Photoassimilates needed for fruit development are supplied from leaves, converted in fruit to substances relating to the specific quality of the fruit, then accumulate in the fruit. There are various regulation steps in the process from photoassimilate synthesis in leaves to sugar accumulation in fruit: photosynthesis, synthesis of translocation sugars, loading of translocation sugars, their translocation, their unloading, their membrane transport, their metabolic conversion, and compartmentation in vacuoles. Thus, it is important to clarify the mechanism and regulation of each step in fruit development. In this review, mainly the metabolic conversion of translocation sugars and their regulation at the genetic level in fruit are described because the metabolic conversion in fruit contributes greatly to produce the sink activity needed for fruit development.

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In order to produce new seedless kumquat cultivars, we carried out an intergeneric cross between ‘Kiyomi’ tangor [Citrus unshiu Marcow. × C. sinensis (L.) Osbeck] and Meiwa kumquat (Fortunella crassifolia Swingle), obtaining 2 normal seeds and 7 undeveloped seeds. These seeds were cultivated on Murashige and Tucker medium, and the 2 normal seeds germinated and developed. The results of genome size analysis by flow cytometry revealed that both seedlings were triploids and that the difference in genome size corresponded to more than one chromosome in the 2 seedlings. Chromosome observation confirmed diploid (2n = 2x = 18) in both parents, aneuploid with 28 chromosomes (2n = 28) for one of the seedlings, and triploid (2n = 3x = 27) for the other seedling. Random amplified polymorphic DNA (RAPD) and cleaved amplified polymorphic sequence (CAPS) analyses proved that the seedlings were intergeneric hybrids between ‘Kiyomi’ tangor and Meiwa kumquat, with the maternal organelle genome. These hybrids have the potential to be released as a cultivar after further tree and fruit evaluations, and for use as cross-parents in seedless kumquat breeding.

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Fluorescent banding patterns of pear chromosomes were determined from samples taken from root tips of open-pollinated seedlings of six cultivars from three species [Pyrus pyrifolia (Burm. F) Nakai (Japanese pear), P. communis L. (European pear), and P. bretschneideri Rehder (Chinese pear)]. Root tips were pretreated in 2 mM 8-hydroxyquinoline at 10°C for 4 h; the chromosome samples were prepared by the enzymatic maceration and air-drying method. All cultivars used in this study had 2n = 34 chromosomes. Chromomycin A₃ (CMA) positive (+) bands were observed in telomeric positions of four chromosomes. In some samples, these CMA+bands were observed at satellite positions. 4'-6-diamidino-2-phenylindole (DAPI) negative bands (−) were seen to correspond with CMA+bands. Thirty chromosomes had no CMA+/DAPI−bands. No propidium iodide (PI) bands were observed in any chromosomes. The number and positions of CMA+bands were stable, and there was no difference among the three species.

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The correlation between the occurrence of internal browning (IB) and the size of root xylem parenchymatous cells in Japanese radish (Raphanus sativus L.) was determined in 3 experiments. The first examined intervarietal differences in IB among 5 commercial cultivars (cvs.). Results revealed that the differences in susceptibility to IB largely depend on root cell size, and that mean cell length in IB-resistant cvs. was approximately 39–45% shorter than in susceptible cvs. The second experiment examined the relationship between cell size and IB occurrence in 3 IB-susceptible commercial cvs. and their ‘Gensuke’ F₁ hybrids. In every F₁ hybrid strain, the central region did not appear to show the propensity of its parents to develop IB, and mean cell length in the former was approximately 26–39% shorter than in the latter. The third experiment examined the effect of applying a plant growth regulator on IB occurrence and cell size. Gibberellin (GA) application during the mid-growth stage restricted IB occurrence, and the mean cell length of GA-treated plants during this period was approximately 27–47% shorter than in the control. These results strongly suggest that IB occurrence is largely dependent on the size of root xylem parenchymatous cells, and IB seldom occurs in roots with smaller cells.

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Environmental dependence of male sterility may sometimes result in residual fertility under ‘sterility conditions’, causing hybrid-seed contamination risk. An experiment was conducted to assess the risk factor and methods to increase hybrid-seed purity in a thermosensitive male-sterile tomato mutant, T-4, whose fertility is partially restored in autumn, but largely remains sterile in spring, with some residual fertility. Examination of pollen germination and the subsequent pollen-tube growth in vitro and on stigma revealed that a small proportion of the T-4 pollen was viable, with 10–20% germination, while normal pollen from ‘Tiny Tim’ had 60–85% germination 3–6 h after pollination. A stable male-sterile mutant T-3, whose pollen development collapses at the microspore stage, was pollinated with T-4 pollen followed by normal ‘Tiny Tim’ pollen with time lags of 2, 4, and 8 h. Concurrently, the T-4 mutant was self-pollinated by hand followed by normal pollen from an inbred line (M) with time lags of 2, 4, 8, 24, and 48 h. The progeny was scored for contamination based on differences in leaf characteristics. The percentage of T-4 seedlings (narrow leaved) in the F₁ progeny was lowest at 2 h (0.2–6.3%), highest at 8 h (16.9–17.7%) and declined at 24 h–48 h (13.5–10.3%) time lag. The contamination rate was extremely low when pollination was done with normal pollen at (0.4%) and 24 h after (1.4%) anthesis without prior hand pollination with T-4 pollen. It was concluded that with pollination timing soon after anthesis, the T-4 mutant could be effectively applied in a two-line hybrid-seed production system with lower roguing cost of undesirable seedlings as opposed to the conventional three-line system.

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The objectives of this study were to determine the effects of UV spectra (broad UV 274–400 nm, B-UV or filtered UV 286–400 nm, F-UV) and irradiation timing (at day or night) on growth inhibition and seedling injury in plug-transplants of pepper (Capsicum annunm L. ‘Nogkwang’) and tomato (Solanum lycopersicum, ‘Pinktop’). We investigated some parameters, to clarify the plant response, such as ion leakage, lipid peroxidation, chlorophylls, careotenoids, photochemical efficiency, UV absorbing compound, plant growth, and flowering. The results showed that irradiation of B-UV at night significantly inhibited plant height and total leaf area in two species. However, it caused seedling injuries such as leaf necrosis and bloomlessness regardless of irradiation timing. While irradiation of F-UV did not cause any seedling injury regardless of irradiation timing, it significantly inhibited plant height by 25.4% in pepper and by 26.1% in tomato. Our results suggest that irradiation of F-UV at night may be desirable to control excessive stem elongation in plug-transplants during summer, in addition to being safe to the grower.

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We compared the effects of quantitative control in closed system versus electrical conductivity (EC)-based control in open system of nutrients on the growth and yield of tomatoes in rockwool cultivation. Quantitative control supplied all nutrients once a day based on criteria for three application rates (1.0 ×, 1.25 ×, and 1.5 × the standard). These criteria were previously developed in the deep flow technique (DFT) to estimate their nutrient requirements, which used the three-day average amount of water absorbed by tomato plants. We compared the quantitative control in a closed system with two EC treatments in an open system, in which we supplied nutrient solution at high and low EC ranges. The 1.0 × quantity standard reduced the nutrient supply to 30–37% of the levels used in the low-EC treatment. N, P, and K concentrations in the 1.0 × substrate solution remained low and stable for two months after transplanting. The 1.0 × treatment had 27% lower total leaf dry weight and 23% higher total fruit yield than the low-EC treatment. However, greatly reduced growth and nitrogen content of upper leaf and slightly lower soluble solids content in the fruits suggest that the 1.0 × standard might provide insufficient nutrients during late growth stages. Excessive nutrient supplies, which were much lower than the low-EC treatment, increased substrate salinity owing to the accumulation of nutrients during the latter half of the growth period in the 1.25 × and 1.5 × treatments. The stable EC and nutrient concentrations in the 1.0 × substrate solution over time suggest that the three-day adjustment interval would be short enough. The quantity criteria developed for the DFT system could generally be applied to long-term rockwool culture, but the optimum range of nutrient supply was found to be from 1.0 × to 1.25 × the DFT standard in the later growth stages.

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A quantitative trait locus (QTL) analysis of pepper growth traits was performed using a doubled haploid (DH) population derived from a cross between two Capsicum annuum genotypes, a bell-type cultivar ‘California Wonder’ and a Malaysian small-fruited cultivar ‘LS2341’. Simple sequence repeats and amplified fragment length polymorphism markers were used to construct a genetic map for this population. The map spans 1,213 cM, and consists of 15 linkage groups (LGs). The axillary shooting, flowering date, primary axis length, number of leaves on primary axis and mean internode length were evaluated in 94 F₁DH families. Twelve QTLs were identified by interval analysis, and each QTL accounts for 14 to 34% of the phenotypic variation. Markers on chromosomes 2, 3, 12, and linkage group 8 (LG8) were associated with QTL for these traits. The present analysis revealed 2 loci for the growth traits in LG 8. One affected mainly axis length and had a minor effect on flowering, while the other had a large effect on flowering date and a smaller effect on axis length.

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Cuttings of cucumber (Cucumis sativus L.) grafted onto squash (Cucurbita moschata Duch.) rootstock using a hole-insertion graft were warmed at the hypocotyl of the rootstock in a cold chamber for acclimatization: they were soaked in water held at 31°C from the basal cut-end to the graft union at an air temperature of 12°C for 2 days. Warmed cuttings were planted and grown in an acclimatization chamber for 5 days. Control cuttings were planted immediately after grafting and grown in the chamber for 7 days. The fresh weight of the control scions decreased 2 days after grafting as a result of reduced water content, but that of warmed scions did not decrease. The fresh and dry weight of the warmed scions was 2.2 and 1.6 times that of the control, respectively, at 7 days after grafting. The graft development of warmed and control cuttings, evaluated based on the tensile strength, improved to a similar degree. The leaf conductance and chlorophyll fluorescence ratio (F_v/F_m) of the warmed scions, both of which indicate the degree of water stress, improved compared to those of the control at 7 days. These results demonstrate that the warming treatment does not adversely affect graft development but does reduce water stress at low air temperature during early acclimatization, and therefore improves early growth.

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Rooftop gardening or green roof establishment, one of the afforestation methods for urban greening, has many benefits for the environment, economy, and urban landscape. Various environmental stresses including heat, strong wind, sunshine and drought prevent most plants from growing well with extensive green roof systems. For the establishment of urban rooftop gardening in summer, we evaluated ten ornamental plant species (Evolvulus pilosus, Fragaria × ananassa, Hedera helix, Lampranthus spectabilis, Ophiopogon japonicus, Pelargonium × hortorum, Petunia × hybrida, Thymus serphyllum, Verbena × hybrida, Vinca major) to use for greening with shallow soil (10 cm depth) on the flat rooftop of a four-story building. We measured the area increase in green coverage as a total growth rate, photosynthetic ability of detached leaves, stomatal conductance of an attached leaf, soil surface and canopy air temperature. Thymus, Evolvulus, Petunia, and Fragaria are excellent plant species for rooftop gardening judging from their speedy green coverage with high growth rates (90% in Thymus, 65% in Evolvulus, 60% in both Petunia and Fragaria at maximum for about three months in summer). Thymus and Fragaria showed high performance of water saving with relatively low stomatal conductance under semi-dry conditions and did not need to be replanted every year unlike Evolvulus and Petunia. Evolvulus had the highest photosynthetic activity at 40°C. Petunia and Verbena did not grow continuously but maintained active blooming without increasing their green coverage (about 60%) throughout midsummer. Lampranthus tolerated extremely hot and dry conditions on the rooftop but grew very slowly. As Vinca and Pelargonium died back due to both heat stress and strong wind, we suggested these were not suitable for rooftop gardening. All vegetations showed a 6–8°C lower temperature of soil surface than that of the concrete rooftop during summer nights. We concluded that rooftop greening has a significant effect on cooling a building and saving energy for air-conditioning in summer.

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The wabisuke camellia ‘Tarokaja’ is a very old cultivar of unknown origin. Based on morphological properties, it is thought to be an interspecific hybrid between Camellia japonica and an unidentified species from continental China. We analyzed chloroplast DNA from members of the genus Camellia to trace the maternal origin of ‘Tarokaja’. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of the atpI-atpH spacer region using 57 progeny derived from 17 interspecific crosses confirmed that chloroplast DNA is inherited maternally in the genus Camellia. Based on PCR-RFLP and sequence analyses of the atpI-atpH region and referring to knowledge about morphological properties, we concluded that the maternal origin of ‘Tarokaja’ is a Chinese native species C. pitardii var. pitardii. Wabisuke camellia cultivars are classified into two groups. One group of wabisuke camellia cultivars is thought to be derived from crosses between ‘Tarokaja’ and C. japonica. Since most of them had a ‘Tarokaja’-type single-base in the atpI-atpH region, it was confirmed that these wabisuke cultivars are descended from ‘Tarokaja’. It is likely that ‘Hime-wabisuke’, ‘Kocho-wabisuke’, and ‘Sukiya’, which had a C. japonica-type single-base, are progeny descended from ‘Tarokaja’ with C. japonica as the maternal ancestor. Another group of wabisuke camellia cultivars is thought to be derived from C. japonica by mutation, and all but one of these had a C. japonica-type single-base. The exception, ‘Kibi’, had a ‘Tarokaja’-type single-base, so that ‘Kibi’ is inferred to be descended from ‘Tarokaja’.

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Six acylated pelargonidin 3-O-sambubioside-5-O-glucosides were isolated from red-purple flowers of Lobularia maritima (L.) Desv. ‘Easter Bonnet Deep Rose’. These pigments were determined by chemical and spectroscopic methods to be pelargonidin 3-O-[2-O-(2-O-(acyl-II)-β-xylopyranosyl)-6-O-(acyl-I)-β-glucopyranoside]-5-O-β-glucopyranoside, in which the acyl-I group was replaced by 4-O-glucosyl-p-coumaric acid, p-coumaric acid or ferulic acid, and acyl-II by caffeic acid or ferulic acid, respectively. In comparison with the floral anthocyanins of purple-violet flowers in L. maritima cultivar ‘Easter Bonnet Violet’, the molecular composition of organic acids and sugars of ‘Easter Bonnet Deep Rose’ were identical, however, aglycones of both cultivars were different, and pelargonidin is the floral anthocyanin of ‘Easter Bonnet Deep Rose’ and cyanidin is that of ‘Easter Bonnet Violet’. Variations of the flower colors of these cultivars are responsible for the aglycone component in their floral anthocyanins. In this paper, the relation between flower color and anthocyanins in L. maritima cultivars is discussed.

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In intersubgeneric crosses of diploid evergreen azaleas (EV) × diploid Rhododendron japonicum f. flavum (JP), many progenies become albino as a result of plastome-genome incompatibility between a plastid genome from EV and a nuclear genome from JP. To clarify the mechanism of the incompatibility, inter- and intra-ploid crosses of diploid (2x) EV × diploid (2x) JP, tetraploid (4x) EV × tetraploid (4x) JP, 2x EV × 4x JP, and 4x EV × 2x JP were conducted. Seeds were obtained in all crosses, although the number of progenies per capsule was relatively low in crosses with 4x JP as a pollen parent. Plastome-genome incompatibility between a plastid genome from EV and a nuclear genome from JP was observed in progenies from 2x EV × 2x JP, 4x EV × 4x JP, and 2x EV × 4x JP, but not in 4x EV × 2x JP. This result indicates that plastome-genome incompatibility was broken by relative increase of the genome from EV in the nuclear genome of progenies.

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In carnation flowers, high temperatures have been shown to inhibit the induction of autocatalytic ethylene production and petal wilting. In this study, we investigated the effect of high temperature on ethylene production and petal wilting in carnation flowers after initiation of autocatalytic ethylene production. Transferring carnation flowers to high-temperature conditions (38°C) following the initiation of ethylene production by exposure to exogenous ethylene suppressed the autocatalytic increase in ethylene production. High-temperature treatment also depressed ethylene production in carnation flowers producing high levels of ethylene. In petals of these flowers held at 38°C, 1-aminocyclopropane-1-carboxylate synthase (ACS) and 1-aminocyclopropane-1-carboxylate oxidase (ACO) activities were depressed with greater depression in ACS activity; however, the progression of petal wilting was not suppressed in high-temperature-treated flowers. These results indicate that high temperature depresses ethylene production but has little effect on petal wilting in carnation flowers once ethylene production has been initiated.

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Four new acylated cyanidin glycosides were isolated from the purple root peers of Raphanus sativus L. ‘Benikanmi’, along with five known anthocyanins. These pigments were based on cyanidin 3-sophoroside-5-glucoside, and acylated diversely with malonic, p-coumaric, caffeic, and ferulic acids. Two pigments of these four new anthocyanins were determined to be cyanidin 3-O-[2-O-(β-glucopyranosyl)-6-O-(trans-feruloyl)-β-glucopyranoside]-5-O-[6-O-(malonyl)-β-glucopyranoside] and cyanidin 3-[2-(glucosyl)-6-(cis-p-coumaroyl)-glucoside]-5-[6-(malonyl)-glucoside] by chemical and spectroscopic methods. Since two other new pigments were obtained in small quantities, their structures were tentatively assigned to be malonyl cyanidin 3-sophoroside-5-glucoside and malonyl cyanidin 3-[2-(glucosyl)-6-(trans-caffeoyl)-glucoside]-5-glucoside, mainly on the basis of their spectroscopic data. From the results, the potential of these purple root anthocyanins as natural food colorants is discussed.

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