Godo T.,Botanic Gardens of Toyama |
Komori M.,Botanic Gardens of Toyama |
Nakaoki E.,Toyama Prefectural University |
Yukawa T.,Tsukuba Botanical Garden |
Miyoshi K.,Akita Prefectural University
In Vitro Cellular and Developmental Biology - Plant | Year: 2010
The effects of culture conditions on the asymbiotic germination of mature seeds of Calanthe tricarinata Lindl., an endangered terrestrial cool-climate orchid, were examined. Specifically, conditions such as illumination, temperature, and the addition of plant growth regulators to the medium were studied. Mature seeds were harvested from plants that had been collected in Toyama Prefecture, Japan, and maintained at the Botanic Gardens of Toyama. Solidified "New Dogashima" medium was used as the basal medium, and it was supplemented with 6-benzyladenopurine (BA) or α-naphthalene acetic acid (NAA). White light at 40 μmol m-2 s-1, with a 16-h photoperiod, inhibited the germination of seeds by 53-80%, as compared to dark controls in genotypes examined. The optimal temperature for the germination of seeds in darkness was 20°C and the germination frequency reached 60%, whereas it was only 28% at 25°C. While both NAA and BA stimulated germination, BA was more effective than NAA. After storage for 18 mo at 5°C, seeds incubated on medium that contained 0. 2 mg l-1 BA germinated at a frequency of 36%, which was twice that of seeds grown without any plant growth regulators. The frequency of subsequent germination decreased during storage of seeds at 5°C for approximately 2 yr, dropping from 61% to 13%. The protocorms obtained in this study were developed to plantlets readily after transferring to fresh 1/2 MS medium without any plant growth regulators. They were successfully acclimatized in green house after two to three subcultures in vitro. The significant role of a reproducible protocol for the germination of mature seeds is discussed in terms of the ex situ conservation of endangered orchid species. © 2010 The Society for In Vitro Biology.
Gale S.W.,Kochi Prefectural Makino Botanical Garden |
Maeda A.,Kochi Prefectural Makino Botanical Garden |
Chen C.-I.,Taitung District Agricultural Research and Extension Station |
Yukawa T.,Tsukuba Botanical Garden
Journal of Plant Research | Year: 2010
An understanding of the extent to which reproductive strategy and seed dispersal lead to the structuring of genetic diversity in space is required when planning measures towards the conservation of endangered plant species. In this study, genetic structure in the endangered terrestrial orchid Nervilia nipponica was investigated using amplified fragment length polymorphisms following extensive sampling throughout the species' range in Japan and intensive sampling at a single population. Limited diversity was found within the species as a whole, but significant structuring was detected between populations. One genotype was common to two widely separated sites, possibly indicative of long-range dispersal. Significant structure was also detected at the intensively sampled site, as a result of the presence of two distinct putative clones. These findings are consistent with observations of the species' ability to set seed autogamously and propagate vegetatively. Given the strong colonising capability inferred for the species, attention should focus on identifying and securing habitat conditions conducive to seed germination and seedling establishment in the development of a conservation strategy. As presently circumscribed, N. nipponica is shown to comprise two polyphyletic taxa, both endemic to Japan, and both distinct from N. taiwaniana, a species that some authors have considered conspecific. © 2010 The Botanical Society of Japan and Springer.
Ito Y.,University of Tokyo |
Ohi-Toma T.,University of Tokyo |
Murata J.,University of Tokyo |
Tanaka N.,Tsukuba Botanical Garden
American Journal of Botany | Year: 2010
Premise of the study: The monogeneric family Ruppiaceae is found primarily in brackish water and is widely distributed on all continents, many islands, and from subartic to tropical zones. Ruppia taxonomy has been confusing because of its simplified morphology yet high phenotypic plasticity and the existence of polyploidy and putative hybrids. This study addresses the current classification of species in the genus, the origin of putative hybrids and polyploids, and the distribution of Ruppia species. Methods: Separate molecular phylogenetic analyses using plastid DNA and nuclear-encoded PHYB data sets were performed after chromosome observations. Key results: The resultant trees were largely congruent between genomes, but were incongruent in two respects: the first incongruence may be caused by long outgroup branches and their effect on ingroup rooting, and the second is caused by the existence of heterogeneous PHYB sequences for several accessions that may reflect several independent hybridization events. Several morphological species recognized in previous taxonomic revisions appear paraphyletic in plastid DNA and PHYB trees. Conclusions: Given the molecular phylogenies, and considering chromosome number and morphology, three species and one species complex comprising six lineages were discerned. A putative allotriploid, an allotetraploid, and a lineage of hybrid origin were identified within the species complex, and a hybrid was found outside the species complex, and their respective putative parental taxa were inferred. With respect to biogeography, a remarkably discontinuous distribution was identified in two cases, for which bird-mediated seed dispersal may be a reasonable explanation. © 2010 Botanical Society of America.
Okuyama Y.,Tsukuba Botanical Garden |
Tanabe A.S.,University of Tsukuba |
Kato M.,Kyoto University
Molecular Biology and Evolution | Year: 2012
The reconstruction of an ancient polyploidization history is often challenging, although it is a crucial step in clarifying the mechanisms underlying the contemporary success and diversity of polyploids. Phylogenetic relationships of duplicated gene pairs of polyploids, with respect to their orthologs in related diploids, have been used to address this problem, but they often result in conflicting topologies among different genes. Asimitellaria is an East Asian endemic tetraploid lineage of perennials (genus Mitella; Saxifragaceae) that has diversified in riparian habitats. Phylogenetic analyses of four nuclearencoded, single-copy (per haploid) genes GBSSI-A, GBSSI-B, GS-II, and PepCK all supported a single allopolyploid origin of Asimitellaria, but they did not lead to a consensus about which diploid lineage gave rise to each of the Asimitellaria subgenomes. To address this issue, we used an integrated approach, whereby the four gene data sets and an additional nuclear ribosomal external transcribed spacer and internal transcribed spacer (including a 5.8S ribosomal DNA) data set were concatenated in all possible combinations, and the most probable data combination was determined together with the phylogenetic inference. This resulted in relatively robust support for the two closely related North American diploid species as the ancestral lineages of the Asimitellaria subgenomes, suggesting ancient intercontinental migration of the diploid or tetraploid lineages and subsequent tetraploid diversification in the Japanese Archipelago. The present approach enabled sorting out the duplicated genes into their original combinations in their preduplication ancestors under a maximum-likelihood framework, and its extension toward genome sequencing data may help in the reconstruction of ancestral, preduplicated, whole-genome structures. © The Author 2011.
Shirakawa M.,Kyoto University |
Ueda H.,Kyoto University |
Shimada T.,Kyoto University |
Koumoto Y.,Kyoto University |
And 6 more authors.
Plant Journal | Year: 2010
SYP2 proteins are a sub-family of Qa-SNAREs (soluble N-ethylmaleimide- sensitive factor attachment protein receptors) that may be responsible for protein trafficking between pre-vacuolar compartments (PVC) and vacuoles. Arabidopsis thaliana SYP22/VAM3/SGR3 and SYP21/PEP12 proteins function independently, but are both reported to be essential for male gametophytic viability. Here, we systematically examined the redundancy of three SYP2 paralogs (i.e. SYP21, 22 and 23) using a Col-0 ecotype harboring a SYP2 paralog (SYP23/PLP) that lacked a transmembrane domain. Surprisingly, no visible phenotypes were observed, even in the double knockout syp21/pep12 syp23/plp. Deficiency of either SYP21/PEP12 or SYP23/PLP in the syp22 background resulted in a defect in vacuolar protein sorting, characterized by abnormal accumulation of protein precursors in seeds. SYP21/PEP12 knockdown enhanced the syp22 phenotype (i.e. semi-dwarfism, poor leaf vein development and abnormal development of myrosin cells), and additional knockout of SYP23/PLP further aggravated the phenotype. A GFP-SYP23/PLP fusion localized to the cytosol, but not to the PVC or vacuolar membrane, where SYP21/PEP12 or SYP22/VAM3, respectively, were localized. Immunoprecipitation analysis showed that SYP23/PLP interacted with the vacuolar Qb- and Qc-SNAREs, VTI11 and SYP5, respectively, suggesting that SYP23/PLP is able to form a SNARE complex anchoring the membrane. Unexpectedly, we found that expression of multiple copies of a genomic fragment of SYP23/PLP suppressed the abnormal syp22-3 phenotype. Thus, SYP2 proteins, including cytosolic SYP23/PLP, appear to function redundantly in vacuolar trafficking and plant development. © 2010 The Authors. The Plant Journal © 2010 Blackwell Publishing Ltd.