High-intensity light promotes adaptive divergence of photosynthetic traits between sun-exposed and shaded populations in Saxifraga fortunei.

PREMISE: Light is essential for plants, and local populations exhibit adaptive photosynthetic traits depending on their habitats. Although plastic responses in morphological and/or physiological characteristics to different light intensities are well known, adaptive divergence with genetic variation remains to be explored. This study focused on Saxifraga fortunei (Saxifragaceae) growing in sun-exposed and shaded habitats. METHODS: We measured the leaf anatomical structure and photosynthetic rate of plants grown in their natural habitats and in a common greenhouse (high- and low-intensity light experimental sites). To assess differences in ecophysiological tolerance to high-intensity light between the sun and shade types, we evaluated the level of photoinhibition of photosystem II and the leaf mortality rate under high-intensity light conditions. In addition, population genetic analysis was conducted to investigate phylogenetic origins. RESULTS: Clear phenotypic differences were found between the sun and shade types despite their recent phylogenetic origin. The leaf anatomical structure and photosynthetic rate showed plastic changes in response to growing conditions. Moreover, the sun type had a well-developed palisade parenchyma and a higher photosynthetic rate, which were genetically fixed, and a lower level of photoinhibition under high-intensity light. CONCLUSIONS: Our findings demonstrate that light intensity is a selective pressure that can rapidly promote phenotypic divergence between the sun and shade types. While phenotypic changes in multiple photosynthetic traits were plastic, genetic divergence in specific traits related to adaptation to high-intensity light would be fundamental for ecotypic divergence to different light regimes.

A review of the genus Chrysosplenium as a traditional Tibetan medicine and its preparations.

ETHNOPHARMACOLOGICAL RELEVANCE: Plants of genus Chrysosplenium have a long history of application and are distributed in many countries, especially in Tibetan regions of China. The genus has been used locally in the treatment of various hepatobiliary diseases such as "Chiba disease" (related to cholecystitis, cholelithiasis, acute icteric hepatitis, and acute liver necrosis in modern medicine). AIM OF THE REVIEW: This review summarizes and critically analyzes the aspects of the botanical morphology and distribution, traditional uses, phytochemistry, pharmacological activities, quality control, and development status of preparations of the genus Chrysosplenium. Moreover, the future research direction and focus of the genus are also discussed. We hope to provide a valuable reference for researchers who are interested in the genus Chrysosplenium. MATERIALS AND METHODS: The relevant information of the genus Chrysosplenium was gathered through electronic databases from 1968 to 2021, including PubMed, Web of Science, ScienceDirect, Google Scholar, Springer, CNKI, and Wan Fang, as well as PhD, MSc thesis, Chinese Pharmacopoeia (2020 edition), Tibetan medicine monographs. In addition, plant names were verified by "The Plant List" (The Plant List Database, http://www.theplantlist.org). RESULTS: Based on existing studies of chemical compositions, more than 90 compounds have been identified from Chrysosplenium species, including flavonoids, triterpenoids, volatile oils, steroids, alkaloids, and other compounds. The highly hydroxylated and methoxylated flavonoids and triterpenoids are the main active components. In addition, many studies have shown that the extracts and some components isolated from the genus Chrysosplenium have a variety of pharmacological activities, such as anti-tumor, antibacterial, anti-viral, hepatoprotective, and insecticidal properties. Furthermore, there are only 9 preparations with Chrysosplenium species as one of the medicinal materials. Among these preparations, C. nudicaule is used more and other Chrysosplenium species are rarely involved. CONCLUSIONS: Most medicinal species of Chrysosplenium have not only good therapeutic effects in traditional uses, but also a great potential for development in modern pharmaceutical studies. However, the material basis and mechanism of action of this genus have not been well explained. Therefore, further systematic and comprehensive research on the genus Chrysosplenium is still required to provide a scientific basis for its clinical applications.

Pollination by fungus gnats and associated floral characteristics in five families of the Japanese flora.

Background and aims: Pollination by fungus gnats (Mycetophilidae and Sciaridae) is uncommon, but is nevertheless known to occur in 20 genera among eight angiosperm families. Because many fungus gnat-pollinated plants possess a dark red floral display, we hypothesized that fungus gnat pollination is more widespread among plants with similar floral display than currently known. We thus studied the pollination biology of flowers with dark red pigmentation in five families, focusing particularly on plants having small, flat, actinomorphic flowers with exposed nectaries and short stamens, because these floral characteristics mirror those of a known fungus gnat-pollinated genus (Mitella). Methods: We observed daytime and night-time floral visitors for a total of 194.5 h in Aucuba japonica (Garryaceae), Euonymus spp. (Celastraceae), Disanthus cercidifolius (Hamamelidaceae), Micranthes fusca (Saxifragaceae) and Streptopus streptopoides (Liliaceae). Visitors were categorized into functional groups, and a pollination importance index (PII) was calculated for each functional group based on visitation frequency, pollen load and behaviour on flowers. Key results: Fungus gnats were dominant among the 1762 insects observed (36-92 % depending on the plant species) and were the most important pollinators among all plants studied (PII: 0.529-1). Fungus gnat visits occurred during the daytime and, more frequently, at dusk. Most often, pollen grains became clumped on the ventral side of the head and/or thorax as the short-proboscid fungus gnats foraged on nectar and came into contact with anthers located close to the flower base. Conclusions: Pollination by fungus gnats is probably more common than previously thought, especially in habitats similar to those of the plants studied (moist forest understorey, streamside or subalpine meadow) where fungus gnats are abundant year-round. Our results further suggest that there may be a previously unnoticed association between fungus gnat pollination and dark red coloration, and a shared overall floral architecture among the plants studied.

Evolutionary radiations in the species-rich mountain genus Saxifraga L.

BACKGROUND: A large number of taxa have undergone evolutionary radiations in mountainous areas, rendering alpine systems particularly suitable to study the extrinsic and intrinsic factors that have shaped diversification patterns in plants. The species-rich genus Saxifraga L. is widely distributed throughout the Northern Hemisphere, with high species numbers in the regions adjacent to the Qinghai-Tibet Plateau (QTP) in particular the Hengduan Mountains and the Himalayas. Using a dataset of 297 taxa (representing at least 60% of extant Saxifraga species), we explored the variation of infrageneric diversification rates. In addition, we used state-dependent speciation and extinction models to test the effects of geographic distribution in the Hengduan Mountains and the entire QTP region as well as of two morphological traits (cushion habit and specialized lime-secreting glands, so-called hydathodes) on the diversification of this genus. RESULTS: We detected two to three rate shifts across the Saxifraga phylogeny and two of these shifts led to radiations within two large subclades of Saxifraga, sect. Ciliatae Haworth subsect. Hirculoideae Engl. & Irmsch. and sect. Porphyrion Tausch subsect. Kabschia Engl. GEOSSE analyses showed that presence in the Hengduan Mountains had a positive effect on diversification across Saxifraga. Influence of these mountains was strongest in Saxifraga sect. Ciliatae subsect. Hirculoideae given its pronounced distribution there, and thus the radiation in this group can be classified at least partially as geographic. In contrast, the evolution of the cushion life form and lime-secreting hydathodes had positive effects on diversification only in selected Saxifraga sections, including sect. Porphyrion subsect. Kabschia. We therefore argue that radiation in this group was likely adaptive. CONCLUSIONS: Our study underlines the complexity of processes and factors underpinning plant radiations: Even in closely related lineages occupying the same life zone, shifts in diversification are not necessarily governed by similar factors. In conclusion, alpine plant radiations result from a complex interaction among geographical settings and/or climatic modifications providing key opportunities for diversification as well as the evolution of key innovations.

Testing the influence of gravity on flower symmetry in five Saxifraga species.

Flower symmetry is considered a species-specific trait and is categorized in asymmetry, actinomorphic symmetry, bisymmetry and zygomorphic symmetry. Here we report on the intra-individual variation of flower symmetry in the genus Saxifraga and the influence of light, gravity and intrinsic factors on the development of flower symmetry. We tested five species-Saxifraga cuneifolia, Saxifraga imparilis, Saxifraga rotundifolia, Saxifraga stolonifera and Saxifraga umbrosa-concerning six flower parameters-angles between petals, petal length, petal pigmentation, angular position of carpels, movement of stamens and (only for S. imparilis and S. stolonifera) the length of the two lower elongated petals in regard to their position towards the stem. Specimens of all species were tested on a vertical clinostat as a gravity compensator, on a horizontal clinostat as a light incidence compensator and on a stationary control. The results show that the angle of incident light has no apparent impact on flower symmetry, whereas gravity affects the angular position of petals in S. cuneifolia and S. umbrosa and the petal colouration in S. rotundifolia. In S. cuneifolia and S. umbrosa, the absence of directional gravity resulted in the development of actinomorphic flowers, whereas the corresponding control flowers were zygomorphic. The development of flowers in S. rotundifolia was not altered by this treatment. The length of the two elongated petals in S. stolonifera and S. imparilis was not affected by gravity, but rather was determined by position of the flower within the inflorescence and resulted in asymmetrical flowers.

[Microscopic identification of tibetan medicinal herb "Songdi" (Saxifraga umbellulata var pectinata)].

OBJECTIVE: To establish a method of microscopic identification of Tibetan medicinal herb " Songdi" (Saxifraga umbellulata var. pectinata). METHOD: The different characteristics and microscopic identification of 4 species of Songdi were compared, including the main variety (Saxifraga umbellulata var. pectinata ) and approximate varieties (S. unguiculata, S. przewalskii and S. tanguTi,) were studied and compared. RESULT: The botanical anatomy characteristics of Saxifraga umbellulata var. pectinata (including roots, stems, leaves, flowers, stalks and fruits) have been measured. The methods for powder identifications and transverse section of stems root and leaves of four species of Songdi were established. CONCLUSION: Four species of Songdi can be identified by the growth pattern of basal leaves, type of hair, type of inflorescence, number of flowers, proportion of tissue structures in stem, form of pollen grains.

Splash-cup plants accelerate raindrops to disperse seeds.

The conical flowers of splash-cup plants Chrysosplenium and Mazus catch raindrops opportunistically, exploiting the subsequent splash to disperse their seeds. In this combined experimental and theoretical study, we elucidate their mechanism for maximizing dispersal distance. We fabricate conical plant mimics using three-dimensional printing, and use high-speed video to visualize splash profiles and seed travel distance. Drop impacts that strike the cup off-centre achieve the largest dispersal distances of up to 1 m. Such distances are achieved because splash speeds are three to five times faster than incoming drop speeds, and so faster than the traditionally studied splashes occurring upon horizontal surfaces. This anomalous splash speed is because of the superposition of two components of momentum, one associated with a component of the drop's motion parallel to the splash-cup surface, and the other associated with film spreading induced by impact with the splash-cup. Our model incorporating these effects predicts the observed dispersal distance within 6-18% error. According to our experiments, the optimal cone angle for the splash-cup is 40°, a value consistent with the average of five species of splash-cup plants. This optimal angle arises from the competing effects of velocity amplification and projectile launching angle.

Lobe-generating centres in the simple leaves of Myriophyllum aquaticum: evidence for KN1-like activity.

BACKGROUND AND AIMS: The mature morphology of most plants can usually be said to consist of three mutually exclusive organs: leaves, stems, and roots. The vast majority of mature morphologies may be easily grouped into one of these mutually exclusive categories. However, during very early stages of development and in many instances from inception, the division between organ categories becomes fuzzy due to the overlap in developmental processes that are shared between the aforementioned mutually exclusive categories. One such overlap has been described at the gene level where KNOXI homologues, transcription factors responsible for maintaining indeterminate cell fate, are expressed in the shoot apical meristem and during early stages of compound leaf development. This study characterizes the occurrence and spatial localization of mRNA of a KNOXI homologue, MaKN1, during the early stages of development in the simple leaves of Myriophyllum aquaticum, an aquatic angiosperm from the family Haloragaceae exhibiting pentamerous whorls of finely lobed leaves. METHODS: A 300-bp KNOXI fragment was sequenced from M. aquaticum and used in an RNA localization study to determine the temporal and spatial expression of KNOXI during the early stages of leaf lobe development in M. aquaticum. The developmental sequence of leaves of M. aquaticum was also described using scanning electron microscopy. KEY RESULTS: Lobe development of M. aquaticum occurs in two very distinct regions at the leaf base in an alternating fashion reminiscent of a distichous shoot system. It was discovered that MaKN1 expression is localized to both the shoot apical meristem and early stages of leaf primordia development (P1-P7). Initially, MaKN1 is expressed ubiquitously throughout primordia (P1-P3); however, as lobes develop, MaKN1 becomes localized to recently emerged lobe primordia, and disappears as lobes develop basipetally. CONCLUSIONS: The pattern of gene expression is indicative of shared developmental processes during early development between shoots, compound leaves, highly lobed simple leaves and unifoliate simple leaves which lack KNOXI expression. These findings are supportive of Arber's less rigid 'partial shoot' theory, which conceptualizes compound leaves as having shoot-like elements.

Diversity of floral visitors to sympatric Lithophragma species differing in floral morphology.

Most coevolving relationships between pairs of species are embedded in a broader multispecific interaction network. The mutualistic interaction between Lithophragma parviflorum (Saxifragaceae) and its pollinating floral parasite Greya politella (Lepidoptera, Prodoxidae) occurs in some communities as a pairwise set apart from most other interactions in those communities. In other communities, however, this pair of species occurs with congeners and with other floral visitors to Lithophragma. We analyzed local and geographic differences in the network formed by interactions between Lithophragma plants and Greya moths in communities containing two Lithophragma species, two Greya species, and floral visitors other than Greya that visit Lithophragma flowers. Our goal was to evaluate if non-Greya visitors were common, if visitor assembly differs between Lithophragma species and populations and if these visitors act as effective pollinators. Sympatric populations of L. heterophyllum and L. parviflorum differ in floral traits that may affect assemblies of floral visitors. Visitation rates by non-Greya floral visitors were low, and the asymptotic number of visitor species was less than 20 species in all populations. Lithophragma species shared some of the visitors, with visitor assemblages differing between sites more for L. heterophyllum than for L. parviflorum. Pollination efficacy experiments showed that most visitors were poor pollinators. Single visits to flowers by this assemblage of species resulted in significantly higher seed set in Lithophragma heterophyllum (30.6 +/- 3.9 SE) than in L. parviflorum (4.7 +/- 3.4 SE). This difference was consistent between sites, suggesting that these visitors provide a better fit to the floral morphology of L. heterophyllum. Overall, none of the non-Greya visitors appears to be either sufficiently common or efficient as a pollinator to impose strong selection on any of these four Lithophragma populations in comparison with Greya, which occurs within almost all populations of these species throughout their geographic ranges.

Replacement of species along altitude gradients: the role of branch architecture.

BACKGROUND AND AIMS: Plant species typical of cold and warm habitats differ in a suite of morpho-physio-phenological traits, although their evolutionary routes have been poorly explored. Here, it is advocated that traits typical of different climate regimes can be largely driven by contrasting branch architectures. This is explored within Saxifraga. First, an investigation was carried out to determine whether series Ceratophyllae (lateral inflorescences) is segregated to lowlands compared with Pentadactylis (terminal inflorescences). Then, two altitudinal vicariants, S. trifurcata (lowland, with lateral inflorescences) and S. canaliculata (highland, with apical inflorescences), were selected. It was hypothesized that apical flowering of S. canaliculata constrains its growth period, bringing with it traits typical of short growth season plants, and conversely for S. trifurcata. METHODS: The hypothesis was tested by measuring plant compactness and organ pre-formation in seven populations of these species along an altitude gradient. KEY RESULTS: Most variables differed among species. Morphological variables at all scales support that the architecture of S. canaliculata generates a more compact habit. A higher number of primordia and earlier inflorescence pre-formation in S. canaliculata indicate that it begins organogenesis earlier. Data on organogenesis suggest that the different timing of inflorescence initiation may be the origin of the contrasting architectures. Within species, shoot compactness increased, and the length of lateral primordia decreased, as altitude increased. All other metrics were similar among locations of the same species at contrasting altitudes. CONCLUSIONS: The hypotheses linking elevational segregation of species, architecture and pheno-morphological traits were validated at broad (gen. Saxifraga) and local (altitudinal vicariants) scales. This supports the initial idea that shoot architecture may to a large extent condition high altitude adaptive syndrome.

Parallel floral adaptations to pollination by fungus gnats within the genus Mitella (Saxifragaceae).

The widespread pattern of parallel flower evolution as an adaptation for particular pollinator agents, known as "pollination syndromes", has long drawn attention from evolutionary biologists. Here, we report parallel evolution of saucer-shaped flowers and an associated unusual pollination system within the lineage Heucherina, a group of saxifragaceous genera. Field observations reveal that 18 of 28 plant species studied are pollinated almost exclusively by fungus gnats (Mycetophilidae). Among the 18 species with a fungus-gnat pollination system, 13 have characteristic saucer-shaped flowers and are pollinated mainly by several unspecialized mycetophilid genera with short mouthparts. We performed phylogenetic analyses using nucleotide sequences of external and internal transcribed spacers of nuclear ribosomal DNA and reconstructed ancestral floral morphologies with an establishment of the model of floral character evolution under a maximum-likelihood framework. Our analysis indicates that there is significant directionality in the evolutionary shifts of floral forms in the Heucherina. The inferred phylogeny further supports four origins of saucer-shaped flowers, which is shared among 14 species that are traditionally classified into the genus Mitella. In addition, our analysis indicates the extensive polyphyly of genus Mitella, as also suggested previously. The results suggest that the flower-visiting fungus gnats have caused convergent selection for the saucer-shaped flower repeatedly evolved within Heucherina.

[Pharmacognostic identification of Rodersia aesculifolia].

OBJECTIVE: To establish pharmacognostical methods of Rodersia aesculifolia. METHODS: Macroscopical, microscopic and physicochemical identification were used to authenticate this crude drug, and the identification characteristics were studied. RESULTS: There were some palea on the rhizoma superior extremity and some white flare dot on transverse section. Vascular bundle formed into interval circularity in rhizoma transverse section, and some small atypia bundle appeared in lateral of core. Xylem of root was tetrarch. A lot of starch grain and acicular cyrstal were observed in parenchyma cell. Brown cell was present as single or several linked. CONCLUSION: These characteristics can be used as identification basis for Rodersia aesulifolia Batal.