翅萼龙胆中的两个寡聚裂环烯醚萜甙

从翅萼龙胆的全株中分离得到两个新的寡聚裂环烯醚萜甙：翅萼龙胆甙Ｉａ和Ｉｂ,其结构通过光谱分析推定。     

Secoiridoids from Exacum tetragonum

Extraction of Exacum tetragonum furnished the secoiridoids gentiopicroside and methylgrandifloroside, the latter in the form of its methyl ester.     

Phylotranscriptomics of Swertiinae (Gentianaceae) reveals that key floral traits are not phylogenetically correlated

Establishing how lineages with similar traits are phylogenetically related remains critical for understanding the origin of biodiversity on Earth. Floral traits in plants are widely used to explore phylogenetic relationships and to delineate taxonomic groups. The subtribe Swertiinae (Gentianaceae) comprises more than 350 species with high floral diversity ranging from rotate to tubular corollas and possessing diverse nectaries. Here we performed phylogenetic analysis of 60 species from all 15 genera of the subtribe Swertiinae sensu Ho and Liu, representing the range of floral diversity, using data from the nuclear and plastid genomes. Extensive topological conflicts were present between the nuclear and plastome trees. Three of the 15 genera represented by multiple species are polyphyletic in both trees. Key floral traits including corolla type, absence or presence of lobe scales, nectary type, nectary position, and stigma type are randomly distributed in the nuclear and plastome trees without phylogenetic correlation. We also revealed the likely ancient hybrid origin of one large clade comprising 10 genera with diverse floral traits. These results highlight the complex evolutionary history of this subtribe. The phylogenies constructed here provide a basic framework for further exploring the ecological and genetic mechanisms underlying both species diversification and floral diversity.     

Better than nothing: Evolution of autonomous selfing under strong inbreeding depression in an alpine annual from the Qinghai–Tibet Plateau

In plants with infrequent pollinator services, the benefits of reproductive assurance could be eroded by severe ovule discounting and inbreeding depression (ID). However, it remains unclear how selfing evolves under complete pollinator failure and strong ID. We examined the mating system and ID under netting and robbing conditions in Comastoma pulmonarium (Turcz.) Toyok. (Gentianaceae), an alpine annual experiencing a high ratio of nectar robbery on the Qinghai–Tibet Plateau.Comastoma pulmonarium produced seeds via selfing at the study site. No pollinator was observed and thus the nectar was consumed exclusively by robbers. Inbreeding depression occurred in the life stages of seed mass and germination, and the cumulative ID was much higher than 0.5 under netting and robbing conditions. Overall, in comparison with netting, the magnitude of ID under robbing conditions tended to decrease. Our results suggested that selfing could assure reproduction for plants under complete pollinator failure and strong ID, supporting the “better than nothing” role of selfing and providing one of the few cases of the evolution of selfing under strong ID.     

Experimental inbreeding reduces seed production and germination independent of fragmentation of populations of Swertia perennis

We studied effects of inbreeding on the early fitness measures seed production and germination in Swertia perennis L. (Gentianaceae), a locally abundant specialist of fen grasslands, which have been greatly fragmented in Switzerland. We further tested whether such effects differed between populations of different size and isolation. We studied effects of free pollination, hand-outcrossing and hand-selfing on 160 plants in 16 populations in large, in small barely isolated, and in small isolated habitat islands. We found a distinct gradient in experimental outcomes from free pollination to hand-outcrossing to hand-selfing. Compared with free pollination, selfing reduced the number of seeds per capsule by 22% (P < 0.01), the seed/ovule ratio by 26% (P < 0.001), seed mass by 25% (P < 0.001) and germination percentage by 23% (P < 0.05). The outcome of hand-outcrossing was intermediate for all traits. The reduction in early fitness components after selfing is most likely due to inbreeding depression. Higher seed production and germination after free pollination than after hand-outcrossing may be due to a larger number of pollen donors involved in free pollination or due to higher quality of free pollen because of lower relatedness of parent plants. Moreover, the fact that seed production was highest after free pollination indicates that S. perennis is not pollen limited. Pollination treatment effects did not differ between different island types. Hence, there are no indications that early inbreeding depression was purged from more strongly fragmented populations.Wir untersuchten die Auswirkungen von Inzucht auf die frühen Fitnessmerkmale Samenproduktion und Keimung bei der lokal häufigen Swertia perennis L. (Gentianaceae), einer Pflanze der in der Schweiz stark fragmentierten Flachmoore. Um zu untersuchen, ob sich solche Auswirkungen in verschieden großen und unterschiedlich isolierten Populationen unterscheiden, verglichen wir die Auswirkungen von freier Bestäubung, Handfremdbestäubung und Handselbstbestäubung für 160 Pflanzen in 16 Populationen in großen, in kleinen wenig isolierten und in kleinen isolierten Habitatinseln. Wir fanden einen ausgeprägten Gradienten von freier Bestäubung über Fremdbestäubung von Hand zu Handselbstbestäubung: Im Vergleich zu freier Bestäubung war nach Selbstbestäubung die Anzahl Samen pro Kapsel um 22% (P < 0.01), der Samenansatz um 26% (P < 0.001), die Samenmasse um 25% (P < 0.001) und der Keimungserfolg um 23% (P < 0.05) herabgesetzt. Die Resultate der Handfremdbestäubung waren für alle Maße intermediär. Die Herabsetzung von Merkmalen früher Fitness von S. perennis nach Selbstbestäubung ist höchstwahrscheinlich eine Folge von Inzuchtdepression. Der im Vergleich zu Handfremdbestäubung nach freier Bestäubung höhere Fortpflanzungserfolg und die höhere Keimung könnten durch eine größere Anzahl zu freier Bestäubung beitragende Pollenspender oder durch geringere Verwandtschaft der in freier Bestäubung beteiligten Elternpflanzen bedingt sein. Dass die Samenproduktion nach freier Bestäubung am höchsten war, deutet auch darauf hin, dass S. perennis nicht pollenlimitiert ist. Die Effekte der Bestäubungsbehandlungen unterschieden sich nicht zwischen Populationen der verschiedenen Habitatinseltypen. Es gibt also keinen Hinweis darauf, dass frühe Inzuchtdepression aus kleinen und stärker isolierten Habitatinseln ausgemerzt wurde.     

大钟花属和黄秦艽属花部解剖

对大钟花属和黄秦艽属进行了花部解剖学研究,并以此讨论了它们的系统演化关系。大钟花属和黄秦艽属的雌花部分花萼维管束与花冠维管束来源于同一维管束迹,而雄蕊维管束来源于雄蕊迹,每心皮具1条背维管束2条腹维管束,因此,花被维管束为融合型;黄秦艽属的雄花每个花萼、花瓣和雄蕊的维管束均来源于单个维管束迹,每心皮具1条背维管束2条腹维管束,属于基本型。从花部解剖结构看出,大钟花属与假龙胆演化支关系较近;黄秦艽属较獐牙菜属进化。     

Generic delimitation and phylogenetic relationships within the subtribe Chironiinae (Chironieae: Gentianaceae), with special reference to Centaurium: evidence from nrDNA and cpDNA sequences

To better understand the evolutionary history of the genus Centaurium and its relationship to other genera of the subtribe Chironiinae (Gentianaceae: Chironieae), molecular analyses were performed using 80 nuclear ribosomal ITS and 76 chloroplast trnLF (both the trnL UAA intron and the trnL-F spacer) sequences. In addition, morphological, palynological, and phytochemical characters were included to a combined data matrix to detect possible non-molecular synapomorphies. Phylogenetic reconstructions support the monophyly of the Chironiinae and an age estimate of ca. 22 million years for the subtribe. Conversely, both molecular data sets reveal a polyphyletic Centaurium, with four well-supported main clades hereafter treated as separate genera. The primarily Mediterranean Centaurium s.s. is closely related to southern African endemics Chironia and Orphium, and to the Chilean species Centaurium cachanlahuen. The resurrected Mexican and Central American genus Gyrandra is closely related to Sabatia (from eastern North America). Lastly, the monospecific genus Exaculum (Mediterranean) forms a monophyletic group together with the two new genera: Schenkia (Mediterranean and Australian species) and Zeltnera (all other indigenous American centauries). Several biogeographical patterns can be inferred for this group, supporting a Mediterranean origin followed by dispersals to (1) North America, Central America, and South America, (2) southern Africa (including the Cape region), and (3) Australia and Pacific Islands.     

Physiological and morphological traits associated with zinc efficiency in Exacum

Interspecific hybrids of Exacum exhibit variation in the expression of zinc efficiency. This research investigated the genetic basis for this variation and evaluated a series of physiological and morphological traits for their association with zinc efficiency. Chi-square analyses of self-pollinated progeny from both zinc-efficient and zinc-inefficient parents indicate a significant genetic component. One hundred percent of the progeny from the inefficient parent were classified as inefficient, while the progeny from the efficient parent segregated 32% inefficient to 68% efficient. Six plants from each phenotypic class (efficient and inefficient) of the efficient parent were utilized in analyses of plant traits. Statistically significant associations were identified between the zinc-efficient phenotype and mol Zn uptake mg^-1 root, root-to-shoot ratio, specific root length, mol Zn uptake cm^-2 root surface area, and Zn uptake cm^-1 root length. No association was identified between zinc-efficient phenotype and root diameter, transpiration rate, or H⁺ production. Zinc uptake cm^-1 root length had the greatest association with the zinc-efficiency phenotype and was able to discriminate the two phenotypic classes. We suggest that Zn uptake cm^-1 root length is the most significant factor explaining the variation between the zinc-efficient and zinc-inefficient phenotypes in Exacum.     

Variation and evolution of herkogamy in Exochaenium (Gentianaceae): implications for the evolution of distyly

Backgrounds and Aims

The spatial separation of stigmas and anthers (herkogamy) in flowering plants functions to reduce self-pollination and avoid interference between pollen dispersal and receipt. Little is known about the evolutionary relationships among the three main forms of herkogamy – approach, reverse and reciprocal herkogamy (distyly) – or about transitions to and from a non-herkogamous condition. This problem was examined in Exochaenium (Gentianaceae), a genus of African herbs that exhibits considerable variation in floral morphology, including the three forms of herkogamy.

Methods

Using maximum parsimony and maximum likelihood methods, the evolutionary history of herkogamic and non-herkogamic conditions was reconstructed from a molecular phylogeny of 15 species of Exochaenium and four outgroup taxa, based on three chloroplast regions, the nuclear ribosomal internal transcribed spacer (ITS1 and 2) and the 5·8S gene. Ancestral character states were determined and the reconstructions were used to evaluate competing models for the origin of reciprocal herkogamy.

Key results

Reciprocal herkogamy originated once in Exochaenium from an ancestor with approach herkogamy. Reverse herkogamy and the non-herkogamic condition homostyly were derived from heterostyly. Distylous species possessed pendent, slightly zygomorphic flowers, and the single transition to reverse herkogamy was associated with the hawkmoth pollination syndrome. Reductions in flower size characterized three of four independent transitions from reciprocal herkogamy to homostyly.

Conclusions

The results support Lloyd and Webb''s model in which distyly originated from an ancestor with approach herkogamy. They also demonstrate the lability of sex organ deployment and implicate pollinators, or their absence, as playing an important role in driving transitions among herkogamic and non-herkogamic conditions.     

Exchangeability of Colloidal Calcium in Milk with Soluble Calcium

Approximately 40% of the calcium existing in colloidal phase of skimmilk was estimated to be hardly exchanged with the calcium psesent in soluble phase by applying a radioisotopic technique. This type of calcium was designated hard-to-exchange calcium. Hard-to-exchange calcium was absent or nearly zero in calcium caseinate dispersion or colloidal phosphate-free milk, but was present in composite calcium caseinate phosphate dispersion. It is suggested that hard-to-exchange calcium is present in a part of colloidal phosphate portion of casein micelles.