Faculty Profiles - MIYAZAKI Yuko

Papers - MIYAZAKI Yuko

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Does a coexisting congener of a mixed mating species affect the genetic structure and selfing rate via reproductive interference? Reviewed

Koki R. Katsuhara, Atushi Ushimaru, Yuko Miyazaki

Oecologia 2024.8

Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

Abstract

Reproductive interference is defined as an interspecific interaction that reduces fitness via mating processes. Although its ecological and evolutionary consequences have attracted much attention, how reproductive interference affects the population genetic structures of interacting species is still unclear. In flowering plants, recent studies found that self-pollination can mitigate the negative effects of reproductive interference. Selfing-biased seed production is expected to increase population-level inbreeding and the selfing rate, and limits gene flow via pollinator outcrossing among populations. We examined the population genetics of the mixed-mating annual herb Commelina communis f. ciliata, focusing on reproductive interference by the sympatric competing congener C. communis using microsatellite markers. First, we found that almost all C. c. f. ciliata populations had relatively high inbreeding coefficients. Then, comparing sympatric and allopatric populations, we found evidence that reproductive interference from a competing congener increased the inbreeding coefficient and selfing rate. Allopatric populations exhibit varied selfing rates while almost all sympatric populations exhibit extremely high selfing rates, suggesting that population selfing rates were also influenced by unexamined factors, such as pollinator limitation. Besides, our findings revealed that reproductive interference from a competing congener did not limit gene flow among populations. We present the first report on how reproductive interference affects the genetic aspects of populations. Our results suggested that the high selfing rate of C. c. f. ciliata promotes its sympatric distribution with C. communis, even in the presence of reproductive interference, although it is not clear whether reproductive interference directly causes the high selfing rate.

DOI： 10.1007/s00442-024-05607-x

Other Link： https://link.springer.com/article/10.1007/s00442-024-05607-x/fulltext.html

Pollinators of Arisaema nambae (Araceae), endemic to Okayama and Hiroshima prefectures, western Japan Reviewed

Tetsuta Kubo, Tetsuya K. Matsumoto, Yuko Miyazaki, Okihito Yano

Journal of Asia-Pacific Biodiversity 17 ( 1 ) 191 - 195 2024.3

A malformation of sex-changing plant Arisaema serratum (Araceae) produces both male and female inflorescences Reviewed

Tetsuya K. Matsumoto, Ryohei Fujisato, Munetaka Sugiyama, Yuko Miyazaki, Jin Murata

BOTANY LETTERS 171 102 - 108 2024.2

Language：English Publishing type：Research paper (scientific journal) Publisher：TAYLOR & FRANCIS LTD

The genus Arisaema (Araceae) can change sex expression between male and female with increasing plant size (sequential hermaphrodism). As most Arisaema species have only one inflorescence on each individual, sex expression is seemingly determined at the individual level. However, malformations with male and female inflorescences have occasionally been observed. Unfortunately, their developmental origin is unclear because of a lack of detailed descriptions of the shoot structure. To estimate the unit of sex determination in Arisaema, we observed the morphology of an aberrant individual of Arisaema serratum (Thunberg) Schott with multiple inflorescences for three years. In the second year, the aberrant individual produced pure male and female inflorescences. Based on the phyllotactic pattern of this malformation, we estimated that the inflorescences were duplicated due to a broadening of the apical meristem via fasciation. Contrary to other Arisaema plants with multiple inflorescences reported previously, the corm of the aberrant individual did not subdivide nor branch spontaneously after the growing season for three years. Thus, duplicated inflorescences presumably shared the resource supply without physiological partitioning during sex determination. These results imply that sex expression is determined at the inflorescence level but not at the individual or floret levels in dioecious Arisaema.

DOI： 10.1080/23818107.2023.2234973

Two closely related species of the Arisaema ovale group (Araceae) selectively attract male fungus gnats of different Anatella species (Diptera: Mycetophilidae) Reviewed

Tetsuya K. Matsumoto, Masahiro Sueyoshi, Shigetaka Sakata, Yuko Miyazaki, Muneto Hirobe

Plant Systematics and Evolution 309 4 2023.1

Gall midge pollination and ant-mediated fruit dispersal of Pinellia tripartita (Araceae) Reviewed

Tetsuya K. Matsumoto, Motoya Onoue, Takashi Miyake, Kentaro Ohnishi, Kiyoto Takazoe, Muneto Hirobe, Yuko Miyazaki

Plant Ecology 2022.12

Evaluating the soil microbe community‐level physiological profile using <scp>EcoPlate</scp> and soil properties at 33 forest sites across Japan Reviewed

Masahiro Nakamura, Chisato Terada, Kinya Ito, Kazuaki Matsui, Shigeru Niwa, Masae Ishihara, Tanaka Kenta, Tetsuro Yoshikawa, Taku Kadoya, Tsutom Hiura, Hiroyuki Muraoka, Ken Ishida, Naoki Agetsuma, Ryosuke Nakamura, Hitoshi Sakio, Masahiro Takagi, Akira S. Mori, Megumi K. Kimura, Hiroko Kurokawa, Tsutomu Enoki, Tatsuyuki Seino, Atsushi Takashima, Hajime Kobayashi, Kazuho Matsumoto, Koichi Takahashi, Ryunosuke Tateno, Tomohiro Yoshida, Tatsuro Nakaji, Masayuki Maki, Kazutaka Kobayashi, Karibu Fukuzawa, Kazuhiko Hoshizaki, Kazuhide Ohta, Keito Kobayashi, Motohiro Hasegawa, Satoshi N. Suzuki, Michinori Sakimoto, Yoichiro Kitagawa, Akiko Sakai, Hirofumi Kondo, Tomoaki Ichie, Koji Kageyama, Ayaka Hieno, Shogo Kato, Tatsuya Otani, Yasuhiro Utsumi, Tomonori Kume, Kosuke Homma, Koju Kishimoto, Kazuhiko Masaka, Kenta Watanabe, Motomu Toda, Dai Nagamatsu, Yuko Miyazaki, Tamon Yamashita, Naoko Tokuchi

Ecological Research 37 ( 3 ) 432 - 445 2022.2

Language：English Publishing type：Research paper (scientific journal) Publisher：Wiley

We present the largest freely available EcoPlate dataset for Japan, comprising data collected from a network of 33 natural forest sites (77 plots) in regions of East Asia ranging from cool temperate to subtropical. EcoPlate is a 96-well microplate that contains three repeated sets of 31 response wells with different sole carbon substrates. The utilization of each carbon substrate by the microbial community is quantified by the color density of the well during incubation. EcoPlate can provide a multifunctional index of a soil microbial community. Soil properties (water content, carbon [C] and nitrogen [N] contents, the C/N ratio, and pH) that are essential for interpreting the EcoPlate results were also measured. The network is part of the Forest and Grassland Survey of the Monitoring Sites 1000 Project established by the Ministry of the Environment. Using a standardized protocol, soil was sampled between September and December 2020. A preliminary principal component analysis was performed on the temporal integration of color density using 31 substrates. For the temporal integration, we calculated the cumulative amount of color development by integrating the color density development curve. PC1 contributed 55.6% and is thought to represent the magnitude of the overall absorbance of all substrates. The model of environmental factors including elevation and the model of soil properties, including water content and pH, were selected as the best-fit models for variation in PC1. EcoPlate data enable the meta-analysis of comparative studies among forest types and testing community ecology and ecosystem function hypotheses at broad spatial scales. The complete data set for this abstract published in the Data Paper section of the journal is available in electronic format in MetaCat in JaLTER at http://db.cger.nies.go.jp/JaLTER/metacat/metacat/ERDP-2022-01.1/jalter-en.

DOI： 10.1111/1440-1703.12293

Selective pollination by fungus gnats potentially functions as an alternative reproductive isolation among five Arisaema species. Reviewed International journal

Tetsuya K Matsumoto, Muneto Hirobe, Masahiro Sueyoshi, Yuko Miyazaki

Annals of botany 2020.12

Language：English Publishing type：Research paper (scientific journal)

BACKGROUND AND AIMS: Interspecific difference in pollinators (pollinator isolation) is important for reproductive isolation in flowering plants. Species-specific pollination by fungus gnats has been discovered in several plant taxa, suggesting that they can contribute to reproductive isolation. Nevertheless, their contribution has not been studied in detail, partly because they are too small for field observations during flower visitation. To quantify their flower visitation, we used the genus Arisaema (Araceae) because the pitcher-like spathe of Arisaema can trap all floral visitors. METHODS: We evaluated floral visitor assemblage in an altitudinal gradient including five Arisaema species. We also examined interspecific differences in altitudinal distribution (geographic isolation) and flowering phenology (phenological isolation). To exclude the effect of interspecific differences in altitudinal distribution on floral visitor assemblage, we established 10 experimental plots including the five Arisaema species on high- and low-altitude areas and collected floral visitors. We also collected floral visitors in three additional sites. Finally, we estimated the strength and contribution of these three reproductive barriers using the unified formula for reproductive isolation. KEY RESULTS: Each Arisaema species selectively attracted different fungus gnats in the altitudinal gradient, experimental plots, and additional sites. Altitudinal distribution and flowering phenology differed among the five Arisaema species, whereas the strength of geographic and phenological isolations were distinctly weaker than those in pollinator isolation. Nevertheless, the absolute contribution of pollinator isolation to total reproductive isolation was weaker than geographic and phenological isolations, because pollinator isolation functions after the two early-acting barriers in plant life history. CONCLUSIONS: Our results suggest that selective pollination by fungus gnats potentially contributes to reproductive isolation. Since geographic and phenological isolations can be disrupted by habitat disturbance and interannual climate change, the strong and stable pollinator isolation might compensate for the weakened early-acting barriers as an alternative reproductive isolation among the five Arisaema species.

DOI： 10.1093/aob/mcaa204

Predicting effects of climate change on productivity and persistence of forest trees Reviewed

Russell D. Kramer, H. Roaki Ishii, Kelsey R. Carter, Yuko Miyazaki, Molly A. Cavaleri, Masatake G. Araki, Wakana A. Azuma, Yuta Inoue, Chinatsu Hara

ECOLOGICAL RESEARCH 35 ( 4 ) 562 - 574 2020.7

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY

Global climate change increases uncertainty in sustained functioning of forest ecosystems. Forest canopies are a key link between terrestrial ecosystems, the atmosphere, and climate. Here, we introduce research presented at the 66th meeting of the Ecological Society of Japan in the symposium "Structure and function of forest canopies under climate change." Old-growth forest carbon stores are the largest and may be the most vulnerable to climate change as the balance between sequestration and emission could easily be tipped. Detailed structural analysis of individual large, old trees shows they are allocating wood to the trunk and crown in patterns that cannot be deduced from ground, thus can be used to more accurately quantify total forest carbon and sequestration. Slowly migrating species sensitive to novel climatic conditions will have to acclimate at the individual level. Accounting for physiological responses of trees to climate change will improve predictions of future species distributions and subsequent functioning of forest ecosystems. Field experiments manipulating temperature and precipitation show how trees compensate physiologically to mitigate for higher temperatures and drought. However, it is difficult to measure acclimation responses over long timeframes. Intraindividual trait variation is proposed as an indicator of acclimation potential of trees to future conditions and suggests that acclimation potential may vary among regional populations within a species. Integrating whole-tree structural data with physiological data offers a promising avenue for understanding how trees will respond to climatic shifts.

DOI： 10.1111/1440-1703.12127

Corrigendum: Development of microsatellite markers for the annual andromonoecious herb Commelina communis f. ciliata (Commelinaceae) [Genes Genet. Syst. (2019) 94, p. 133–138]

Koki R. Katsuhara, Naoyuki Nakahama, Taketo Komura, Masaya Kato, Yuko Miyazaki, Yuji Isagi, Motomi Ito, Atushi Ushimaru

Genes & Genetic Systems 95 ( 1 ) 51 - 51 2020.2

Pre-pollination barriers between two sympatric Arisaema species in northern Shikoku Island, Japan Reviewed

Tetsuya K. Matsumoto, Yuko Miyazaki, Masahiro Sueyoshi, Yoshihiro Senda, Kazuhiro Yamada, Muneto Hirobe

AMERICAN JOURNAL OF BOTANY 2019.11

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY

Premise The genus Arisaema (Araceae) has rapidly diversified in Japan, and multiple species often coexist in the field. Although Japanese Arisaema species hybridize from artificial crossing, hybrid individuals are rare in mixed populations; suggesting the presence of effective pre-pollination barriers. We examined the following reproductive barriers between A. sikokianum and A. tosaense: habitat, phenology, and pollinator isolations. Methods Habitat isolation was examined by interspecific comparisons of microhabitat conditions at a mixed site and of altitude at the sampling site of herbarium specimens. Phenological isolation was evaluated by comparing seasonal transition in apparent spathe condition and frequency of insect visitation. Pollinator isolation was examined by comparing floral visitor assemblages between the two Arisaema species. To avoid overestimation of pollinator isolation due to seasonal changes in insect assemblages, we also compared visitor assemblages between natural and late-flowering A. sikokianum, where the latter was experimentally introduced and blooming with a natural A. tosaense population. Results Microhabitat conditions and sampling elevations of herbarium specimens overlapped between the two Arisaema species. At the population level, A. sikokianum and A. tosaense flowered for 39 and 52 days, respectively, with 13 days overlap. Insect visitation in A. sikokianum decreased before the seasonal overlap. Floral visitor assemblages differed between the two Arisaema species, while the difference between natural and late-flowering A. sikokianum was less distinct. Conclusions Phenological and pollinator isolation contribute to reproductive isolation between the two Arisaema species and should enable the two species to coexist in this area.

DOI： 10.1002/ajb2.1389

Development of microsatellite markers for the annual andromonoecious herb Commelina communis f. ciliata (Commelinaceae) Reviewed

Koki R. Katsuhara, Naoyuki Nakahama, Taketo Komura, Masaya Kato, Yuko Miyazaki, Yuji Isagi, Motomi Ito, Atushi Ushimaru

GENES & GENETIC SYSTEMS 94 ( 3 ) 133 - 138 2019.6

Language：English Publishing type：Research paper (scientific journal) Publisher：GENETICS SOC JAPAN

Commelina communis f. ciliata (Commelinaceae), a newly distinguished taxon, is an annual andromonoecious herb exhibiting a mixed mating system, the details of which remain unclear. We developed microsatellite markers for use in exploring the evolution of andromonoecy and mixed mating in the species. Fifteen micro satellite loci were developed using next-generation sequencing. The primer sets were used to evaluate 65 C. communis f. ciliata individuals from three populations in Japan; we found 1-13 alleles per locus and the expected heterozygosity ranged from 0.00 to 0.76. The markers are potentially useful to examine intra- and inter-species genetic structure and the mixed mating strategy of Commelina species via paternity analysis.

DOI： 10.1266/ggs.18-00058

Population structures and spatial patterns of two unpalatable Arisaema species (Araceae) with and without clonal reproduction in riparian forest intensively grazed by Sika deer Reviewed

Matsumoto TK, Hirobe M, Akaji Y, Miyazaki Y

Journal of Forestry Research 2019

The opportunities and challenges of applying tree climbing techniques as a canopy access method in canopy biology Reviewed

Nakanishi Akira, Azuma Wakana, Tanaka Mizue, Miyazaki Yuko, Inui Yoko

JAPANESE JOURNAL OF ECOLOGY 68 ( 2 ) 125 - 139 2018

Language：Japanese Publisher：The Ecological Society of Japan

Canopy biology is the natural science that aimed at understanding of the biodiversity, biological processes, and ecological functions of forest canopies. Canopies determine the structural and energetic properties of forest ecosystems. Since the 1980s, canopy biology has progressed rapidly through the development of methods for accessing treetops. The rope climbing techniques used widely in canopy studies have developed from diverse procedures that allow human access to the top layers of forest vegetation. In comparison with other access hardware, e.g., cranes and gantries, rope assemblies have advantages in terms of user mobility, repeated access, and cost. The availability and safety of tree climbing techniques have improved with recent developments in mountain climbing gear and methodologies for their use. In this review, we use candidate studies to introduce the advantages, prospects and challenges of climbing techniques for tree canopy studies. Tree climbing allows excellent access to treetops in all types of forests, across all geographical locations. We expect further progress through combinations of rope climbing and other access methodologies. In the interests of safety and effectiveness, a platform should be developed for the distribution of relevant information to prospective tree climbing researchers and those who may wish to use the procedures for other activities, such as arboriculture.

DOI： 10.18960/seitai.68.2_125

Other Link： https://agriknowledge.affrc.go.jp/RN/2010922617

Relationship between seasonal progression of floral meristem development and FLOWERING LOCUS T expression in the deciduous tree Fagus crenata Reviewed

Yuko Miyazaki, Akiko Satake

ECOLOGICAL RESEARCH 32 ( 4 ) 627 - 631 2017.7

Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER JAPAN KK

Estimating the timing of flower bud formation in plants is essential to identify environmental factors that regulate floral transition. The presence of winter dormancy between the initiation of flowers and anthesis, characteristic of most trees in the temperate forests, hampers accurate estimation of the timing of floral transition. To overcome this difficulty, expression levels of flowering-time genes could be used as indicators of the timing of floral transition. Here, we evaluated the usefulness of molecular markers in estimating the timing of floral transition in Fagus crenata, a deciduous tree that shows intermittent and synchronized flowering at the population level. We selected FLOWERING LOCUS T (FT) as a candidate molecular marker and quantified the expression levels of its ortholog in F. crenata (FcFT). Subsequently, we analyzed the relationship between morphogenetic changes that occur between the vegetative state of the buds and the initiation of floral organs, and compared the FcFT expression levels in reproductive and vegetative buds, collected from spring to autumn. FcFT expression in leaves peaked at least two weeks before the morphological changes associated with flowering were visible in the buds in late July. FcFT expression levels were significantly higher in the reproductive buds than in the vegetative buds in July. These results suggest that the FcFT expression in July is a reliable indicator of the timing and occurrence of floral transition. This study highlights the utility of molecular tools in unraveling reproductive dynamics in plants, in combination with ecological and physiological approaches.

DOI： 10.1007/s11284-017-1462-3

Survival and growth of Fagus crenata seedlings in relation to biological and microtopographical factors in a cool temperate broadleaf forest Reviewed

Yasuaki Akaji, Muneto Hirobe, Yuko Miyazaki, Takushi Makimoto, Shu Kinoshita, Itsuka Hattori, Keiji Sakamoto

JOURNAL OF FOREST RESEARCH 22 ( 5 ) 294 - 302 2017

Language：English Publishing type：Research paper (scientific journal) Publisher：TAYLOR & FRANCIS LTD

The seedling stage is critical in the life cycle of trees, and performance is controlled by both abiotic and biotic factors, which are spatially heterogeneous. We investigated the relationships between the seedling survival or growth of Fagus crenata and seven potentially influencing factors (culm density of dwarf bamboo, slope angle, topographic convexity, distance from the nearest conspecific adult, and local density of F. crenata seedlings, and seedling size and age), under consideration of the changes in direction and strength of the microtopographic effects across space. In 2011, we identified all F. crenata seedlings (maximum stem length <50cm) within a 90x30-m plot in a cool-temperate forest in western Japan and then recorded their survival and growth of stem length in 2012. The best model based on Akaike's information criterion indicated that the size, age, and distance had positive effects on the survival while slope and convexity had negative effects, and that the strength of the negative effect of convexity varied spatially even within our plot. Meanwhile, the size and culm density had positive and negative effects on the growth, respectively. These results suggest that F. crenata seedlings have more chance to survive at the site on a gentle slope with planar or relatively concave undulations, where the conspecific adults stood apart, and that the seedlings show higher growth rate at the sites without dense dwarf bamboo. Furthermore, we demonstrate that the spatially nonstationary effect of microtopography controls the spatial pattern of seedling survival.

DOI： 10.1080/13416979.2017.1354749

Survival and growth of Fagus crenata seedlings in relation to biological and microtopographical factors in a cool temperate broadleaf forest (vol 22, pg 294, 2017) Reviewed

Y. Akaji, M. Hirobe, Y. Miyazaki, T. Makimoto, S. Kinoshita, Hattori, I, K. Sakamoto

JOURNAL OF FOREST RESEARCH 22 ( 5 ) III - III 2017

Temporal and spatial dynamics of an old-growth beech forest in western Japan Reviewed

Uyanga Ariya, Ken-Ya Hamano, Takushi Makimoto, Shu Kinoshita, Yasuaki Akaji, Yuko Miyazaki, Muneto Hirobe, Keiji Sakamoto

JOURNAL OF FOREST RESEARCH 21 ( 2 ) 73 - 83 2016.4

Language：English Publishing type：Research paper (scientific journal) Publisher：TAYLOR & FRANCIS LTD

Dendrochronological approaches enable us to understand forest stand dynamics by estimation of disturbance history and age structure. The present study was conducted in an old-growth beech forest in a forest reserve in western Japan. Increment cores were taken for tree ring analysis from all canopy trees in a 50 m x 130 m study plot. Radial growth release criteria were developed to identify significant growth releases in each tree ring series and to characterize the disturbance history of the study site. The age structure of the forest was indicative of continuous establishment by Fagus crenata and simultaneous establishment by Magnolia obovata. A variety of low-intensity disturbances were identified in each decade, especially after the 1900s, but the occurrence of high-intensity catastrophic disturbance was rare, and likely played an important role in maintaining species diversity in the existing forest canopy. The results also suggest that F. crenata regenerates gradually before and after both large- and small-scale disturbances, whereas M. obovata and Betula grossa regenerate only after large-scale catastrophic disturbances.

DOI： 10.1007/s10310-015-0514-1

The relationship between seedling survival rates and their genetic relatedness to neighboring conspecific adults Reviewed

Yasuaki Akaji, Yuko Miyazaki, Muneto Hirobe, Takushi Makimoto, Keiji Sakamoto

PLANT ECOLOGY 217 ( 4 ) 465 - 470 2016.4

Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER

Seedling genotype is one of the major factors affecting seedling survival when the rate of damage by natural enemies depends on a host genotype. However, to our knowledge, no previous study has examined the mortality of seedlings adjacent to conspecific adults, considering intraspecific variation in seedling genotypes. On the basis of the assumption that natural enemies adapt to adult trees having a unique genotype, we tested the hypothesis that seedling survival decreases when they are more closely genetically related to neighboring adults, by measuring the mortality rate of seedlings of Fagus crenata growing in a cool-temperate forest in Japan. We estimated the genetic relatedness of seedlings (2 and 6 years old) to the neighboring adult F. crenata using microsatellite analysis and measured seedling survival. We determined that there was a non-significant negative correlation between seedling survival and genetic relatedness in the 2-year-old seedling cohort, and a non-significant but positive correlation in the 6-year-old seedlings. Our results call for further studies on the potential relationship between seedling survival and genetic relatedness to neighboring adults.

DOI： 10.1007/s11258-016-0591-z

Planning a management program for expanding bamboo forests based on scenario analysis Reviewed

Miyazaki Y, Osawa T, Mitsuhashi H

Japanese Journal of Conservation Ecology 20 ( 1 ) 3 - 14 2015

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：The Ecological Society of Japan

To manage the expansion of bamboo forests efficiently, it is necessary to predict where expansion is likely. However, predicting bamboo distribution using statistical models is challenging due to biased distributions, heterogeneous invasion histories, and strong neighbor effects. Furthermore, clonal and invasive species such as bamboo show a non-linear response to environmental factors. Here, we construct a spatial model to predict locations of high penetration probability after controlling for these problems, using data for bamboo distribution in Toyooka, Hyogo Prefecture, Japan. First, we used MaxEnt to reveal the full range of possible bamboo survival and to control for the effects of clonal growth. Second, we constructed a predictive model of invasion using environmental factors. The first model showed that distance from the source patch strongly affected expansion and that constraints from environmental factors were not significant. The final model explained about 70% of actual expansion. Scenario analyses showed that bamboo expansion is best controlled by removing smaller patches. Based on our results, we discuss issues in bamboo forest management and planning.

DOI： 10.18960/hozen.20.1_3

Nitrogen as a key regulator of flowering in Fagus crenata: understanding the physiological mechanism of masting by gene expression analysis Reviewed

Yuko Miyazaki, Yosuke Maruyama, Yukako Chiba, Masaki J. Kobayashi, Benesh Joseph, Kentaro K. Shimizu, Keiichi Mochida, Tsutom Hiura, Hirokazu Kon, Akiko Satake

ECOLOGY LETTERS 17 ( 10 ) 1299 - 1309 2014.10

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-BLACKWELL

The role of resource availability in determining the incidence of masting has been widely studied, but how floral transition and initiation are regulated by the resource level is unclear. We tested the hypothesis that floral transition is stimulated by high resource availabiltiy in Fagus crenata based on a new technique, the expression analyses of flowering genes. We isolated F. crenata orthologues of FLOWERING LOCUS T, LEAFY and APETALA1, and confirmed their functions using transgenic Arabidopsis thaliana. We monitored the gene expression levels for 5 years and detected a cycle of on and off years, which was correlated with fluctuations of the shoot-nitrogen concentration. Nitrogen fertilisation resulted in the significantly higher expression of flowering genes than the control, where all of the fertilised trees flowered, whereas the control did not. Our findings identified nitrogen as a key regulator of mast flowering, thereby providing new empirical evidence to support the resource budget model.

DOI： 10.1111/ele.12338

Dynamics of internal carbon resources during masting behavior in trees Reviewed

Yuko Miyazaki

ECOLOGICAL RESEARCH 28 ( 2 ) 143 - 150 2013.3

Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER JAPAN KK

Several proximate factors of masting have been provided. Here, I focus on the role of internal factors, especially the relationship between internal carbon resources and modular structures in trees. I summarize various studies of carbon resource allocation for reproduction during masting events in terms of the proximate factors of masting and discuss the modular structure in which trees accumulate and consume carbon resources as well as the timing when internal carbon resources affect masting since trees have complex resource dynamics among organs. The resource budget model, which provides a simple mechanistic explanation of the masting mechanism, is supported by various study lines. This model assumes decreasing levels of stored photosynthate after flowering and fruiting. According to several studies, however, carbon reserves do not decrease after fruiting in species in which the modules autonomously allocate current photosynthate for fruiting. In addition, it is important to elucidate when carbon resources affect masting events because during their long developmental processes, trees pass through various stages until they produce maturing fruits to create successful masting events. To explore the mechanisms of masting in future studies, it would be important to figure out how and when candidate factors (including nutrients other than carbon) may influence the entire reproduction process, for example, using field manipulation experiments.

DOI： 10.1007/s11284-011-0892-6

Dwarf bamboos (Sasa pubiculmis Makino subsp. pubiculmis) are not monocarpic plants : evidence from flowering pattern and genetic structure(<Feature>Why bamboos show gregarious flowering habits? -with special reference to the evolutional tren Reviewed

Miyazaki Yuko, Ohnishi Naoki, Hino Takafumi, Hiura Tsutom

JAPANESE JOURNAL OF ECOLOGY 60 ( 1 ) 73 - 79 2010

Language：Japanese Publisher：日本生態学会暫定事務局

ササ類は開花・結実の豊凶がきわめて明瞭であり、加えて生涯で一度のみ繁殖する一回繁殖型植物と考えられてきた。一方、ササ類は個体群の遺伝構造の把握が困難であったため、これまで一回繁殖性について検証されることはなかった。しかしササ類の特異的な繁殖特性を解明するにはまず一回繁殖性の検証が不可欠である。そこで、オモエザサ個体群において遺伝構造を調べると共に、4年間の開花パターンの調査を行い、一回繁殖性の検証を行った。その結果、開花稈は全て同一ジェネットに属し、ジェネットの占有面積は3ha以上に及んだ。しかし、同一ジェネット内の稈が全て開花したのではなく、大別すると、全ての稈が開花していない範囲、開花稈と非開花稈が混在している範囲、全ての稈が開花している範囲がそれぞれ、同一ジェネット内に同時に存在した。全ての稈が開花した範囲のうち、開花後に全ての地上部が枯死した範囲もあったが、翌年以降も稈が生残する範囲もあった。開花後に地上部が枯死した範囲の地下茎からは、翌年以降に新しい稈や花序が再生する現象がみられた。開花が起こる範囲は年毎に変化したが、同一ジェネットに属していても4年間でまだ一度も開花していない範囲も存在した。また、ラメット間の生理的統合を調べるため、炭素安定同位体(<sup>13</sup>C)を用いてトレース実験を行った結果、非開花稈から地下茎で繋がった開花稈へ<sup>13</sup>Cが転流していた。これらのことから、研究対象としたオモエザサは一斉に開花はするものの、必ずしも一回繁殖型の生活史を有していないことが分かった。

DOI： 10.18960/seitai.60.1_73

Resource level as a proximate factor influencing fluctuations in male flower production in Cryptomeria japonica D. Don Reviewed

Yuko Miyazaki, Takeshi Osawa, Yoshiaki Waguchi

JOURNAL OF FOREST RESEARCH 14 ( 6 ) 358 - 364 2009.12

Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER JAPAN KK

Airborne pollen of Cryptomeria japonica causes severe pollinosis, and the number of people suffering from pollinosis has increased rapidly during recent decades. Male flower production in C. japonica shows annual variability; thus, predicting male flower production for the following spring could be a countermeasure against pollinosis. We analyzed factors that explain fluctuations in male flower production of C. japonica according to parameters reflecting internal resource dynamics based on field observations. In addition, we carried out experiments to regulate available resource levels using artificial shading to test the effect of internal resource levels on the number of male flowers produced. We found that temperature and precipitation in the previous summer and a relative increase in male flower production in the previous year were negatively related, whereas sunshine duration in the previous summer and diameter at breast height were positively related to the current year increase in male flower production. The number of male flowers was significantly reduced by the shading treatment and was positively correlated with the amount of total non-structural carbohydrates in the root. These results suggest that understanding the parameters controlling internal resource levels could lead to more accurate predictions of male flower production.

DOI： 10.1007/s10310-009-0148-2

Genets of dwarf bamboo do not die after one flowering event: evidence from genetic structure and flowering pattern Reviewed

Yuko Miyazaki, Naoki Ohnishi, Hino Takafumi, Tsutom Hiura

JOURNAL OF PLANT RESEARCH 122 ( 5 ) 523 - 528 2009.9

Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER TOKYO

Dwarf bamboos in the genus Sasa are believed to be long-lived, synchronously flowering, and monocarpic plants. However, the monocarpy of dwarf bamboo has not been confirmed, because whether all ramets within one genet flower at the same time cannot be determined without differentiating the genetic structure among ramets. This study aims to evaluate the reproductive traits of Sasa pubiculmis by verifying the monocarpy and physiological integration between flowering ramets and non-flowering ramets during a 4-year flowering period. One genotypically identified genet, which covered an area of approximately 3 ha, had both flowering and non-flowering patches of ramets during the 4-year flowering period (2004-2007). A fraction of the flowering genet remained non-flowering during the 4 years of observation, and did not die after mass flowering. Flowering ramets were physically connected to non-flowering ramets via rhizomes, and assimilated (13)C was allocated from non-flowering ramets to flowering ramets. Consequently, we clarified that this dwarf bamboo potentially has polycarpic reproductive traits rather than monocarpic, and a genet can keep rhizomes and non-flowering patches alive to sustain the organism after mass flowering.

DOI： 10.1007/s10265-009-0241-9

Development and characterization of polymorphic microsatellite DNA markers for Sasa senanensis (Poaceae: Bambuseae) Reviewed

Yuko Miyazaki, Naoki Ohnishi, Kimiko Hirayama, Junco Nagata

CONSERVATION GENETICS 10 ( 3 ) 585 - 587 2009.6

Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER

Sasa senanensis is a dwarf bamboo species distributed on the floors of cool temperate forests in Japan and adjacent regions. We isolated eight polymorphic microsatellite loci from this species. The number of alleles ranged from two to eight and the observed heterozygosity per locus from 0.13 to 0.74. Seven of the eight loci were also polymorphic in Sasa nipponica. Most of these markers were successfully amplified in other dwarf bamboo species. These markers will be useful for investigating clonal structure and population genetics in some dwarf bamboo species.

DOI： 10.1007/s10592-008-9575-4

Phylogeographical analysis by genotyping chloroplast DNA in Zelkova serrata

Fukatsu Eitaro, Shimada Hiromasa, Takii Tadato, Kabemura Yuji, Ubukata Masatoshi, Takahashi Makoto, Nakada Ryogo, Yano Keisuke, Watanabe Atsushi, Koyama Yasuhiro, Odani Jiro, Saito Maki, Miyazaki Yuko

The Japanese Forest Society Congress 119 40 - 40 2008

Allocation of photo-assimilated C-13 from reproductive and non-reproductive shoots to fruits in Styrax obassia Reviewed

Yuko Miyazaki, Tsutom Hiura, Ryo Funada

PLANT SPECIES BIOLOGY 22 ( 1 ) 53 - 57 2007.4

Allocation of resources to reproduction in Styrax obassia in a masting year Reviewed

Y Miyazaki, T Hiura, E Kato, R Funada

ANNALS OF BOTANY 89 ( 6 ) 767 - 772 2002.6

Language：English Publishing type：Research paper (scientific journal) Publisher：OXFORD UNIV PRESS

An analysis is presented of three possible pathways of reproductive allocation, namely, allocation of resources to reproductive organs from reproductive shoots, from non-reproductive shoots and from the main trunk. These pathways were examined by comparing the amount of storage starch in reproductive shoots, non-reproductive shoots and the main trunk in Styrax obassia, a typical masting tree species, during a year of little flowering (1999) and in a mass-flowering year (2000), In addition, we measured rates of light-saturated photosynthesis in leaves of reproductive and non-reproductive shoots to examine the contribution of photosynthetic production to reproductive costs. In both the main trunk and non-reproductive shoots the pattern of seasonal variation in the amount of starch did not differ between 1999 and 2000. However, in the mass-flowering year, the amount of starch in the reproductive shoots was less than that in non-reproductive shoots during the growing season. Thus, reproductive shoots bore most of the cost of reproduction, although non-reproductive shoots and the main trunk also bore some of the cost. Mass-based rates of light-saturated photosynthesis of the leaves of reproductive shoots were significantly higher than those of non-reproductive shoots during both the flowering and the fruiting period. However, leaves of reproductive shoots had a significantly smaller area, a lower mass per area, and lower concentrations of nitrogen than leaves of non-reproductive shoots, although the number of leaves did not differ between the two types of shoots. Therefore, the amount of photosynthate per shoot was significantly lower in reproductive shoots than in non-reproductive shoots. These results suggest that the cost of reproduction depends predominantly on storage starch in reproductive shoots, although it is still unclear how much photosynthate is allocated to reproductive organs from non-reproductive shoots. (C) 2002 Annals of Botany Company.

DOI： 10.1093/aob/mcf107

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