Floral structure and development in Nartheciaceae (Dioscoreales), with special reference to ovary position and septal nectaries.

We present a comparative study of the floral structure and development of Nartheciaceae, a small dioscorealean family consisting of five genera (Aletris, Lophiola, Metanarthecium, Narthecium, and Nietneria). A noticeable diversity existed in nine floral characters. Analyses of their respective character states in the light of a phylogenetic context revealed that the flowers of Nartheciaceae, whose plesiomorphies occur in Aletris and Metanarthecium, have evolved toward in all or part of Lophiola, Narthecium, and Nietneria: (1) loss of a perianth tube; (2) stamen insertion at the perianth base; (3) congenital carpel fusion; (4) loss of the septal nectaries; (5) unilocular style; (6) unfused lateral carpellary margins in the style; (7) flower with the median outer tepal on the abaxial side; (8) flower with moniliform hairs; and (9) flower with weak monosymmetry. We further found that, as the flowers developed, the ovary shifted its position from inferior to superior. As a whole, their structure changes suggest that the Nartheciaceae flowers have evolved in close association with pollination and seed dispersal. By considering inferior ovaries and the presence of septal nectaries as plesiomorphies of Nartheciaceae, we discussed evolution of the ovary position and septal nectaries in all the monocots.

Evolutionary timescale of monocots determined by the fossilized birth-death model using a large number of fossil records.

Although the phylogenetic relationships between monocot orders are sufficiently understood, a timescale of their evolution is needed. Several studies on molecular clock dating are available, but their results have been biased by their calibration schemes. Recently, the fossilized birth-death model, a type of Bayesian dating method, was proposed, and it does not require prior calibration and allows the use all available fossils. Using this model, we conducted divergence-time estimations of monocots to explore their evolutionary timeline without calibration bias. This is the first application of this model to seed plants. The dataset contained the matK and rbcL chloroplast genes of 118 monocot genera covering all extant orders. We employed information from 247 monocot fossils, which exceeded previous dating analyses that used a maximum of 12 monocot fossils. The crown group of monocots was dated to approximately the Late Jurassic-Early Cretaceous periods, and most extant monocot orders were estimated to diverge throughout the Early Cretaceous. Our results overlapped with the divergence time of insect lineages, such as beetles and flies, suggesting an association with pollinators in early monocot evolution. In addition, we proposed three new orders based on divergence time: Orchidales separated from Asparagales and Tofieldiales and Arales separated from Aslimatales.

New flavonol glycosides from the leaves of Triantha japonica and Tofieldia nuda.

Two new flavonol glycosides were isolated from the leaves of Triantha japonica, together with eight known flavonols, kaempferol 3-O-sophoroside, kaempferol 3-O-sambubioside, kaempferol 3-O-glucosyl-(1 --> 2)-[glucosyl-(1 --> 6)-glucoside], quercetin 3-O-sophoroside, quercetin 3-O-sambubioside, isorhamnetin 3-O-glucoside, isorhamnetin 3-O-sophoroside and isorhamnetin 3-O-sambubioside. The new compounds were identified as kaempferol 3-O-beta-xylopyranosyl-(1 --> 2)-[beta-glucopyranosyl-(1 --> 6)-beta-glucopyranoside] (1) and isorhamnetin 3-O-beta-xylopyranosyl-(1 --> 2)-[beta-glucopyranosyl-(1 --> 6)-beta-glucopyranoside] (3) by UV, LC-MS, acid hydrolysis, and 1H and 13C NMR spectroscopy. Another two new flavonol glycosides were isolated from theleaves of Tofieldia nuda, and identified as kaempferol 3-O-beta-glucopyranosyl-(1 --> 2)-[beta-glucopyranosyl-(1 --> 6)-beta-galactopyranoside] (4) and quercetin 3-O-beta-glucopyranosyl-(1 --> 2)-[beta-glucopyranosyl-(1 --> 6)-beta-galactopyranoside] (5). Though the genera Triantha and Tofieldia were treated as Tofieldia sensu lato, they were recently divided into two genera. It was shown by this survey that their flavonoid composition were also different to each other.

Phylogenetic analyses and chromosome evolution in Convallarieae (Ruscaceae sensu lato), with some taxonomic treatments.

The tribe Convallarieae, comprising 10 genera and 95 species, has recently been transferred from its own family to Ruscaceae sensu lato. In this study, sequence data from trnK and rbcL were analyzed for 19 species in 8 genera, and chromosome morphology was analyzed for 17 species in 7 genera. The parsimony analysis of trnK and rbcL sequences showed that Convallarieae are monophyletic. Although early branches did not receive strong bootstrap support, Convallaria diverged at the first branch, followed by Speirantha. The rest of the tribe was split into three, well-supported clades: one with Reineckea, the second with Campylandra and Rohdea, and the third with Tupistra, Tricalistra, and Aspidistra. Two monotypic genera, Rohdea and Tricalistra, were embedded in a clade of Campylandra and of Tupistra, respectively. Three karyotypes were distinguished in the tribe on the basis of the basic number and morphology of metaphase chromosomes: Convallaria type (with x=19 and unimodal chromosome length), Tupistra type (with x=19 and trimodal chromosome length), and Aspidistra-elatior type (with x=18 and trimodal chromosome length). The character-state distribution in the molecular tree showed that the Convallaria type is plesiomorphic, from which was derived the Tupistra type and subsequently the Aspidistra-elatior type. Taxonomic treatments to transfer Campylandra to Rohdea and Tricalistra to Tupistra are also given.

Molecular phylogeny of monocotyledons inferred from combined analysis of plastid matK and rbcL gene sequences.

Using matK and rbcL sequences (3,269 bp in total) from 113 genera of 45 families, we conducted a combined analysis to contribute to the understanding of major evolutionary relationships in the monocotyledons. Trees resulting from the parsimony analysis are similar to those generated by earlier single or multiple gene analyses, but their strict consensus tree provides much better resolution of relationships among major clades. We find that Acorus (Acorales) is a sister group to the rest of the monocots, which receives 100% bootstrap support. A clade comprising Alismatales is diverged as the next branch, followed successively by Petrosaviaceae, the Dioscoreales-Pandanales clade, Liliales, Asparagales and commelinoids. All of these clades are strongly supported (with more than 90% bootstrap support). The sister-group relationship is also strongly supported between Alismatales and the remaining monocots (except for Acorus) (100%), between Petrosaviaceae and the remaining monocots (except for Acorus and Alismatales) (100%), between the clade comprising Dioscoreales and Pandanales and the clade comprising Liliales, Asparagales and commelinoids (87%), and between Liliales and the Asparagales-commelinoids clade (89%). Only the sister-group relationship between Asparagales and commelinoids is weakly supported (68%). Results also support the inclusion of Petrosaviaceae in its own order Petrosaviales, Nartheciaceae in Dioscoreales and Hanguanaceae in Commelinales.