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  • Author or Editor: Keizo Yonemori x
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Abstract

Transpiration rate, stem diameter, and leaf temperature of satsuma mandarin (Citrus unshiu Marc.) were found to be sensitive indicators of stomatal response to ozone exposure. Time of reaction of each to 1.2 ppm ozone was 3 min. Stem diameter showed marked oscillation and leaf temperature slight oscillation, when ozone was applied. Correlation coefficiennt between ozone concentration and transpiration rate at the equilibrium status after the beginning of exposure was r = 0.718, and increasing the concentration of ozone decreased stomata size. Thus, it was determined that low sensitivity of satsuma mandarin to ozone is due to rapid stomatal closure by ozone.

Open Access

Abstract

Tannin cells from fruit of Japanese persimmon (Diospyros kaki L.) cvs. Fuyu [pollination-constant and nonastringent (PCNA)], Chokenji [pollination-variant and nonastringent (PVNA)], Hiratanenashi [pollination-variant and astringent (PVA)], and Kuramitsu [pollination-constant and astringent (PCA)], were observed by florescence microscope (FM) and scanning electron microscope (SEM) on 4 July, when all cultivars were very astringent, and on 5 Sept., when ‘Fuyu’ and ‘Chokenji’ fruit had completely lost their astringency. ‘Hiratanenashi’ and ‘Kuramitsu’ fruit, however, were still quite astringent on the latter date. FM observations on 4 July indicated that tannin cells of all fruit possessed some discontinuous portions in the cell walls. SEM observations of fractured surfaces of fruit flesh verified the existence of pores in the tannin cell walls. Moreover, coagulated internal contents of tannin cells (caused by the fixatives) had protruded through the pores. On 5 Sept., however, the pores in tannin cell walls of ‘Fuyu’ and ‘Chokenji’ were not present, and the surface of coagulated internal contents had become smooth. ‘Hiratanenashi’ and ‘Kuramitsu’ fruit on 5 Sept. showed little change in the structure from that observed on 4 July. Pore occlusion occurred in ‘Hiratanenashi’ fruit that were treated on the tree with ethanol fumes to remove astringency, which indicates that loss of astringency induces structural changes in tannin cell walls.

Open Access

Abstract

Morphological changes in tannin cells were observed in ‘Fuyu’ [pollination-constant and nonastringent (PCNA)] and ‘Hiratanenashi’ [pollination-variant and astringent (PVA)], two of the four types of Japanese persimmon fruit (Diospyros kaki L.). Pores in the tannin cell walls of ‘Fuyu’ started to occlude on 24 July when cell enlargement had ceased. This occlusion coincided with cessation of tannin accumulation, as determined by soluble tannin content and fresh weight of fruit. The pores were almost completely occluded on 7 Aug. Pore occlusion preceded the coagulation of tannins. In ‘Hiratanenashi’, pores in the tannin cell walls expanded until 7 Aug. When enlargement of tannin cells ceased on 14 Aug., occlusion of the pores in the cell walls was initiated. This event also nearly coincided with cessation of tannin accumulation. The process of occlusion was much slower than in ‘Fuyu’ and was about complete on 16 Oct. Thus, the pores in the tannin cell walls appear to be involved in tannin accumulation.

Open Access

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.

Free access

The phylogenetic relationships among 17 Garcinia species including G. mangostana (mangosteen) were analyzed by comparing sequences of the internal transcribed spacer (ITS) region of nuclear ribosomal DNA (nrDNA). Both parsimonious and neighbor joining (NJ) analyses revealed that G. mangostana is closely related to G. malaccensis believed to be a progenitor of mangosteen. Another suspected progenitor of mangosteen, G. hombroniana, was more distant from G. mangostana than G. malaccensis phylogenetically. Garcinia hombroniana formed a cluster with G. rostrata, G, speciosa and G. sizygiifolia, and this cluster was connected with a cluster of G. mangostana and G. malaccensis. The ITS sequence analysis showed that G. atroviridis, G. cowa, G. dulcis, G. malaccensis, G. mangostana, G. rostrata and G. vilersiana have nucleotide additivity (two different nucleotides at the same nucleotide position) at several sites in the ITS region. The occurrence of these species might be related to hybridization with ancestors, but the genomic compositions, even chromosome numbers, of these species are still unknown.

Free access

A method for collecting the vacuolar contents of intact tannin and parenchyma cells of persimmon (Diospyros kaki Thunb.) fruit using a micropipette was developed. Thin sections of the mesocarp tissue from mature persimmon fruit, `Miyazaki-mukaku' and `Hiratanenashi', were placed on a glass slide. Using a micromanipulator and an inverted microscope, a micropipette was inserted into a vacuole and its contents were withdrawn. A 5-nL sample of vacuole sap was collected per tannin cell from `Hiratanenashi' and 7 nL from `Miyazaki-mukaku', whereas only 2 nL was withdrawn from adjacent parenchyma cells. Analyses of the vacuolar sap revealed that the tannin cells of both cultivars contained 10% to 12% (m/v) of tannin as (+)-catechin equivalents and 10% to 13% (m/v) of soluble sugars, whereas the parenchyma cells contained trace amounts of tannins and ≈20% of soluble sugars. Tannin cells contain only a slight amount of sucrose, in contrast to a relatively large amount in parenchyma cells.

Free access

To understand the molecular basis of the endodormancy of buds of perennial plants, we searched for the genes that are expressed preferentially in endodormant lateral buds of the deciduous fruit tree japanese apricot (Prunus mume Sieb. et Zucc.) using suppression subtractive hybridization with mirror orientation selection (SSH/MOS). We generated two SSH/MOS libraries containing gene pools that are expressed preferentially in endodormant buds in comparison with paradormant or ecodormant buds to search for the genes that are upregulated by endodormancy induction or down-regulated by endodormancy release, respectively. Differential screening and sequencing indicated that genes involved in gibberellin metabolism, stress resistance, cell wall modification, and signal transduction, such as transcription factors, are upregulated in endodormant buds. After a further expression survey and full-length cDNA cloning, we found that a gene similar to the SVP/AGL24-type MADS-box transcription factor showed endodormancy-associated expression. Seasonal expression analysis suggested that the SVP/AGL24 homolog in japanese apricot might be involved in endodormancy regulation of its lateral buds.

Free access

Expression patterns of the genes involved in condensed tannin (CT) biosynthesis during fruit development was investigated in a Chinese pollination-constant, nonastringent (PCNA) persimmon (Diospyros kaki Thunb.) `Luo Tian Tian Shi'. The transcript levels of phenylalanine ammonia-lyase (PAL) and dihydroflavonol reductase (DFR) in `Luo Tian Tian Shi' were detected at high levels throughout the fruit growth. Chalcone synthase (CHS) and flavonol 3-hydroxylase (F3H) also continued to be transcribed during fruit growth, although their levels decreased earlier than PAL and DFR. In contrast, expression levels of these genes declined into undetectable levels at an early stage of fruit development in Japanese PCNA persimmon. In addition, anthocyanidin reductase (ANR), which encodes a key enzyme of the proanthocyanidin biosynthesis, was transcribed at high levels in `Luo Tian Tian Shi' during fruit growth, but not in Japanese PCNA persimmon. By contrast, the expression of D. kaki serine carboxypeptidase-like protein 1 (DkSCPL1) that was obtained from suppression subtractive hybridization (SSH) analysis between artificially astringency-removed fruit and astringent fruit in a different experiment, declined earlier than the other flavonoid biosynthesis genes in `Luo Tian Tian Shi', coincident with the termination of the tannin cell development. In the F1 progeny of the cross between `Luo Tian Tian Shi' and Japanese PCNA `Taishu', similar expression patterns were obtained among segregated PCNA and astringent offspring. These results indicate that Chinese PCNA is different from Japanese PCNA in expression of the genes involved in CT biosynthesis. In conclusion, we clarified that expression of the genes (PAL to ANR, but not SCPL) involved in flavonoid biosynthesis was continuous in the Chinese PCNA cultivar, despite the termination of tannin cell development.

Free access

5S ribosomal DNA (rDNA) was visualized on the somatic metaphase chromosome of persimmon (Diospyros kaki) and ten wild Diospyros species by fluorescent in situ hybridization (FISH). The digoxigenin (DIG)-labeled 5S rDNA probe was hybridized onto the chromosomes and visualized by incubation with anti-DIG-fluorescein isothiocyanate (FITC). Strong signals of 5S rDNA probe were observed on several chromosomes of Diospyros species tested. Furthermore, multicolor FISH using 5S and 45S rDNA probes differently labeled with DIG and biotin, revealed separate localization of the two rDNA genes on different chromosomes of Diospyros species tested, suggesting that 5S and 45S rDNA sites can be used as chromosome markers in Diospyros. The number of 5S rDNA sites varied with the Diospyros species. More 5S rDNA sites were observed in four diploid species native to Southern Africa than in three Asian diploid species. The former had four or six 5S rDNA sites while the latter had two. Three Asian polyploidy species had four to eight 5S rDNA sites. Among the Asian species, the number of 5S rDNA sites seemed to increase according to ploidy level of species. These features of 5S rDNA sites were very similar to those of 45S rDNA sites in Diospyros. Phylogenetic relationship between D. kaki and wild species tested are discussed based on the number and chromosomal distribution of 5S and 45S rDNA.

Free access

Flower bud differentiation and the flowering habit of durian (Durio zibethinus Murray) `Mon Thong' from budbreak to anthesis were investigated at the Chantaburi Horticultural Research Center in Thailand. Clusters of flower buds appeared at the end of November on primary or secondary scaffold branches near where a flower cluster occurred the previous year. Anatomical observations revealed that the development of floral organs was acropetal; the five fused epicalyx forming a large, elongated envelope enclosing the sepals, petals, stamen and fused multi-carpellate pistil. Floral organ development was completed in early January. The mature flower bud more than doubled in size one day before anthesis, with anthesis starting around 1600 hr and ending ≈1900 hr. The anthers did not dehisce until the completion of flowering. This change induced heterostyly in this cultivar, which promoted out-crossing by reducing the possibility of self-pollination. Aromatic nectar that attracted insects to the flower was secreted during anthesis. This is the first report to have clarified the overall flowering process in durian and provides the basic information for elucidating reproductive biology of durian in future research.

Free access