Solanaceae, Rosaceae, and Plantaginaceae exhibit the S-RNase-based gametophytic self-incompatibility (GSI) system. This type of GSI is controlled by a single polymorphic locus (S locus) containing the pistil S determinant gene, S-ribonuclease (S-RNase), and the pollen S determinant, the S locus F-box gene (SFB/SLF). In addition to these determinant genes, non-S factors, called modifier genes, are required for the GSI reaction. Here, we conducted large-scale transcriptome analysis of unpollinated, self-pollinated, and cross-pollinated pistils of Japanese apricot (Prunus mume Sieb. et Zucc. cv. Nanko) to capture all of the molecular events induced by the GSI reaction in Prunus, using next-generation sequencing technologies. We obtained 40,061 unigenes from 77,521,310 reads from pollinated and unpollinated pistils and pollen grains. Among these unigenes, 29,985 and 27,898 unigene sequences showed at least one hit against the NCBI nr and TAIR10 protein databases, respectively, in BLASTX searches using an E-value cutoff of 1e-6. Digital expression analysis showed that 8,907 and 10,190 unigenes were expressed at significantly different levels between unpollinated (UP) and cross-pollinated (CP) pistils and between UP and self-pollinated (SP) pistils, respectively. The expression of 4,348 unigenes in both CP and SP pollination was commonly and significantly different from that in UP, while the expression of 4,559 and 5,842 unigenes in CP and SP, respectively, was specifically and significantly different from UP. The expression of 2,227 unigenes was up-regulated both in CP and SP compared with UP. Genes supposedly involved in S-RNase-based GSI were included among the unigenes up-regulated by pollination, while no unigenes homologous to the solanaceous pistil modifiers HT-B or 120K were included among the unigenes up-regulated by pollination or in the whole unpollinated/pollinated pistil transcriptome. We discuss the distinct molecular mechanism of S-RNase-based GSI in Prunus.

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The infection efficiency of Agrobacterium to cotyledon explants of Japanese apricot (Prunus mume) was markedly improved by sonication treatment. The use of sGFP(S65T) reporter gene in this study enabled direct observation of transgene expression, thus allowing the evaluation of Agrobacterium infection efficiency. Immature cotyledons of different cultivars and different developmental stages were subjected to sonication treatment of durations ranging from 10 sec to 2 min. When early-stage immature cotyledons of ‘Nanko’ were subjected to sonication treatment, the transient GFP expression frequency after co-cultivation was nearly 100% and GFP fluorescence was distributed over almost the entire cotyledon surface. In contrast, when the inoculation was carried out according to the standard dipping method, transient GFP expression frequency was less than 10% and GFP fluorescence was observed only in spots. The highest frequency of somatic embryogenesis (SEG) with GFP expression was obtained from 40 sec sonication treatment of May 14 ‘Nanko’ immature cotyledons. However, with younger cotyledons, which have a higher SEG frequency, 20 sec of sonication treatment was found to be sufficient to increase the infection frequency.

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Researchers have predicted that most of the current satsuma mandarin-producing regions will become unfavorable for growing this citrus crop by the 2060s owing to global warming. To offer satsuma mandarin growers information for making replanting decisions, we estimated future changes in locations suitable for the cultivation of tankan (Citrus tankan Hayata), the leading subtropical citrus in Japan. The results of fruit-freezing experiments suggested that the threshold air temperature for the cold tolerance of tankan fruit is about −2°C. The locations suitable for tankan were simulated on the basis of future annual mean air temperatures evaluated by the MIROC3.2-HiRes climate model under the SRES-A1B GHG emission scenario and future annual minimum air temperatures calculated from future daily minimum temperatures evaluated by this climate model and the current air temperature variability. The results of the simulation showed that most of the Pacific coastal area from the Kanto Plain and to the west will become suitable for tankan cultivation during 2031–2050, and that coastal areas of the current satsuma mandarin-producing regions in Japan should be suitable for tankan production by 2050. The inland area of southern Kyushu Island, despite its proximity to current tankan-producing regions, is predicted to experience temperatures causing a high frequency of cold injury to tankan fruits even during 2051–2070. Therefore, if satsuma mandarin production becomes difficult on account of increased global warming, tankan could be produced as a substitute in coastal areas of the current satsuma mandarin-producing regions. However, we predict that it will be difficult to produce tankan in inland areas of the current satsuma mandarin-producing regions.

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A recently popular Japanese yellow-green-skin table grape, ‘Shine Muscat’ (Vitis labruscana Bailey × V. vinifera L.), has the problem of berry skin browning, which occurs at the maturation stage just before harvest. Tiny reddish-brown blotches appear on the surface of berries and considerably decrease the grape’s market value. Although the mechanisms and factors for browning are unknown, we hypothesized the involvement of polyphenol compounds and their oxidation reactions. In this study, the gene expressions of polyphenol oxidase (PPO), stilbene synthase (STS), and chalcone synthase (CHS), which are key enzymatic genes related to the metabolic pathway for polyphenols, were analyzed during berry maturation to examine the molecular basis for browning. Skin browning occurred on several berries in a bunch of ‘Shine Muscat’ from 80 days after full bloom (DAFB), after which the number of berries with skin browning increased, and the browned area spread on the berry surfaces with maturation. Increases in the expression of VvPPO2, VvSTS type B, and VvCHS1 were associated with skin browning, and the trans-resveratrol content also increased in the browning skin, suggesting that biosynthesis and metabolic pathways for phenolic compounds were activated at the time of browning. In terms of VvPPO genes, specific up-regulation of VvPPO2 expression was observed compared with the VvPPO1 gene. The promoter sequence of VvPPO2 contains more Myb binding motifs and W-box motifs than does VvPPO1. The specific up-regulation of VvPPO2 gene expression will play a crucial role in understanding and managing the skin-browning mechanism in the grape berries of ‘Shine Muscat’.

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The aim of the research was to determine the impact of row covers on the growth, yield, and selected nutritional compounds contents in Chinese cabbage (Brassica rapa L. Pekinensis Group), cultivated in a field with or without non-woven fleece (17 g·m⁻²). Application of row covers accelerated the growth and development of the plants due to more favorable microclimatic conditions than in an open field. All tested biometrical parameters of the rosettes, determined after removing covers, were considerably higher than in the uncovered control. Therefore, direct covers could be successfully used for promote the growth of Chinese cabbage rosettes after transplanting. Total and marketable yields of covered plants were higher by 36% and 91%, respectively, than in the control. No external flower stalks were observed in either treatment, but about 50% of control heads had internal bolters. Row covering could be an effective prevention method against Chinese cabbage bolting in spring production in Central Europe. Laboratory analysis performed directly after removing covers showed higher contents of L-ascorbic acid, chlorophylls, and carotenoids in the plants in an open field. However, in the subsequent few weeks, such differences between treatments decreased and at harvest time, the level of these compounds was similar. Mature heads of control Chinese cabbage contained significantly more soluble sugars, crude fiber and thiocyanates than covered plants. The models were proposed to predict changes in fresh and dry weight as a function of time.

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This study analyzes and clarifies the eco-physiological traits of high-yielding strawberry (Fragaria ×ananassa Duch.) ‘Benihoppe’ focusing on its dry matter production, total nitrogen content, bleeding rate, mineral nutrient concentration in bleeding fluid, and fine root respiration rate in comparison with those of the cultivar ‘Sachinoka’. The results show that ‘Benihoppe’ has three beneficial characteristics. The first characteristic is higher primary and fine root dry matter and less root rotting during the cold season. The second is superior root function that includes high root activity and a well-maintained root system. The third is a high ability to absorb more NO₃⁻ and preferentially partition NO₃⁻ to the leaves, crowns, and fine roots. Thus, with these three beneficial functions, ‘Benihoppe’ may produce more dry matter and fruits than ‘Sachinoka’.

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A highly efficient and simple micropropagation system for Phalaenopsis was developed using elongated protocorm-like bodies (ePLBs) obtained by skotomorphogenesis. When normal protocorm-like bodies (nPLBs) without growing point excision were cultured under different light conditions (dark: 0 μmol·m⁻²·s⁻¹, low light: 2 μmol·m⁻²·s⁻¹, high light: 80 μmol·m⁻²·s⁻¹, of photosynthetic photon flux density respectively), PLB proliferation efficiency was higher under dark than high light and low light conditions. In addition, shoot formation percentage was lower under dark conditions (8.0%) than under low light (66.0%) and high light conditions (68.2%) and few PLBs developed shoots during culture under dark conditions. The Secondary ePLBs obtained after culturing under dark conditions were approximately twice as long as nPLBs. After acclimation under low light conditions for 2 weeks, the ePLBs were transferred to high light conditions after making a partial incision in their apical parts. Under high light conditions, a large number of secondary PLBs were obtained from ePLBs, 6 times as many as from nPLBs treated with the same partial incisions. The findings of this study showed that culturing PLBs in dark conditions suppresses shoot formation that might interfere with PLB proliferation, and that a large number of secondary PLBs could be obtained from these ePLBs compared with nPLBs after exposure to high light intensity.

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We compared anthocyanidin composition patterns and the expression of anthocyanin biosynthesis genes in Rhododendron kiusianum, R. kaempferi, and their natural hybrids from the Kirishima mountain mass. Compared with the habitat, phenotypic characteristics including tree height and flower color did not change in the transplanted individuals after cutting propagation. According to flower color measurements, R. kiusianum and R. kaempferi belonged to purple and red series, respectively, and their natural hybrids belonged to either the red or purple series. HPLC analysis showed that the petals of most R. kiusianum and natural hybrids contained both cyanidin and delphinidin series pigments, while the petals of R. kaempferi contained only cyanidin series pigments. However, one R. kiusianum individual in the purple series contained only cyanidin series pigments and one natural hybrid individual in the red series contained both cyanidin and delphinidin series pigments. These individuals were thought to be influenced by co-pigmentation or a lack thereof, respectively. All samples expressed F3′H, DFR, and ANS genes in real-time quantitative RT-PCR, and the F3′5′H gene was always expressed in samples containing delphinidin series pigments. These results suggest that the expression of F3′5′H is essential for R. kiusianun and its natural hybrids to produce delphinidin series pigments. This study showed that interspecific hybridization between wild species with purple series flowers and wild species with red series flowers varied the pigment composition and anthocyanin biosynthesis-related gene expression in the natural hybrids, suggesting that it caused the flower color variation in the wild populations in the Kirishima mountains.

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In Japan, there are many genetic resources for breeding hydrangea cultivars, but it is difficult to utilize them effectively for breeding because of a lack of phylogenetic information. In this study, the phylogenetic relationship of H. macrophylla (Thunb.) Ser. f. normalis (E.H.Wilson) H.Hara and H. serrata (Thunb.) Ser. was evaluated by using RAPD markers and sequences of the plastid genes rbcL and matK. The materials were collected from their wild populations throughout Japan. Both RAPD analysis and chloroplast DNA analysis indicated that the genetic diversity of H. serrata var. serrata was higher than that of H. macrophylla f. normalis or that of H. serrata (Thunb.) Ser. var. yesoensis (Koidz.) H.Ohba. These analyses revealed that H. serrata var. serrata of Japan was separated into two groups; i.e., eastern serrata group and western serrata group. The western serrata group was divided into two or three subgroups by single base substitutions in the matK or rbcL fragment sequences. The results of chloroplast DNA analysis indicated that H. serrata of Shikoku, which was one of the western serrata subgroups, was evolutionarily differentiated from other western serrata subgroups. MatK and rbcL sequences of the eastern serrata group were identical to those of H. macrophylla f. normalis and H. serrata var. yesoensis. The matK sequences of the eastern serrata group, H. macrophylla f. normalis and H. serrata var. yesoensis, contained a duplication of 6 bp (GGTTAT), which was not found in the western serrata group or other Hydrangea species. Analysis of the matK and rbcL sequences revealed that H. serrata var. serrata is paraphyletic and that the eastern serrata group, H. macrophylla f. normalis and H. serrata var. yesoensis, form a monophyletic group. The present study provided useful information for breeding hydrangea cultivars and for the taxonomic treatment of H. macrophylla and H. serrata including the varieties.

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The MADS-box gene family is one of the largest transcription factor gene families in plants and is necessary at various developmental stages. Many studies on flower development show that especially MIKC^c-type MADS-box genes are essential for proper floral organ development. We identified and characterized MIKC^c-type MADS-box genes expressed in Eustoma grandiflorum flowers. Twenty-three genes were identified and grouped into 10 clades, which were characterized by conserved specific motifs. Phylogenetic analysis indicated the diversification of AG/PLE, AP3/DEF, PI/GLO, and SEP clades and the occurrence of recent gene duplication events. The floral organ-specific expression patterns were partly diversified within the gene members of AP3/DEF and SEP clades, while they were conserved in AG/PLE and PI/GLO clades. These results suggest that genes with conserved expression as well as those with diversified expression contribute to specifying floral organ identity in E. grandiflorum.

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