Distinct associations between gratitude, self-esteem, and optimism with subjective and psychological well-being among Japanese individuals.

BACKGROUND: Mounting evidence suggests that the effectiveness of positive psychology interventions is influenced by a variety of factors, including cultural context. Identifying intervention targets that can effectively contribute to improving individual well-being under these boundary conditions is a crucial step when developing viable interventions. To this end, we examined how gratitude disposition, self-esteem, and optimism relate to the subjective well-being (SWB) and psychological well-being (PWB) of Japanese individuals. METHODS: Multivariate regression analysis was employed to quantify the unique relationships between the three potential intervention targets and both SWB and PWB, while accounting for the influence of other variables. Participants (N = 71) also engaged in a 4-week experience sampling study to explore how gratitude, self-esteem and optimism shape the link between momentary affective states in everyday life and evaluations of day satisfaction. RESULTS: Multivariate regression analysis revealed that self-esteem was predominantly more strongly associated with SWB compared to gratitude disposition, whereas gratitude disposition was more strongly associated with the PWB dimensions, particularly personal growth, positive relations with others and purpose in life. Experience sampling data indicated that while both gratitude disposition and self-esteem moderated the association between momentary positive affect and day satisfaction evaluations, they did so in opposite ways; greater gratitude disposition strengthened the association, while greater self-esteem weakened it. CONCLUSIONS: Overall, the current results suggest that while gratitude, self-esteem, and optimism influence individual well-being as a whole, they likely play distinct roles in facilitating SWB and PWB in the studied cohort.

Duration of mood effects following a Japanese version of the mood induction task.

Researchers have employed a variety of methodologies to induce positive and negative mood states in study participants to investigate the influence that mood has on psychological, physiological, and cognitive processes both in health and illness. Here, we investigated the effectiveness and the duration of mood effects following the mood induction task (MIT), a protocol that combines mood-inducing sentences, auditory stimuli, and autobiographical memory recall in a cohort of healthy Japanese adult individuals. In Study 1, we translated and augmented the mood-inducing sentences originally proposed by Velten in 1968 and verified that people perceived the translations as being largely congruent with the valence of the original sentences. In Study 2, we developed a Japanese version of the mood induction task (J-MIT) and examined its effectiveness using an online implementation. Results based on data collected immediately after induction showed that the J-MIT was able to modulate the mood in the intended direction. However, mood effects were not observed during the subsequent performance of a cognitive task, the Tower of London task, suggesting that the effects did not persist long enough. Overall, the current results show that mood induction procedures such as the J-MIT can alter the mood of study participants in the short term; however, at the same time, they highlight the need to further examine how mood effects evolve and persist through time to better understand how mood induction protocols can be used to study affective processes more effectively.

Efficient virus-induced gene silencing system in pumpkin (Cucurbita maxima) using apple latent spherical virus vector.

Crude-sap of apple latent spherical virus (ALSV)-infected Chenopodium quinoa leaves was rub-inoculated on the expanded cotyledons of various Cucurbitaceae plants. Most of the species were systemically infected with the virus without obvious symptoms, except pumpkin (Cucurbita maxima). In pumpkin, the ALSV infection was restricted to inoculated cotyledons; it did not spread to the upper true leaves. In situ hybridization showed that the ALSV was confined to part of the cotyledon tissues and it did not invade the phloem tissue, when inoculated at the expanded cotyledon stage. However, when total RNAs from ALSV-infected C. quinoa leaves were inoculated into the cotyledons immediately after germination (folded cotyledon stage) using particle bombardment, ALSV efficiently caused systemic infection. Systemic infection of pumpkin seedlings occurred only when the cotyledons were inoculated within a few days after germination. No systemic infection was observed in the seedlings 4 days after germination. In the grafting test, ALSV was not transmitted from the infected rootstocks to the healthy scions of pumpkins. An efficient virus-induced gene silencing system for pumpkins was established, in which infection with ALSV vectors harboring the phytoene desaturase or sulfur gene fragments resulted in a uniform phenotype in the true leaves of pumpkin seedlings.

Assessing changes in mood state in university students following short-term study abroad.

Short-term study-abroad (STSA) programs provide a more accessible alternative for students who would otherwise not consider engaging in academic activities overseas. Though improvements in the levels of intercultural sensitivity and general academic aspects attained by STSA programs have been previously examined, much less is known regarding the impact such programs have in the mood of students. Here, we examined changes in mood state associated with participation in an STSA program in a group of Japanese university students. Mood states were assessed using the Profile of Mood States (POMS), the Satisfaction With Life Scale (SWLS), and the Gratitude Questionnaire (GQ-6). Results indicated that the POMS mean scores of Vigor-Activity and SWLS peaked at the time immediately following participation in the STSA program; moreover, the same scores were found to be at comparable levels even one month after the end of the program. These results indicate that participation in STSA programs can positively influence the mood state of university students, suggesting that the benefits associated with participation in such programs extend beyond typically reported improvements in the academic domain.

Enhanced academic motivation in university students following a 2-week online gratitude journal intervention.

BACKGROUND: Past studies have associated gratitude interventions with a host of positive outcomes. However, there is a dearth of research regarding the impact such interventions have on the academic motivation of university students, thought to be a primary determinant of academic achievement and overall satisfaction with school activities. Here, we examined the effects of a 2-week online gratitude journal intervention on the academic motivation of university students. METHODS: Eighty-four students were randomly assigned to either an active manipulation group (gratitude group) or a neutral control group. In the first 6 days of each week, participants in the gratitude group were asked to log in to the online system once a day and list up to five things they had felt grateful for. They were also requested to evaluate various aspects of their daily lives. Participants in the control group were only requested to perform the daily self-evaluations. Academic motivation was assessed using the Academic Motivation Scale (AMS), which conceptualizes motivation in academic settings as being composed by three different components, i.e., intrinsic motivation, extrinsic motivation and amotivation, the latter being associated with the perceived lack of contingency between actions and outcomes. Responses were collected 5 times: before group assignment (baseline), 1 week after the start of the intervention, immediately after the intervention, and at two follow-ups, 1 and 3 months after the intervention. RESULTS: Analysis using a self-determination index derived from the AMS components showed that participants who regularly engaged with the gratitude journal task displayed significant enhancements in academic motivation. Additional analysis revealed that the enhancements were driven by decreases in the levels of amotivation. Furthermore, follow-up data showed that there were no signs that such enhancements had receded 3 months after the end of the intervention. Improvements in academic motivation were not observed among participants in the control group. CONCLUSIONS: The current results provide evidence that gratitude interventions can positively impact the academic motivation of university students. More broadly, they show that the effects extend well beyond the realm of typically assessed measures of individual well-being, and can effectively regulate a fundamental component of goal-directed behavior such as motivation.

Apple Russet Ring and Apple Green Crinkle Diseases: Fulfillment of Koch's Postulates by Virome Analysis, Amplification of Full-Length cDNA of Viral Genomes, in vitro Transcription of Infectious Viral RNAs, and Reproduction of Symptoms on Fruits of Apple Trees Inoculated With Viral RNAs.

Apple russet ring and apple green crinkle are graft-transmitted diseases first reported more than 60 years ago, but at present, no association between a specific virus (variant) and the disease has been clearly demonstrated. In this study, we conducted the following series of experiments to identify the causal viruses (variants) of these apple diseases; (1) comprehensive analysis by next-generation sequencing of all viruses in each apple tree affected with russet ring or green crinkle disease, (2) amplification of full-length genomic cDNA of viruses using primers containing the T3 promoter and the in vitro transcription of infectious viral RNAs, (3) inoculation of viral RNA transcripts to both herbaceous and apple plants, (4) analysis of sequence variants of viruses present in infected plants, (5) back-inoculation of sequence variants of candidate viruses to apple seedlings combined with the virus-induced flowering technology using the apple latent spherical virus vector to reproduce the symptom on the fruit as soon as possible, and (6) reproduction of symptoms on the fruits of apple trees inoculated with sequence variants and the re-isolation of each virus variant from apples showing fruit symptoms. The results showed that one of the sequence variants of the apple chlorotic leaf spot virus causes a characteristic ring-shaped rust on the fruits of infected apple trees and that a sequence variant of the apple stem pitting virus probably causes green crinkle symptoms on an infected apple fruit. Thus, we were able to fulfill Koch's postulates to prove the viral etiology of both the apple russet ring and green crinkle diseases. We also propose an experimental system that can prove whether a virus found in diseased tissues is the pathogen responsible for the diseases when the etiology is undetermined.

Virus-Induced Flowering by Apple Latent Spherical Virus Vector: Effective Use to Accelerate Breeding of Grapevine.

Apple latent spherical virus (ALSV) was successfully used in promoting flowering (virus-induced flowering, VIF) in apple and pear seedlings. In this paper, we report the use of ALSV vectors for VIF in seedlings and in vitro cultures of grapevine. After adjusting experimental conditions for biolistic inoculation of virus RNA, ALSV efficiently infected not only progeny seedlings of Vitis spp. 'Koshu,' but also in vitro cultures of V. vinifera 'Neo Muscat' without inducing viral symptoms. The grapevine seedlings and in vitro cultures inoculated with an ALSV vector expressing the 'florigen' gene (Arabidopsis Flowering locus T, AtFT) started to set floral buds 20-30 days after inoculation. This VIF technology was successfully used to promote flowering and produce grapes with viable seeds in in vitro cultures of F1 hybrids from crosses between V. ficifolia and V. vinifera and made it possible to analyze the quality of fruits within a year after germination. High-temperature (37 °C) treatment of ALSV-infected grapevine disabled virus movement to newly growing tissue to obtain ALSV-free shoots. Thus, the VIF using ALSV vectors can be used to shorten the generation time of grapevine seedlings and accelerate breeding of grapevines with desired traits.

Virus-induced gene silencing in chili pepper by apple latent spherical virus vector.

Apple latent spherical virus (ALSV) can infect a variety of crops, usually without inducing symptoms. Partial gene sequences can be introduced into ALSV vectors for the induction of virus-induced gene silencing (VIGS). These features are beneficial for the estimation of gene functions in plants, with relatively concise experimental manipulations. Given that the infectability of chili peppers (Capsicum spp.) by ALSV was unknown, an ALSV infectivity test was performed on the highly pungent Capsicum chinense cultivar 'Habanero'. The chili pepper plants were not infected after rub-inoculation with a crude homogenate of ALSV-infected Chenopodium quinoa leaves, whereas inoculating them with a concentrated ALSV virus preparation caused an infection. Inoculation with an ALSV RNA preparation by gold particle bombardment resulted in high infection rates (about 90%). The infection was systemic and the infected plants were symptomless. For the induction of VIGS, 201-nucleotide fragments of the putative aminotransferase (pAMT) gene were introduced into the ALSV vector. These ALSV vectors infected 80-90% of RNA-inoculated chili pepper seedlings. Expression of pAMT-mRNA was repressed in the placenta of immature fruit of infected plants. The silencing of pAMT in the infected plants caused a substantial decrease in capsaicin content and a concomitant moderate accumulation of the non-pungent bioactive metabolite capsiate in these plants. These results showed that ALSV could be used to study gene functions by VIGS and to enhance capsiate accumulation in chili pepper through genetic modification.

RNA Silencing-Mediated Apple Latent Spherical Virus Vaccine in Plants.

The apple latent spherical virus (ALSV), originally isolated from an apple tree in Japan, is a small spherical virus with a diameter of 25 nm and comprises a bisegmented, single-stranded RNA genome (RNA1 and RNA2) and three different capsid proteins (Vp25, Vp20, and Vp24). The virus can experimentally infect a broad range of plants including, not only model plants (Arabidopsis thaliana and Nicotiana species) but also economically important crops such as cucumber, soybean, tomato, fruit trees, and flowers. ALSV has been used as an effective plant virus vector for virus-induced gene silencing (VIGS) to assess gene functions because the virus infects most of the host plants without showing any symptoms and induces a uniform knockout phenotype in infected plants. Moreover, the VIGS persists throughout plant growth in infected plants. Here, we show that genetically engineered ALSV vectors (ALSV vaccines) containing a partial genome sequence of pathogenic viruses display a high degree of cross-protection against the challenge inoculation of the corresponding pathogenic viruses. Treatment effects can also be expected in virus-infected plants by subsequent inoculation with ALSV vaccine.

Functional divergence between soybean FLOWERING LOCUS T orthologues FT2a and FT5a in post-flowering stem growth.

Genes in the FLOWERING LOCUS T (FT) family integrate external and internal signals to control various aspects of plant development. In soybean (Glycine max), FT2a and FT5a play a major role in floral induction, but their roles in post-flowering reproductive development remain undetermined. Ectopic overexpression analyses revealed that FT2a and FT5a similarly induced flowering, but FT5a was markedly more effective than FT2a for the post-flowering termination of stem growth. The down-regulation of Dt1, a soybean orthologue of Arabidopsis TERMINAL FLOWER1, in shoot apices in early growing stages of FT5a-overexpressing plants was concomitant with highly up-regulated expression of APETALA1 orthologues. The Dt2 gene, a repressor of Dt1, was up-regulated similarly by the overexpression of FT2a and FT5a, suggesting that it was not involved in the control of stem termination by FT5a. In addition to the previously reported interaction with FDL19, a homologue of the Arabidopsis bZIP protein FD, both FT2a and FT5a interacted with FDL12, but only FT5a interacted with FDL06. Our results suggest that FT2a and FT5a have different functions in the control of post-flowering stem growth. A specific interaction of FT5a with FDL06 may play a key role in determining post-flowering stem growth in soybean.

Development of the VIGS System in the Dioecious Plant Silene latifolia.

(1) Background: Silene latifolia is a dioecious plant, whose sex is determined by XY-type sex chromosomes. Microbotryum lychnidis-dioicae is a smut fungus that infects S. latifolia plants and causes masculinization in female flowers, as if Microbotryum were acting as a sex-determining gene. Recent large-scale sequencing efforts have promised to provide candidate genes that are involved in the sex determination machinery in plants. These candidate genes are to be analyzed for functional characterization. A virus vector can be a tool for functional gene analyses; (2) Methods: To develop a viral vector system in S. latifolia plants, we selected Apple latent spherical virus (ALSV) as an appropriate virus vector that has a wide host range; (3) Results: Following the optimization of the ALSV inoculation method, S. latifolia plants were infected with ALSV at high rates in the upper leaves. In situ hybridization analysis revealed that ALSV can migrate into the flower meristems in S. latifolia plants. Successful VIGS (virus-induced gene silencing) in S. latifolia plants was demonstrated with knockdown of the phytoene desaturase gene. Finally, the developed method was applied to floral organ genes to evaluate its usability in flowers; (4) Conclusion: The developed system enables functional gene analyses in S. latifolia plants, which can unveil gene functions and networks of S. latifolia plants, such as the mechanisms of sex determination and fungal-induced masculinization.

Virus-induced gene silencing and virus-induced flowering in strawberry (Fragaria × ananassa) using apple latent spherical virus vectors.

Apple latent spherical virus (ALSV) vector is a convenient alternative to genetic transformation in horticultural plants, especially in species recalcitrant to genetic transformation. ALSV, an RNA virus, can infect a wide variety of plant species including major horticultural plants without inducing symptoms. Here, methodologies were developed for infection of ALSV vectors to strawberry seedlings and plantlets cultured in vitro. A seed-propagated F1 hybrid strawberry cultivar 'Yotsuboshi' was aseptically grown on half-strength Murashige-Skoog medium for 1 month and true leaves were inoculated with an ALSV RNA preparation by particle bombardment. ALSV vector infection rates varied from 58 to 100% according to the insertion sequences, in 'Yotsuboshi' seedlings. Plantlets ('Dover') propagated in vitro could also be infected with ALSV vector at a similar infection rate. For virus-induced gene silencing (VIGS), we prepared an ALSV vector carrying a 201 nucleotide segment of the strawberry phytoene desaturase gene. 'Yotsuboshi' and 'Dover' plants infected by this vector generated completely white leaves at fifth or sixth true leaves and above. For virus-induced flowering (VIF), we used an ALSV vector expressing the Arabidopsis thaliana flowering locus T gene. Strawberry seedlings infected by this vector started to flower from about 2 months post inoculation and bore fruits with viable seeds. The ALSV vector was no longer detected in any of the seedlings from early-flowered strawberries. Thus, the ALSV vector may be beneficial for examination of gene functions by VIGS in strawberry, and VIF using ALSV vector constitutes an effective new plant breeding technique for the promotion of cross-breeding in strawberry.

Gentian (Gentiana triflora) prevents transmission of apple latent spherical virus (ALSV) vector to progeny seeds.

MAIN CONCLUSION: Gentian plants ( Gentiana triflora ) severely restrict apple latent spherical virus (ALSV) invasion to the gametes (pollens and ovules) and block seed transmission to progeny plants. Early flowering of horticultural plants can be induced by infection of ALSV vector expressing Flowering Locus T (FT) gene. In the present study, flowering of gentian plants was induced by infection with an ALSV vector expressing a gentian FT gene and the patterns of seed transmission of ALSV in gentian were compared with those in apple and Nicotiana benthamiana. Infection of gentian progeny plants with ALSV was examined by quantitative reverse transcription-polymerase chain reaction (qRT-PCR), reverse transcription-loop-mediated isothermal amplification (RT-LAMP), and enzyme-linked immunosorbent assay (ELISA). ALSV was not transmitted to the progeny gentian plants, whereas small proportions of apple and N. benthamiana progeny plants are infected with ALSV. The in situ hybridization analyses indicated that ALSVs are not present in gentian pollen and ovules, but detected in most of gametes in apple and N. benthamiana. Collectively, these results suggest that seed transmission of ALSV is blocked in gentian plants through the unknown barriers present in their gametes. On the other hand, apple and N. benthamiana seem to minimize ALSV seed transmission by inhibiting viral propagation in embryos.

The effect of mood state on visual search times for detecting a target in noise: An application of smartphone technology.

The study of visual perception has largely been completed without regard to the influence that an individual's emotional status may have on their performance in visual tasks. However, there is a growing body of evidence to suggest that mood may affect not only creative abilities and interpersonal skills but also the capacity to perform low-level cognitive tasks. Here, we sought to determine whether rudimentary visual search processes are similarly affected by emotion. Specifically, we examined whether an individual's perceived happiness level affects their ability to detect a target in noise. To do so, we employed pop-out and serial visual search paradigms, implemented using a novel smartphone application that allowed search times and self-rated levels of happiness to be recorded throughout each twenty-four-hour period for two weeks. This experience sampling protocol circumvented the need to alter mood artificially with laboratory-based induction methods. Using our smartphone application, we were able to replicate the classic visual search findings, whereby pop-out search times remained largely unaffected by the number of distractors whereas serial search times increased with increasing number of distractors. While pop-out search times were unaffected by happiness level, serial search times with the maximum numbers of distractors (n = 30) were significantly faster for high happiness levels than low happiness levels (p = 0.02). Our results demonstrate the utility of smartphone applications in assessing ecologically valid measures of human visual performance. We discuss the significance of our findings for the assessment of basic visual functions using search time measures, and for our ability to search effectively for targets in real world settings.

Virus-induced down-regulation of GmERA1A and GmERA1B genes enhances the stomatal response to abscisic acid and drought resistance in soybean.

Drought is a major threat to global soybean production. The limited transformation potential and polyploid nature of soybean have hindered functional analysis of soybean genes. Previous research has implicated farnesylation in the plant's response to abscisic acid (ABA) and drought tolerance. We therefore used virus-induced gene silencing (VIGS) to evaluate farnesyltransferase genes, GmERA1A and GmERA1B (Glycine max Enhanced Response to ABA1-A and -B), as potential targets for increasing drought resistance in soybean. Apple latent spherical virus (ALSV)-mediated GmERA1-down-regulated soybean leaves displayed an enhanced stomatal response to ABA and reduced water loss and wilting under dehydration conditions, suggesting that GmERA1A and GmERA1B negatively regulate ABA signaling in soybean guard cells. The findings provide evidence that the ALSV-VIGS system, which bypasses the need to generate transgenic plants, is a useful tool for analyzing gene function using only a single down-regulated leaf. Thus, the ALSV-VIGS system could constitute part of a next-generation molecular breeding pipeline to accelerate drought resistance breeding in soybean.

Identification and functional analysis of SVP ortholog in herbaceous perennial plant Gentiana triflora: Implication for its multifunctional roles.

Information concerning to regulation of vegetative phase and floral initiation in herbaceous perennial plants has been limited to a few plant species. To know and compare flowering regulation in a wider range of plant species, we identified and characterized SHORT VEGETATIVE PHASE (SVP)-like genes (GtSVP-L1 and GtSVP-L2) from herbaceous perennial gentian (Gentiana triflora). Apple latent spherical virus (ALSV)-mediated silencing of the GtSVP-L1 in G. triflora seedlings resulted in early flowering and shortened vegetative phase by about one-third period of time, without vernalization. This indicated that GtSVP-L1 acts as a negative regulator of flowering and vegetative phase. Seasonal change in the expression of GtSVP was monitored in the overwinter buds (OWBs) of G. triflora. It was found that the levels of GtSVP-L1 mRNA in OWBs increased concomitantly with induction and/or maintenance of dormancy, then decreased toward release from dormancy, while that of GtSVP-L2 mRNA remained low and unchanged. These results implied that, in herbaceous perennial plants, SVP ortholog might concern to activity-dormancy control, as well as negative regulation in flowering. Practically, these results can be applicable to non-time-consuming technologies for breeding.

Apple latent spherical virus vector-induced flowering for shortening the juvenile phase in Japanese gentian and lisianthus plants.

MAIN CONCLUSION: Infection by apple latent spherical virus (ALSV) vectors that promote the expression of Arabidopsis thaliana FLOWERING LOCUS T ( AtFT ) or Gentiana triflora GtFT s accelerates flowering in gentian and lisianthus plants. Apple latent spherical virus (ALSV) has isometric virus particles (25 nm in diameter) that contain two ssRNA species (RNA1 and RNA2) and three capsid proteins (Vp25, Vp20, and Vp24). ALSV vectors are used for foreign gene expression and virus-induced gene silencing in a broad range of plant species. Here, we report the infection by ALSV vectors that express FLOWERING LOCUS T (AtFT) from Arabidopsis thaliana or its homolog GtFT1 from Gentiana triflora in three gentian cultivars ('Iwate Yume Aoi' [early flowering], 'Iwate' [medium flowering], and 'Alta' [late flowering]), and two lisianthus cultivars ('Newlination Pink ver. 2' and 'Torukogikyou daburu mikkusu') promotes flowering within 90 days post-inoculation using particle bombardment. Additionally, seedlings from the progeny of the early-flowering plants were tested by tissue blot hybridization, and the results showed that ALSV was not transmitted to the next generation. The promotion of flowering in the family Gentianaceae by ALSV vectors shortened the juvenile phase from 1-3 years to 3-5 months, and thus, it could be considered as a new plant breeding technique in ornamental gentian and lisianthus plants.

Allelic variants of the esterase gene W14/15 differentially regulate overwinter survival in perennial gentian (Gentiana L.).

Overwinter survival has to be under critical regulation in the lifecycle of herbaceous perennial plants. Gentians (Gentiana L.) maintain their perennial life style through producing dormant and freezing-tolerant overwinter buds (OWBs) to overcome cold winter. However, the mechanism acting on such an overwinter survival and the genes/proteins contributing to it have been poorly understood. Previously, we identified an OWB-enriched protein W14/15, a member of a group of α/ß hydrolase fold superfamily that is implicated in regulation of hormonal action in plants. The W14/15 gene has more than ten variant types in Gentiana species. However, roles of the W14/15 gene in OWB survival and functional difference among those variants have been unclear. In the present study, we examined whether the W14/15 gene variants are involved in the mechanism acting on overwinter survival, by crossing experiments using cultivars carrying different W14/15 variant alleles and virus-induced gene silencing experiments. We found that particular types of the W14/15 variants (W15a types) contributed toward obtaining high ability of overwinter survival, while other types (W14b types) did not, or even interfered with the former type gene. This study demonstrates two findings; first, contribution of esterase genes to winter hardiness, and second, paired set or paired partner among the allelic variants determines the ability of overwinter survival.

The Soybean-Specific Maturity Gene E1 Family of Floral Repressors Controls Night-Break Responses through Down-Regulation of FLOWERING LOCUS T Orthologs.

Photoperiodism is a rhythmic change of sensitivity to light, which helps plants to adjust flowering time according to seasonal changes in daylength and to adapt to growing conditions at various latitudes. To reveal the molecular basis of photoperiodism in soybean (Glycine max), a facultative short-day plant, we analyzed the transcriptional profiles of the maturity gene E1 family and two FLOWERING LOCUS T (FT) orthologs (FT2a and FT5a). E1, a repressor for FT2a and FT5a, and its two homologs, E1-like-a (E1La) and E1Lb, exhibited two peaks of expression in long days. Using two different approaches (experiments with transition between light and dark phases and night-break experiments), we revealed that the E1 family genes were expressed only during light periods and that their induction after dawn in long days required a period of light before dusk the previous day. In the cultivar Toyomusume, which lacks the E1 gene, virus-induced silencing of E1La and E1Lb up-regulated the expression of FT2a and FT5a and led to early flowering. Therefore, E1, E1La, and E1Lb function similarly in flowering. Regulation of E1 and E1L expression by light was under the control of E3 and E4, which encode phytochrome A proteins. Our data suggest that phytochrome A-mediated transcriptional induction of E1 and its homologs by light plays a critical role in photoperiodic induction of flowering in soybean.

Isolation and characterization of the C-class MADS-box gene involved in the formation of double flowers in Japanese gentian.

BACKGROUND: Generally, double-flowered varieties are more attractive than single-flowered varieties in ornamental plants. Japanese gentian is one of the most popular floricultural plants in Japan, and it is desirable to breed elite double-flowered cultivars. In this study, we attempted to characterize a doubled-flower mutant of Japanese gentian. To identify the gene that causes the double-flowered phenotype in Japanese gentian, we isolated and characterized MADS-box genes. RESULTS: Fourteen MADS-box genes were isolated, and two of them were C-class MADS-box genes (GsAG1 and GsAG2). Both GsAG1 and GsAG2 were categorized into the PLE/SHP subgroup, rather than the AG/FAR subgroup. In expression analyses, GsAG1 transcripts were detected in the second to fourth floral whorls, while GsAG2 transcripts were detected in only the inner two whorls. Transgenic Arabidopsis expressing GsAG1 lacked petals and formed carpeloid organs instead of sepals. Compared with a single-flowered gentian cultivar, a double-flowered gentian mutant showed decreased expression of GsAG1 but unchanged expression of GsAG2. An analysis of the genomic structure of GsAG1 revealed that the gene had nine exons and eight introns, and that a 5,150-bp additional sequence was inserted into the sixth intron of GsAG1 in the double-flowered mutant. This insert had typical features of a Ty3/gypsy-type LTR-retrotransposon, and was designated as Tgs1. Virus-induced gene silencing of GsAG1 by the Apple latent spherical virus vector resulted in the conversion of the stamen to petaloid organs in early flowering transgenic gentian plants expressing an Arabidopsis FT gene. CONCLUSIONS: These results revealed that GsAG1 plays a key role as a C-functional gene in stamen organ identity. The identification of the gene responsible for the double-flowered phenotype will be useful in further research on the floral morphogenesis of Japanese gentian.