots, suberization of the exodermis was observed earlier than in the endodermis, although the Casparian strip could not clearly be detected in the exodermis. As the root aged, a gap formed between the endodermis and pericycle. Before the endodermis was sloughed off from pericycle layers, cell division was observed in the pericycle and the suberized pericycle layers increased.

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An aseptic bioassay utilizing female and male donor materials was performed in order to assess the allelopathic activities of cladophylls and root systems in dioecious asparagus. The aseptic sandwich method revealed that the growth of acceptor plants was significantly inhibited by the addition of over 30 mg fresh weight of cladophylls. When female and male cladophylls were separately adopted for the sandwich method, there was no sexual difference in the allelopathic activity of both youthful and senescent cladophylls. To detect the allelopathic effects of root systems, the plant box method employing female and male regenerants was used aseptically, and the growth of acceptor plants was seriously inhibited irrespective of sex expression in donor plants. Early in vitro flowering seedlings expressing individual sex were effectively used for the bioassay, and the results indicated that the degree of allelopathic activities was the same as that in regenerants. These results show that allelopathic activity in female and male plants was equivalent, and that the application of materials that can distinguish between the sexes would be useful for assaying the mutual effects of sexuality on allelopathy. The aseptic bioassay system that employed female and male materials presented here could promote the isolation and identification of allelochemicals.

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Most modern carnation (Dianthus caryophyllus L.) cultivars tend to have little fragrance. Wild Dianthus species having a strong or characteristic fragrance were thought to be promising genomes for the introduction of fragrance into these modern carnation cultivars. We selected 10 plants with fragrant flowers and 1 hardly fragrant plant, which was used as a negative fragrant control, from wild Dianthus gene resources of National Institute of Floriculture Science, and divided them into 4 groups according to their sensory characteristics. Gas chromatography-mass spectrometry (GC-MS) analysis indicated that the scent compounds of wild Dianthus species were principally composed of 18 volatile compounds, which were benzenoids, terpenoids, or fatty acid derivatives. The sweet and medicinal fragrance of Group 1, having the strongest scent, was due to methyl salicylate, a benzenoid. The citrus-like fragrance of Group 2 was due to β-ocimene and β-caryophyllene, two terpenoids. The green leafy odor of Group 3 was due to (Z)-3-hexenyl acetate, a fatty acid derivative. In Group 4 flower, which had little fragrance, scent compounds were hardly detected. In theses flowers, the composition of the emitted scent compounds differed from that of the endogenous scent compounds; the scent compounds, having a high vapor pressure and a relatively low boiling point, were efficiently emitted from the flower organs. Major benzenoids in D. hungaricus of Group 1 were distributed in petal limbs, and major terpenoids in D. superbus of Group 2 and major fatty acid derivatives in D. sp. 2 of Group 3 were distributed in petal bottoms and collectively, in the stamens and pistil. These results demonstrate that the floral tissues which produce fragrance differ for each Dianthus species. In this study, Group 1, being rich in methyl salicylate, and Group 2, being rich in β-ocimene and β-caryophyllene, were suggested important gene resources for introducing fragrance into carnations because these scent compounds have a pleasant smell and contribute strongly to the fragrance features of their respective flowers.

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Carnation stunting and shoot proliferation (CSP) syndrome typically shows symptoms of shoot shrinking and proliferation. Thus, it is believed that biosynthetic or metabolic problems of endogenous phytohormones are related to the developmental process. On the other hand, it is known that the rhizosphere environment greatly influences the incidence of this syndrome, although little abnormality is observed in the roots. In this syndrome, grafting tests were performed using a susceptible and non-susceptible cultivar to determine the relationship between the underground and aerial parts of the plant. The grafted plant showed symptoms when the stock was a susceptible cultivar, even if the scion was a non-susceptible cultivar. These findings confirm that the roots make an important contribution to the appearance of symptoms, and that typical symptoms of stunting and shoot proliferation appear in the aerial parts due to some signals from underground parts. These signaling substances may only occur in the roots, and may change before the stunting symptom appears as the first stage of the syndrome. Thus, the concentrations of endogenous phytohormones were quantified, as possible signaling substances. However, the concentrations of phytohormones measured in this test did not change in the roots, and it seems very likely that these phytohormones are not the signals. In contrast, in the shoot apices, indole acetic acid (IAA) concentration decreased at the same time as the stunting symptoms started to appear in the expanding leaves. The ratio of cytokinins (CKs) to IAA concentration increased because IAA concentration decreased and the concentration of CKs did not. It is clear from these findings that the appearance of symptoms in the shoots is influenced by a biosynthetic abnormality of IAA and a corresponding imbalance of CKs and IAA.

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Oriental hybrid lily flowers have a pleasant fragrance. Especially in a confined space, however, the scent can be perceived as too strong and therefore unpleasant. Our analysis of the major scent compounds in cut flowers of ‘Casa Blanca’ lilies, which is one of the most popular oriental hybrid lilies in Japan, identified two aromatics (benzyl alcohol and iso-eugenol) and two terpenoids (linalool and cis-ocimene). In addition, p-creosol (aromatics) was detected as a minor component. Based on sensual impressions, we assumed that iso-eugenol and p-creosol were the main causes of the unpleasant odor. We concluded that inhibitors of the biosynthesis of aromatics could decrease concentrations of these compounds and make the fragrance of ‘Casa Blanca’ less unpleasant. The biosynthesis of aromatics is generally catalyzed by phenylalanine ammonia-lyase (PAL). We used aminooxy acetic acid (AOA) and L-2-aminooxy-3-phenylpropionoic acid (AOPP) as PAL inhibitors. Application of AOA and AOPP at 0.1 mM and 1.0 mM by vase treatment decreased the emissions of scent compounds. For practical application, AOA was selected because of its much lower cost. Continuous treatment with AOA decreased the emissions of scent compounds to 10 to 20% of the control at a constant ratio at all times of day on the second and third days after flowering when ‘Casa Blanca’ emitted the greatest amounts of scent compounds. Similar effects were found on the last day of flowering. Under certain conditions, temporary treatment for 24 h evoked similar effects as continuous treatment. Application of 1.0 mM AOA caused chemical injury to the tepals, but 0.1 mM AOA did not. Treatment of plants with opened flowers was less effective than treatment at a late bud stage. In summary, continuous post-harvest treatment with 0.1 mM AOA of ‘Casa Blanca’ at late flower bud stages can decrease the emissions of scent compounds and render the fragrance milder without affecting flower morphology through its period of use as an ornamental.

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The shapes of the petal curvature and two-dimensional (2D) petal shape of Eustoma flowers were quantitatively evaluated by Fourier transform analysis. Petal curvature was traced along the abaxial surface of petal midribs observed in the lateral view. The curved lines were transformed to Fourier coefficients and then subjected to principal component analysis. Petal curvature could be described using the first three principal components (PC), which accounted for 95% variation of overall PCs. The first and second PC described the opening angle of the flower and inward curvature of the middle the part of the petals, respectively. Petal shape could be described using the first two PCs, representing petal width and the position of the weighted center, respectively. A total of 122 cultivars and breeding lines were clustered based on Self-Organization Maps (SOMs) using the Fourier coefficients of petal curvature and petal shape. The SOM characterized four typical corolla shapes; 1) bowl-shaped, 2) tall-cup-shaped, 3) trumpet-shaped, and 4) funnel-shaped corolla. The second PC of petal curvature showed a high correlation with the first PC of the 2D petal shape, indicating that the formation of petal curvature observed in bowl- and tall-cup-shaped corollas is associated with the wide shape of the petals.

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Fourteen anthocyanins were detected in the flowers of R. simsii distributed in Vietnam and Japan. The anthocyanin constituents of R. simsii flowers seem to be more complex in the Japanese than Vietnamese population. The percentage of each flower anthocyanin was very low except for two major anthocyanins found in all Vietnamese and Japanese accessions. It was not possible to classify the Vietnamese and Japanese populations by flower anthocyanin constituents. The two major anthocyanins found in all accessions of R. simsii flowers in Vietnam and Japan were isolated and purified by column and high-performance liquid chromatography. Their structures were elucidated by ¹H-NMR spectroscopic analyses and either acid or alkaline hydrolysis, and they were identified as cyanidin 3-galactoside and cyanidin 3-arabinoside. These two anthocyanins seem to be common to red-flowered evergreen azaleas, such as R. indicum, R. kaempferi, R. oldhamii, and R. scabrum.

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Shiikuwasha (Citrus depressa Hayata) and other endemic citrus fruits have been cultivated for several hundred years in the Ryukyu Islands. Citrus fruits contain high levels of functional phytochemicals, including specific and appealing aroma compounds. We analyzed the volatile compounds in immature and mature peel of 10 citrus fruits grown on Okinawa by GC-MS analysis. In addition, we used HPLC to quantify synephrine and six polymethoxyflavones (PMFs: sinensetin, hexamethoxyflavone, heptamethoxyflavone, nobiletin, natsudaidain, and tangeretin). All local citrus cultivars showed unique aroma profiles. The volatile compositions of ‘Kabuchii’ (C. keraji hort. ex Tanaka var. kabuchii) had high contents of sesquiterpene hydrocarbons (3.90–5.17%), ‘Keraji’ (C. keraji hort. ex Tanaka) was high in esters (12.15–19.10%), and ‘Ogimikuganii’ (C. depressa Hayata) was high in γ-terpinene (21.17–29.60%) and p-cymene (6.49–9.84%). The highest levels of synephrine were found in immature peel of ‘Tokunibu’ (C. nobilis Lour.) (8.97 mg·gDW⁻¹), ‘Izumibeni’ (C. tangerina hort. ex Tanaka) (7.03 mg·gDW⁻¹), and ‘Ogimikuganii’ (5.17 mg·gDW⁻¹). There were high levels of PMFs in immature peel of ‘Ogimikuganii’ (20.62 mg·gDW⁻¹), ‘Kabuchii’ (20.66 mg·gDW⁻¹), ‘Oto’ (C. oto hort. ex Yu. Tanaka) (12.52 mg·gDW⁻¹), and ‘T-132’ (C. tankan Hayata) (18.95 mg·gDW⁻¹), each of which showed a unique profile. Our results suggested the scope for effective utilization of the waste, including thinned fruits, from shiikuwasha and tankan, that major cultivars in Okinawa.

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