Jin Murata

Systematics and biogeography of Lathyrus (Leguminosae) based on internal transcribed spacer and cpDNA sequence data.

Lathyrus (Leguminosae; Papilionoideae) is the largest genus in tribe Fabeae and exhibits an intriguing extratropical distribution. We studied the systematics and biogeography of Lathyrus using sequence data, from accessions representing 53 species, for the internal transcribed spacer plus 5.8S-coding region of nuclear ribosomal DNA as well as the trnL-F and trnS-G regions of chloroplast DNA. Our results generally supported recent morphology-based classifications, resolving clades corresponding to sections Lathyrus and Lathyrostylis, but question the monophyly of the large, widespread section Orobus sensu Asmussen and Liston. Sections Orobus, Aphaca, and Pratensis form a predominantly northern Eurasian-New World clade. Within this clade, the North American and eastern Eurasian species, including both Holarctic species (L. palustris and L. japonicus), form a transberingian clade of relatively recent origin and diversification. The South American Notolathyrus group is distant from this transberingian lineage and should be reinstated as a distinct section within the northern Eurasian-New World clade. The Notolathyrus lineage reached the New World most probably through long-distance dispersal from Eurasia. The remaining sections in the genus are centered on the Mediterranean region.

New resveratrol oligomers in the stem bark of Vatica pauciflora

Abstract Five new resveratrol oligomers; pauciflorols A–C ( 1–3 ), isovaticanols B ( 6 ) and C ( 8 ), and three new oligostilbene glucosides; pauciflorosides A ( 11 ), B ( 13 ), C ( 14 ), were isolated from the stem bark of Vatica pauciflora (Dipterocarpaceae) together with known 17 resveratrol oligomers ( 4, 5, 7, 9, 10, 12 and 15–25 ) and bergenin ( 26 ). The structures of isolates were established on the basis of detailed spectroscopic analysis. The typical and characteristic spectral properties of some resveratrol oligomers were also discussed.

Molecular Phylogeny of Aristolochia sensu lato (Aristolochiaceae) based on Sequences of rbcL, matK, and phyA Genes, with Special Reference to Differentiation of Chromosome Numbers

Abstract The genus Aristolochia sensu lato contains over 400 species from warm temperate to tropical regions worldwide. Taxonomic treatments of Aristolochia have been ambiguous and controversial. In a recent cladistic analysis based on morphological characters, it was proposed that the genus should be divided into four genera in two subtribes. To reconsider the systematics of Aristolochia sensu lato, we reconstructed its phylogeny based on nucleotide sequences of the chloroplast rbcL gene and the nuclear-encoded phytochrome A (phyA) gene for 19 representative species and the chloroplast matK gene of over 80 species. All phylogenetic trees produced with the three genes indicate that Aristolochia sensu lato is a monophyletic group, consisting of two lineages that correspond to the subtribes Aristolochiinae and Isotrematinae. The matK phylogeny shows that each of the lineages includes two sublineages. The Aristolochiinae clade is composed of the Aristolochia sensu stricto and Pararistolochia clades, and the Isotrematinae clade of the Isotrema and Endodeca clades. Chromosome numbers, including newly reported counts for 30 species, are predominantly congruent with the phylogeny: the Aristolochiinae clade shows chromosome numbers of 2n = 6, 12, 14, or 16, while the Isotrematinae clade is characterized by 2n = 32. In the Isotrematinae clade, the paralogous relationships of the phyA gene suggest that polyploidization might have occurred.

Hybridization and polyploidy of an aquatic plant, Ruppia (Ruppiaceae), inferred from plastid and nuclear DNA phylogenies

UNLABELLED 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.

Stilbene derivatives from Gnetum gnemon Linn.

Four stilbene derivatives, gnemonols K and L (resveratrol trimers), M (isorhapontigenin dimer), and gnemonoside K (glucoside of resveratrol trimer) together with eleven known stilbenoids and a lignan were isolated from the acetone, methanol and 70% methanol soluble parts of the root of Gnetum gnemon (Gnetaceae). The structures of the isolates were determined by spectral analysis. The antioxidant activity of the stilbenoids on lipid peroxide inhibition and super oxide scavenging activity were also investigated.

Phylogeography and genetic structure of Hibiscus tiliaceus— speciation of a pantropical plant with sea-drifted seeds

Phylogenetic relationships and the spatial genetic structure of a pantropical plant with sea‐drifted seeds, Hibiscus tiliaceus L., and its allied species were investigated. The combined distribution range of these species is over almost the entire littoral area of the tropics worldwide, which might result from the dispersal of their sea‐drifted seeds and from recurrent speciation in local populations. A phylogenetic tree constructed using the nucleotide sequences of a c. 7500‐bp portion of chloroplast DNA suggested the possibility that recurrent speciation from H. tiliaceus has given rise to all of its allied species. Three major sequence haplotypes of H. tiliaceus had wide and overlapping distributions throughout the Pacific, Atlantic and Indian Ocean regions. This distribution pattern was also confirmed by PCR‐SSCP (polymerase chain reaction amplification with single‐strand conformation polymorphism) and PCR‐SSP (PCR amplification with sequence specific primers) analyses performed on more than 1100 samples from 65 populations worldwide. Statistical analysis using FST and analysis of molecular variance did not show significant genetic differentiation among the H. tiliaceus populations in the three oceanic regions. The results reported here suggested substantial gene flow occurred between populations in the different oceanic regions due to sea‐drifted seeds. A strong genetic difference between the Pacific and Atlantic populations of Hibiscus pernambucensis Arruda was observed, which indicates that gene flow in this species between the two regions has been prevented. The wide and dominant distribution of a haplotype shared by H. pernambucensis and H. tiliaceus in the Atlantic region suggests significant introgression between the two species in this region.

A chloroplast phylogeny of Arisaema (Araceae) illustrates Tertiary floristic links between Asia, North America, and East Africa

The evolution of Arisaema is reconstructed, based on combined sequences (2048 aligned bases) from the chloroplast trnL intron, trnL-trnF spacer, and rpl20-rps12 spacer obtained for species from all 11 sections, including sectional type species and geographically disjunct East African and North American/Mexican species. Analyses were rooted with a representative sample of the closest outgroups, Pinellia and Typhonium, to rigorously test the monophyly of Arisaema. Sections in Arisaema are mostly based on leaf, stem, and inflorescence characters and, with one exception, are not rejected by the molecular data; however, statistical support for sectional relationships in the genus remains poor. Section Tortuosa, which includes eastern North American A. dracontium and Mexican A. macrospathum, is demonstrably polyphyletic. The third New World species, A. triphyllum, also occurs in eastern North America and groups with a different Asian clade than do A. dracontium/A. macrospathum. The genus thus appears to have entered North America twice. Fossil infructescences similar to those of A. triphyllum are known from approximately 18 million-year-old deposits in Washington State and can serve to calibrate a molecular clock. Constraining the age of A. triphyllum to 18 million years (my) and applying either a semiparametric or an ultrametric clock model to the combined data yields an age of approximately 31-49 my for the divergence of A. dracontium/A. macrospathum from their Asian relatives and of 19-32 my for the divergence between African A. schimperianum and a Tibetan/Nepalese relative. The genus thus provides an example of the Oligocene/Miocene floristic links between East Africa, Arabia, the Himalayan region, China, and North America. The phylogeny also suggests secondary loss of the environmental sex determination strategy that characterizes all arisaemas except for two subspecies of A. flavum, which have consistently bisexual spathes. These subspecies are tetraploid and capable of selfing, while a third subspecies of A. flavum is diploid and retains the sex-changing strategy. In the molecular trees, the sex-changing subspecies is sister to the two non-sex-changing ones, and the entire species is not basal in the genus.

Chloroplast DNA variation and geographical structure of the Aristolochia kaempferi group (Aristolochiaceae)

The present study documents cpDNA variation in the Aristolochia kaempferi group (Aristolochiaceae), which consists of one Chinese and all Japanese and Taiwanese species of the subgenus Siphisia. In a phylogenetic analysis based on the nucleotide sequences of the matK gene, and the atpB-rbcL and trnS-trnG intergenic spacer regions, 38 haplotypes were recognized in the A. kaempferi group and as many as 24 within A. kaempferi. This is the most haplotypes reported for a single species to date. Although six highly significant major clades were identified in the phylogenetic analysis, they were not congruent with previous classifications. This might be attributed to the specific speciation process, such as convergent evolution, incomplete lineage sorting, and/or reticulate evolution. The six major clades had a clear geographical distribution pattern and were significantly associated with geographical distribution of haplotypes in a nested clade analysis and AMOVA. The results allow us to deduce a scenario in which multiple contractions and expansions of the geographical ranges brought about by Quaternary climatic oscillations affected the patterns of genetic diversity. The present geographic patterns of haplotype distribution within the A. kaempferi group can be explained by the last postglacial range expansion from different refugia, and the boundaries may be suture zones.

Allozyme analysis of the hybrid origin of Arisaema ehimense (Araceae).

Allozyme diversity was examined in the Japanese jack-in-the pulpit species, Arisaema serratum and A. tosaense, and their putative hybrid species, A. ehimense (all diploid). Arisaeme ehimense contains mostly alleles found in one or both of the putative parent species but few unique alleles, partially supporting the hypothesis that A. ehimense is of hybrid origin from the two species, although the possibility that A. ehimense arose via divergent speciation cannot be excluded. Because only limited information was gained from the survey of allozyme variation, additional taxon-specific markers from A. serratum and A. tosaense are required to test rigorously the hybrid origin of A. ehimense. A phenogram based on allele frequencies suggested that introgression occurs between A. serratum and A. tosaense where these species are sympatric.

Gene flow and population subdivision in a pantropical plant with sea‐drifted seeds Hibiscus tiliaceus and its allied species: evidence from microsatellite analyses

The genetic differentiation and structure of Hibiscus tiliaceus, a pantropical plant with sea‐drifted seeds, and four allied species were studied using six microsatellite markers. A low level of genetic differentiation was observed among H. tiliaceus populations in the Pacific and Indian Ocean regions, similar to the results of a previous chloroplast DNA (cpDNA) study. Frequent gene flow by long‐distance seed dispersal is responsible for species integration of H. tiliaceus in the wide distribution range. On the other hand, highly differentiated populations of H. tiliaceus were detected in West Africa, as well as of Hibiscus pernambucensis in southern Brazil. In the former populations, the African continent may be a geographical barrier that prevents gene flow by sea‐drifted seeds. In the latter populations, although there are no known land barriers, the bifurcating South Equatorial Current at the north‐eastern horn of Brazil can be a potential barrier to gene flow and may promote the genetic differentiation of these populations. Our results also suggest clear species segregation between H. tiliaceus and H. pernambucensis, which confirms the introgression scenario between these two species that was suggested by a previous cpDNA study. Our results also provide good evidence for recent transatlantic long‐distance seed dispersal by sea current. Despite the distinct geographical structure observed in the cpDNA haplotypes, a low level of genetic differentiation was found between Pacific and Atlantic populations of H. pernambucensis, which could be caused by transisthmian gene flow.