Cover Gallery

Cover Gallery

Vol.86 (2017)

Vol.86, No.4 (October 2017)

Sugars are related to fruit yield and quality by playing a critical role in fruit set, growth, ripening, and composition. Not only is tomato (Solanum lycopersicum) an important horticultural crop, it is also a useful experimental model plant. In this issue (pp. 417―425), Kanayama reviews current topics in sugar metabolism and fruit development in tomato, including the use of tomato introgression lines to investigate the control of sugar content, the regulation of sugar metabolism in relation to sugar sensors and signaling, and the roles of proton pumps, sugars, and auxin in fruit set and early fruit development. On the cover, proposed models are shown for the increased sugar and amino acid contents in fruit of IL8-3, a tomato introgression line, and for the roles of sugars and auxin in fruit set and early fruit development. The trade-off between fruit sugar content and yield, and the factors involved in sugar sensing and signaling are discussed as well in this review article.
(Provided by Y. Kanayama: Tohoku University)

Vol.86, No.3 (July 2017)

Lily is one of the most popular flowers and Japanese lilies are important genetic resources for breeding. Lilium auratum var. auratum Lindl. is distributed in the eastern part of Honshu, the main island of Japan. L auratum var. platyphyllum Baker is endemic to the Izu archipelago, which consists of nine large islands located in south of Honshu’s Izu peninsula. L. auratum var. platyphyllum has larger flowers and wider leaves than L. auratum var. auratum. L. auratum var. platyphyllum has yellow spots, whereas L. auratum var. auratum has red or brown ones. Natural hybridization between these two taxa has been suggested on the basis of spot colors of populations in the Izu archipelago and the Izu peninsula. However, their genetic diversity and hybridity in nature have not been reported. Morphological and SSR analyses revealed that L. auratum var. auratum and L. auratum var. platyphyllum are genetically different and that L. auratum var. platyphyllum has genetic diversity among populations in the archipelago. (pp. 379―388)
(Provided by S. Yamamoto : Meiji University)

Vol.86, No.2 (April 2017)

TBreeders and growers are tasked with the production of seedless fruit to meet consumer demand in citriculture. Satsuma mandarin (Citrus unshiu Marc.) is considered to be absolutely seedless because it has both female and male sterility with parthenocarpy. A previous study identified two GA 20-oxidase genes in Satsuma mandarin and confirmed their function using transgenic Arabidopsis. Consistent with the accumulation of active GAs in the ovaries around anthesis, CuGA20ox2 is specifically expressed in the flower bud immediately before anthesis in Satsuma mandarin. In this issue (pp. 183-193), Kotoda et al. characterized Satsuma mandarin GA 2-oxidase genes that encode enzymes with GA inactivation activity, and showed that CuGA2ox4, CuGA2ox2/3, and CuGA2ox8 were differentially expressed in various tissues in Satsuma mandarin and that these genes functioned like GA 2-oxidase genes in transgenic Arabidopsis
(Provided by N. Kotoda: Saga University).

Vol.86, No.1 (January 2017)

The consumption of vegetables and fruits rich in potassium (K), such as melon and strawberry, is restricted in chronic kidney disease (CKD) patients. Therefore, we attempted to produce low-K strawberry through the management of KNO3 concentration in nutrient solution applied from anthesis to harvest period. In this issue (pp. 26-36), Mondal et al. observed a general trend of decreasing K content in four strawberry cultivars with the decrease of KNO3 concentration in the nutrient solution. ‘Toyonoka’ fruit exhibited a K reduction of approximately 64% when plants were grown in nutrient solution containing KNO3 at 1/16 of the normal level. Citric acid and ascorbic acid contents in ‘Toyonoka’ fruit were reduced with decreasing KNO3 concentration in the nutrient solution. Although the reduced NO3− in the nutrient solution was adjusted by adding Ca(NO3)2 to grow low-K strawberry, both yield and quality did not vary with this adjustment. Fruit K content was decreased by 43% and 54% in plants grown in nutrient solution containing 1/8 and 1/16 of the normal level of KNO3, respectively.
(Provided by T. Asao, Shimane University)

Vol.85 (2016)

Vol.85, No.4 (October 2016)

Prunus fruit tree species exhibit S-ribonuclease (S-RNase)-based gametophytic self-incompatibility (GSI). The S-RNase-based GSI system is also found in families Plantaginaceae and Solanaceae and tribe Maleae in family Rosaceae. In these plant taxa, S-RNase and F-box protein are commonly identified as pistil and pollen S determinants, respectively. Interestingly, Prunus GSI was gradually recognized to show distinct features, which is indicated to be attributable to the different molecular functions of its pollen S determinant (S haplotype-specific F-box protein, SFB). It has been suggested that SFB functions in inducing self S-RNase cytotoxicity within pollen tube cytoplasm to inhibit pollen tube growth in self styles, in contrast to pollen S determinant F-box proteins in non-Prunus taxa that function in the detoxification of non-self S-RNases to maintain pollen tube growth in non-self styles. In this issue (pp. 289-305), Matsumoto and Tao summarize the characteristics of Prunus S-RNase-based GSI with references to those of non-Prunus taxa, and suggest a working model for its distinct self/non-self discrimination mechanism.
(Provided by R. Tao: Kyoto University)

Vol.85, No.3 (July 2016)

Next to standard-type chrysanthemum production, the production of cut flowers of small-flowered spray-type chrysanthemum is the largest in Japan, exceeding that of rose or carnation. Because small-flowered spray-type chrysanthemums are used in many religious festivals, their demand increases in certain months of the year. Sales of these flowers in July to September account for about 40% of annual sales. During the high-demand months, summer-to-autumn-flowering small-flowered spray-type (SAFS) chrysanthemums are produced. Therefore, SAFS chrysanthemums are commercially important. However, under current cultivation methods, spray formation quality is compromised in order to maintain sufficient production during the months of peak demand for SAFS chrysanthemums. In this issue (pp. 264-271), Mori et al. showed that spray formation in SAFS chrysanthemum cultivars ‘Haruka’ and ‘Subaru’ could be regulated by controlling the timing and period of interrupted lighting. This technique would enhance the production of various types of spray formations while using the same cultivar, thereby allowing growers to meet various demands while using only a few cultivars. This would stabilize the production of SAFS chrysanthemum cut flowers.
(Provided by Y. Mori: Okayama Prefectural Technology Center for Agriculture, Forestry and Fisheries)

Vol.85, No.2 (April 2016)

Bicolor flowering dahlia (Dahlia variabilis) consists of cultivars having petals with colored bases and white tips. A prominent feature of bicolor dahlia cultivars is the lability, or instability, of petal colors: Instead of producing the original bicolor petals, the cultivars frequently produce single-colored petals without white tips. The red–white bicolor flowering cultivar ‘Yuino,’ which predominantly produces inflorescences with only bicolor petals, often produces inflorescences with only red petals or mixed inflorescences with both red petals and bicolor petals. In this issue (pp. 177-186), Ohno et al. reveal a strong relationship between inflorescence color and flavonoid accumulation in leaves: red-petal-producing plants accumulated flavonoids in leaves, whereas plants producing only bicolor petals tended to not accumulate flavonoids in leaves. This indicates that petal color lability can be interpreted as a phenotypic change at the whole-plant level.
(Provided by S. Ohno : Kyoto University)

Vol.85, No.1 (January 2016)

Cytoplasmic male sterility (CMS) is a useful system for hybrid seed production in crop species. In eggplant, CMS systems have been developed utilizing the cytoplasm of wild Solanum species by repeated backcrossing. The CMS systems are classified into two types. The first one is anther indehiscent-type sterility (second from left of bottom photographs) in which anther contains normal pollen but does not open to release. The second one is pollen non-formation-type sterility (fourth from left of bottom photographs) in which anther of male-sterile lines is completely devoid of pollen. In this issue (pp. 1–7), Khan and Isshiki describe cytoplasmic male sterility in eggplant, focusing on its development, characterization, and fertility restoration, as well as the development of a SCAR marker linked to Rf genes.
(Provided by S. Isshiki : Saga University)

Vol.84 (2015)

Vol.84, No.4 (October 2015)

Transposable elements (TEs) are mobile genetic elements in the eukaryotic genome. TEs are divided into class I (retrotransposons) and class II (DNA transposons). Retrotransposons are especially abundant in higher plant genomes. As retrotransposon insertions with high copy numbers are dispersed throughout these genomes and are inherited genetically, insertion polymorphisms among crop cultivars have been used as molecular markers. Recently, we have developed an efficient method of screening long terminal repeats (LTRs) of retrotransposon families that exhibit high insertion polymorphisms among crop cultivars using a next-generation sequencing (NGS) platform. In addition, we have identified the insertion sites of these identified retrotransposon families on the genome-wide scale in several cultivars with a NGS platform, which enabled us to acquire several molecular markers for DNA genotyping. Among these insertion sites, cultivar-specific insertion sites can be utilized as molecular markers for cultivar discrimination. Our results indicated that the targeted sequencing of retrotransposon insertion sites was highly effective for DNA genotyping and marker development without requiring any whole-genome sequence information. In our review (pp. 283–294), we describe the development of retrotransposon-based molecular markers with the NGS platform in several plant species such as strawberry, citrus, apple, and sweetpotato.
(Provided by Y. Monden: Okayama University)

Vol.84, No.3 (July 2015)

Light and temperature are important environmental factors that affect flavonoid accumulation in grape berry skin. However, the components of light signaling and low-temperature-induced abscisic acid (ABA) signaling networks related to flavonoid biosynthesis have not been fully elucidated. In this issue (pp. 214–226), Azuma et al. discuss how they utilized a grape oligo-DNA microarray (38,549 independent probes) that adopts the publicly available genomic sequence of grape to perform a comprehensive transcriptome analysis of detached grape berries cultured under different light and temperature conditions. Using microarray data, the authors identified 40 light-inducible genes, 55 low-temperature-inducible genes, and 34 light- plus low-temperature-inducible genes. From the expression characteristics of three candidate genes, the authors hypothesized that elongated hypocotyl 5 (HY5), open stomata 1 (OST1), and enhanced response to ABA 1 (ERA1) might be involved in flavonoid biosynthesis via light signaling and low-temperature-induced ABA signaling. In addition, the extensive catalog of gene expression patterns defined in their study will support future investigations of other grape berry skin candidate genes that respond to light and temperature.
(Provided by  A. Azuma: NARO Institute of Fruit Tree Science)

Vol.84, No.2 (April 2015)

Genetic transformation approaches have been taken for the functional analyses of cloned genes involved in flavonoid biosynthesis. In such studies, both homologous and heterologous plants have been used as hosts for the genetic transformation. Examples include petunia, torenia, Nicotiana, and Arabidopsis. In this issue (pp. 131–139), Takatori et al. utilized Ipomoea nil (Japanese morning glory) as the heterologous host for the transgenic complementation (right) of the flavonoid 3′-hydroxylase (F3′H) gene cloned from Eustoma grandiflorum (lisianthus; upper left), because an authentic magenta mutant of this species, I. nil ‘Violet’ (lower left), has a deficient F3′H gene. The authors demonstrated that the lisianthus F3′H gene encodes a functional flavonoid 3′-hydroxylase. In addition, their study underscored the use of I. nil as a valuable model organism for molecular genetic studies of flower pigments. This is the first report of both the cloning of the lisianthus F3′H gene and the transgenic complementation using a heterologous host of Japanese morning glory carrying a mutant allele of the corresponding gene.
(Provided by  K. Shimizu: Kagoshima University)

Vol.84, No.1 (January 2015)

The carnation is a very popular gift on Mother’s Day and other occasions. Along with chrysanthemum and rose, carnation is one of the most commercially important ornamental crops in Japan and around the world. To produce new cultivars efficiently and speed up breeding, linkage analysis and the development of markers for bacterial wilt resistance derived from line 85-11 and Dianthus capitatus ssp. andrzejowskianus had been conducted (lower). Recently, the genome sequencing of ‘Francesco’ (upper left), the leading carnation cultivar in Japan, was conducted and the results were made available in the sequence database (upper right). In this issue (pp. 3–13), Yagi describes recent advances in the genome analysis of ornamental plants, with focus on carnation. Genome sequencing analysis of other ornamentals is expected in the near future. Such advances mark the beginning of a new era in the breeding of ornamentals.
(Provided by M. Yagi: NARO Institute of Floricultural Science)

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