Opposite Phyllotaxy Research Articles

Pharmacognostic, physicochemical and phytochemical profiles of Euclea divinorum (Ebenaceae)

Background: Euclea divinorum, belonging to the family Ebeneceae, has extensive traditional medicinal use in Africa. However, it lacks sufficient published data on its pharmacognostic, physicochemical, and phytochemical properties. Aims and Objectives: Thus, this study aimed at comprehensively evaluating the pharmacognostic, physicochemical, and phytochemical properties of E. divinorum using established techniques. Materials and Methods: The evaluation included assessing organoleptic properties, macroscopy, and microscopy of leaves, stems, and roots. Various physicochemical parameters, such as loss on drying and extractive values via hot and cold maceration, were determined. Phytochemical screening was also conducted on root aqueous extracts. Results and Conclusion: Results revealed specific characteristics of E. divinorum leaves, including light green coloration, distinct odor, and bitterness. Macroscopic examination highlighted opposite phyllotaxy, simple leaf types with lamina length range of 71.09 - 93.89 mm and a width range of 6.05 - 17.59 mm, obtuse leaf apexes, cuneate leaf bases, entire leaf margins, and smooth leaf surfaces. Venation displayed a reticulate pattern, with the midrib prominently visible on the lower surface. Microscopic analysis of the lower leaf epidermis showed an average of stomatal density of 3.75±0.67, epidermal density of 35.75±2.16 and stomatal index of 10.47±1.11. Microscopic examination of the leaf lamina across the midrib revealed cortical parenchymal cells containing calcium oxalate crystals, lignified xylem, and non-lignified phloem. Stem cross-sections displayed single-layered cells comprising the epidermis, secondary phloem, secondary xylem, and pith. Similar structures were observed in root cross-sections. The plant's moisture content was found to be 44.8±1.962%, with water and alcohol-soluble extractive values of 7.27±0.17 and 1.13±0.05 g/100g, respectively, through cold maceration, and 14.77±0.28 and 11.43±0.39 g/100g, respectively through hot maceration. The total ash content was measured at 3.03± 0.103%. Phytochemical screening detected various compounds, with anthraquinone glycosides, coumarine glycosides, saponin glycosides, flavonoids, proteins, and tannins being abundant. Alkaloids, cardiac glycosides, and steroids were absent. This research contributes to standardizing E. divinorum, aiding in its identification, preventing adulteration, and ensuring therapeutic efficacy.

Arlenea delicata gen. et sp. nov., a new ephedroid plant from the Early Cretaceous Crato Formation, Araripe Basin, Northeast Brazil

Ephedroid macrofossils have been widely documented in Cretaceous deposits, including numerous from the Lower Cretaceous Yixian Formation of NE China. However, few ephedroid macrofossils have been reported from South America. Herein, we describe a new plant of the family Ephedraceae, Arlenea delicata gen. et sp. nov., from the Lower Cretaceous Crato Formation of the Araripe Basin, Northeast Brazil, based on the vegetative and reproductive structures. It has the typical morphological characteristics of ephedroid plants, including fertile reproductive branches, opposite phyllotaxy, terminal female cones, a sympodial branching system, longitudinally striated internodes, and swollen nodes. Our new finding is unusual in having inner chlamydosperms subtended by two pairs of bracts, reproductive units connected to branches through swollen receptacles and a smooth seed surface. This new ephedroid taxon from the Crato Formation increases our understanding of plant diversity of this group during the Early Cretaceous. Furthermore, the general morphology (fleshy bracts and enlarged receptacles) of this new fossil discovery indicates that seeds of this plant may have been dispersed by animals such as pterosaurs (mainly the Tapejaridae) and birds (Enantiornithes and Ornituromorpha). If true, this would explain the cosmopolitan distribution of Ephedraceae in the Lower Cretaceous.

A New Gnetalean Macrofossil from the Mid-Jurassic Daohugou Formation.

Macrofossil evidence has demonstrated a first radiation of gnetophytes in the Early Cretaceous. However, the origin of the diversity of gnetophytes remains ambiguous because gnetalean macrofossils have rarely been reported from pre-Cretaceous strata. Here, we report a new putative gnetalean macrofossil reproductive shoot which possesses opposite phyllotaxy, long linear leaves more or less decurrent and having a prominent midvein and pedicled ovoid-ellipsoid and longitudinally striated chlamydosperms. Our new fossil is different from other known gnetalean macrofossils in the linear-lanceolate leaves with a midvein and pedicled chlamydosperms. As a result, we describe this new macrofossil reproductive shoot as new to science, i.e., Daohugoucladus sinensis gen. et sp. nov. Our new macrofossil displays additional morphological characters distinct from other known Mesozoic and modern gnetalean species and provides additional evidence of the origin and early evolution of female reproductive organs of gnetophytes.

Effects of phyllotaxy on variation and inner relationships of leaflet traits in compound-leaved plants.

To understand the distribution pattern of leaflet traits in compound-leaved along with phyllotaxy, we selected three compound-leaved trees with opposite phyllotaxy in Xiaoxing' an Mountains, Fraxinus mandshurica, Phellodendron amurense, Juglans mandshurica, as the research objects. We measured leaf thickness, leaf area, specific leaf area, leaf dry matter content, palisade tissue thickness, spongy tissue thickness, ratio of palisade tissue thickness to spongy tissue thickness, and carbon content, nitrogen content, phosphorus content of leaflets at different phyllotaxy positions. We analyzed the variation of leaflet traits with phyllotaxy and the influence of phyllotaxy on the inner relationships between leaflet traits. The results showed that the variation of leaflet area, leaflet dry matter content, spongy tissue thickness and ratio of palisade tissue thickness to spongy tissue thickness with the increase of phyllotaxy were mainly divided into three types: increase, decrease, first increase and then decrease. Leaflet thickness, specific leaflet area, palisade tissue thickness, as well as nutrient contents did not change with phyllotaxy. Within compound leaves of three species, the variation coefficients and plasticity index of leaflet thickness, leaflet area, specific leaflet area, leaflet dry matter content, palisade tissue thickness, spongy tissue thickness, ratio of palisade tissue thickness to spongy tissue thickness ranged from 6.1% to 28.6% and from 0.14 to 0.70, respectively. Phyllotaxy had a significant effect on the bivariate correlation between leaflet traits. Specific leaflet area and leaflet dry natter content were negatively correlated in different phyllotaxy positions of F. mandshurica and J. mandshurica. Leaflet nitrogen content and phosphorus content showed a positive correlation in different phyllotaxy positions of F. mandshurica and P. amurense. The first and secondary leaflets (the first leaflets farthest from the base of the petiole) of J. mandshurica showed a conservative strategy, while the seventh and eighth leaflets showed an acquisition strategy. Leaflets of F. mandshurica and P. amurense did not show different ecological strategies.

Morphology of Hoya megalaster Warb. Ex K. Schumann & Lauterb and Hoya pachyphylla Warb. Ex K. Schumann & Lauterb (Apocynaceae) from New Guinea, Indonesia

New Guinea is one the mega-diverse regions of the world and a host to 6% of the world’s biodiversity. Recently, land clearing and forest fragmentation associated with rapid economic growth have become growing threats to biodiversity in New Guinea. One of the several taxa of plants that is affected due to the rapid destruction of its known host plants is the genus Hoya. We describe the vegetative and reproductive morphology of two species of Hoya that are found in the primary forest of Papua in Ubiyau Village, a remote area in West Papua, Indonesia: Hoya megalaster and H. pachyphylla. Both species are perennial climbing epiphytes with opposite phyllotaxy, and short-lived cymes that are positively geotropic. The two species differ in leaf morphology. Hoya megalaster has a thin lamina, while the leaves of H. pachyphylla are succulent. We provide a list of characters that can potentially be used for future morphometric and phylogenetic studies on these two species.

Taxonomic revision of Sageretia (Rhamnaceae) from China I: identities of S. lucida, S. thea var. cordiformis and S. yunlongensis, with the description of a new species S. ellipsoidea

A taxonomic revision of Sageretia lucida, S. thea var. cordiformis and S. yunlongensis in China is presented. Sageretia lucida is revised in terms of morphological characters (habit, branchlet color, phyllotaxis and rachis length), distribution, habitat, and phenology; S. thea var. cordiformis is raised to S. cordiformis; and S. yunlongensis is excluded from the genus Sageretia and reduced to the synonym of Rhamnus nigricans. Furthermore, a new species, S. ellipsoidea, is erected based on the paratype collections of S. lucida. The new species morphologically differs from S. lucida in having reddish brown branchlets, opposite or subopposite phyllotaxis, shorter rachises, and flowering in spring or early summer. S. ellipsoidea is factually closest to S. hamosa as they share similar woody-vine habit and larger fruit size, and fruiting in winter, whereas the former can be easily recognized based on its smaller leaf blades, fewer lateral veins, shorter rachises, and ellipsoidal or elliptic-ovoid fruits.

Taxonomic Characteristics and Phytochemical Constituents of Asystasiagangetica (L.) T. Anderson, a Member of Acanthaceae

This study examined the taxonomic characteristics of Asystasiagangetica; a perennial herb characterized by its trailing to erect habit and as a result, roots from the nodes. It is glabrous and grows up to 80±20 cm. There are simple leaves with petioles which are ovate in shape with opposite phyllotaxy and margins are even to slightly serrated, measuring up to 7±2 cm in length and 3±1 cm in width. The inflorescence is one-sided raceme with purplish-blue tubular flowers which is pentamerous. The fruits are dry dehiscent capsule up to 2±0.5 cm in length. The epidermal studies revealed presence of simple elongated to conical shaped multicellular trichomes and cyclocytic stomata which are amphistomatic in nature, though very scanty in adaxial foliar region. Anatomical study showcased a single layer in the epidermis. The hypodermis consists of 2 to 3 layers of collenchyma, the general cortex and pith is made of parenchyma and cuts across mid-ribs, petioles, stems, nodes and roots, occurring in similar locations except that the number of layers of cells are not the same and vascular bundle is open type. The phytochemical study revealed that the following secondary metabolites are present: alkaloids, saponins and cardiac glycosides while steroidal aglycones, not observed. This information here would assist for further delimitation of the species.

Influence of Mycosphaerella and Teratosphaeria leaf diseases on chemical composition of essential oils of Eucalyptus globulus and effect of these essential oils on ascospores germination.

In a first step, essential oils were extracted from Eucalyptus globulus leaves, healthy and with symptoms and signs of Mycosphaerella leaf disease (MLD) and Teratosphaeria leaf disease (TLD), in two leaf stages. Stage 1: sessile, oval leaves covered by a waxy layer of a bluish colour, with opposite phyllotaxis, inserted along stems of quadrangular section. Stage 2: narrow and sickle leaves with a greyish green surface, mainly on the abaxial surface, inserted in alternating pairs along rounded stems. The essential oils were extracted by hydrodistillation and were analyzed by gas chromatography coupled with mass spectrometry. Chemical composition data and percentages of essential oil constituents were submitted to cluster analysis and principal component analysis. In a second step, under in vitro conditions, was evaluated the germination of Teratosphaeria nubilosa (one of the causal agents of TLD) ascospores in contact with the four types of essential oils extracted. The evaluations were performed at 24, 48 and 72h after the experiments were assembled. The present study made it possible to distinguish and identify the chemical composition of essential oils from the eucalypt leaves used, and allowed 1,8-cineole to be identified as the major component for the essential oils investigated. The contact between essential oils and T. nubilosa spores allowed to prove the inhibition of the ascospores germination, being more efficient for the essential oils extracted from materials with the disease, which presented high amounts of 1,8-cineole.

<p><strong>A new species of <em>Nordenstamia</em> (Compositae, Senecioneae) from central Peru</strong></p>

Nordenstamia valenzuelae sp. nov. is described from the Pui Pui Protection Forest in central Peru. It is a shrub characterized by opposite leaves (upper ones sessile), adaxial leaf surfaces and young stem parts covered by short-stipitate, basic T-shaped, golden-yellow trichomes, and densely white lanate abaxial leaf surfaces. The new species is compared with the morphologically closest taxa and useful characters for their proper identification are provided. A dichotomous key including the Nordenstamia species with consistently opposite phyllotaxy is also presented.

Parallelism in the Development of Life Forms of Species of the Genus Kudrjaschevia (Lamiaceae): Ontogenesis and Architectural Analysis

This study is aimed at studying the herb life forms of closely related narrowly localized endemic species of the genus Kudrjaschevia in Central Asia. A detailed description of life forms will make it possible to identify the morphological rearrangements of plants associated with the adaptation of species to certain ecological conditions. Our results will expand our understanding of the main directions in the evolution of morphs, which has practically not been studied in plants of the Central Asian flora. In the process of somatic evolution, individuals of this group have adapted to various specific habitats: rocks (K. nadinae, K. grubovii, and K. pojarkoviae), mountain screes (K. allotricha), and rocky outcrops of mountain slopes (K. korshinskyi). Using an architectural approach to describing plants, we show that various ecotopic and ecological–coenotic conditions do not affect the nature of the development of life forms of related taxa. Parallelism in the development of life forms in the studied species is manifested in the passage of the same phases of morphogenesis (primary shoot, main axis, and primary bush (clone)) and in the preservation of a monocentic biomorph. In the ontogeny in individuals of closely related species, a similar reiteration of axes is formed. Each axis is characterized as annually dying branching/nonbranching with radial symmetry, having opposite phyllotaxis, the apical meristem of which is realized in inflorescence. The long-term basis of plants in all representatives of Kudrjaschevia is built as a result of the sympodial sequential articulation of the short basal parts of the axes (residues) according to the monochasial/dichasial types. Despite the difference in the aerial parts of the studied rock (K. nadinae, K. grubovii, and K. pojarkoviae) and mountain-slope species (K. allotricha and K. korshinskyi), the shoot formation and the common long-term basis of the individuals are the same. The diversity of the aerial parts of the axes reflects the adaptation of plants to specific ecological conditions, while maintaining a genetically fixed, general development program.

Pharmacognostic evaluation ofCarapa guianensisAubl. leaves: A medicinal plant native from Brazilian Amazon

Background: Carapa guianensis Aubl., known as crabwood, has been used in folk medicine as anti-inflammatory, wound healing, and for the treatment of flu and colds. Objective: The present study aimed to establish the pharmacognostic features of C. guianensis leaves. Materials and Methods: The leaves were investigated according to the World Health Organization guideline on the pharmacognostic specification, which comprised macroscopic and microscopic assessment, phytochemical screening, and physicochemical characterization of the leaves, besides the microscopic analysis of the powder. Results: Leaves were characterized as a compound, coriaceous with elliptic shape, entire margin, acuminate apex, obtuse base, and opposite phyllotaxis. The epidermis has straight periclinal and anticlinal walls. Calcium oxalate crystals were observed in druses, anomocytic stomata just on a lower side (hypostomatic), and dorsiventral mesophyll. Phytochemical screening revealed the presence of flavonoids, saponins, triterpenes, and steroids in the crude extract. The values of the physicochemical parameters such as total ash, acid-insoluble ash, and loss on drying are 7.16%, 1.03% and 7.93%, respectively; the ethanol and water-soluble extractive values are 19.47% and 15.97%, respectively. Conclusions: The information obtained with botanical, physicochemical, and phytochemical studies could be used to identify C. guianensis and to certify the authenticity of commercial samples.

The arrangement of lateral veins along the midvein of leaves is not related to leaf phyllotaxis

Positions of leaves along a stem usually adhere to a genetically determined, species-specific pattern known as a leaf phyllotaxis. We investigated whether the arrangement of lateral secondary veins along primary midveins adhered to a species-specific pattern that resembled an alternate or opposite phyllotaxis. We analyzed the venation of temperate dicotyledonous species from different taxonomic groups and chose 18 woody and 12 herbaceous species that have reticulated leaf venation. The arrangement of the lateral veins was neither alternate nor opposite for any of the species. Lateral vein arrangements were instead mixtures of symmetric and asymmetric patterns. Our results show that lateral vein arrangements are related neither to stem-level leaf phyllotaxis (alternate vs. opposite) nor to life form (woody vs. herbaceous). Our results are therefore generally consistent with the canalization hypothesis that the locations of lateral veins are not completely specified genetically prior to leaf formation.

Herbal textual research on Chinese medicine "Huangjing" (Polygonati Rhizoma)and some enlightenments

To clarify the change and development of the original plants， medicinal organs， traditional functions， resource distribution of "Huangjing"(Polygonati Rhizome)， a traditional Chinese medicine， we investigated Polygonatum species on the ancient Chinese herbal texts. The name of "Nüwei" was first carried out in the book of Sheng Nong's Herbal Classic. Its effects included two aspects： one was similar to "Weirui"(Polygonati Odorati Rhizome， "Yuzhu")， that was tonifying， nourishing one's vitality， removing wind and dampness， settling five organs， making body lightness， keeping longevity and not being hungry; the second was alike to "Huangjing" recorded in the book of Ming Yi Bie Lu(Appendant Records of Famous Physicians). Specifically， "Weirui" possesses the therapeutic effect of "Nüwei"， while "Huangjing" possesses the tonic effect of " Nüwei". Thereafter， the following ancient Chinese herbal texts kept those two names and function records. Accordingly， we hold the point of view that "Huangjing" was first carried out in the book of Sheng Nong's Herbal Classic in the synonym of "Nüwei". "Yuzhu" included the "Huangjing" in ancient herbal text before Qing Dynasty， that was further confirmed by the research on change and development of the original plants. The identification between "Yuzhu" and "Huangjing" was based on the shape of rhizome and size before early Tang Dynasty. The shape was a key character and used up to now， but size was not reasonable. The opposite phyllotaxy was an important character of authentic "Huangjing" from Tang to Qing Dynasty. The seedling of Polygonatum sibiricum and P. kingianum， the adult plant of P. cyrtonema with alternate leaves were misused as "Yuzhu"("Nüwei" and "Weirui") at that time. Therefore， both "Yuzhu" and "Huangjing" should be used as key words during the search of ancient prescriptions and development of new drugs and health foods. The leaves， flowers， fruits and seedlings could be used as food or medicine other than the rhizomes in ancient China， but they haven't been developed in modern times. The culture of "Huangjing" had a long history starting with Tang Dynasty， which was recorded in Tang poetry. Then in Ming Dynasty， the culture method was described in Compendium of Materia Medica， that was cutting the rhizomes into 2 feet， planting sparsely(they would be grown densely in the next year)， or sowing the seeds. The harvesting and processing were first recorded in Ming Yi Bie Lu： "harvest the roots in February， dry in the shade". Then the processing method was changed to "steaming and drying in the sun， repeatedly for nine times" in Shi Liao Ben Cao(Dietetic Materia Medica) and "harvesting in August as well" in Ben Cao Tu Jing(Commentaries on the Illustrations). No breakthrough has been taken in the breeding of cultivars and key cultivation technologies yet. As to the geo-authentic habitats， Mount Songshan and Maoshan were firstly recorded as the best producing areas of "Huangjing" in Ben Cao Tu Jing. But Maoshan， Jiangsu province and Mount Songshan， Henan province， are not main producing areas in modern China. Consequently， the plantation plan of Polygonati Rhizome needs further study.

Triple plagiotropic branch in coffee: a new promising mutant?

Abstract Coffee tree is a shrub with dimorphic branches. The orthotropic stem grows vertically with two near-horizontal plagiotropic branches, per node, in opposite phyllotaxy. The consecutive nodes of the orthotropic stem are organized in parastichies. We report here mutant plants of Coffea arabica with triple plagiotropic branch, resulted from the whorled phyllotaxy of the orthotropic stem. In mutant plants three plagiotropic branches in the same node are separated by angles of approximately 120o, while in normal plants two plagiotropic branches in the same node are separated by angles of approximately 180o. In mutant plants the angles of the parastichies increase approximately 50o clockwise between consecutive nodes, while in normal plants the angles increase approximately 87o. The plant architecture is changed. The triple plagiotropic branch is a putative mutant with potential to be explored in coffee breeding programs. The hypotheses for the origin of the mutation and the research perspectives are discussed.

Transcriptome analysis reveals critical genes and key pathways involved in early phyllotaxy development in maize

Integrated networks of gene expression, hormonal signaling and metabolite sensing regulate phyllotaxy pattern development. In this study, we characterized differentially expressed genes (DEGs) between maize plants with alternate and opposite phyllotaxies. Gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses showed that 2432 DEGs were involved in biological processes, molecular functions, cellular components and many pathways. Importantly, we identified 19 DEGs related to plant hormone signal transduction. Additionally, we identified four main alternative splicing types: skipped exons, retained introns, alternative 5′-splice sites, and alternative 3′-splice sites, which exhibited different characteristics in the alternate and opposite phyllotaxy libraries. The reliability of the sequencing data was verified through using quantitative real-time reverse transcription PCR analysis of the 19 genes: 15 were validated to play a role in phytohormone signal transduction pathways. Taken together, our data provide new insight into the mechanisms of phyllotaxy pattern development, and will increase our understanding of how relative changes in gene expression determine alternate/opposite phyllotaxy in maize.

Parallel evolution of leaf morphology in gnetophytes

In the present paper, an ephedroid macrofossil species from the Early Cretaceous Yixian Formation of western Liaoning of China is described as new to science: Ephedra multinervia Yang et Lin, sp. nov. This species has typical ephedroid morphology, e.g. the dichasial branching shoot system, swollen nodes, internodes having many fine longitudinal striations and opposite phyllotaxy. Ephedra multinervia has strap-shaped leaves with multiple dichotomizing veins and reduced female cones with a single pair of fertile bracts forming a cupule enclosing two inner seeds. Ephedra multinervia is similar to Ephedra archaeorhytidosperma Yang et al. and Ephedra hongtaoi Wang et Zheng in its reduced bi-ovulate female cone, but differs from the latter two species by the lengthy strap-like leaves bearing multiple parallel veins and its sessile female cones. A new evolutionary hypothesis of the gnetophytes is proposed based on a synthesis of reproductive morphology of macrofossils from the Early Cretaceous and modern representatives. A Chengia-like precursor might have given rise to the Gnetum-Welwitschia clade by diversification of leaf morphology and female reproductive organs. According to this new explanation, the Welwitschia-like strap-like leaves with multiple parallel veins in E. multinervia result from convergence.

Effect of temperature on endogenous hormone levels and opposite phyllotaxy in maize leaf primordial.

Newly identified maize (Zea mays) mutants with opposite leaf phyllotaxy are important in the study of the maize crop. Previous studies have revealed the developmental mechanism of opposite phyllotaxy on the physiological, cellular, and molecular levels. However, there have been few reports regarding the effects of changes in endogenous hormone levels in maize leaf primordia under different conditions. We conducted field studies to examine the influence of different environmental factors on leaf primordia differentiation. Our results indicated that compared with other major environmental factors, temperature was significantly positively correlated with the ratio of maize plants with opposite phyllotaxy. We examined endogenous hormone levels in maize at different temperatures using an enzyme-linked immunosorbent assay. The results showed that the ratio of maize plants with opposite phyllotaxy was mainly influenced by the cytokinin/auxin ratio. In addition, at the same temperature, the ratio of cytokinin/auxin in maize with opposite phyllotaxy was significantly higher than that near isogenic lines with alternate phyllotaxy.

Elucidating the determination of the rosette galls induced by Pisphondylia brasiliensis Couri and Maia 1992 (Cecidomyiidae) on Guapira opposita (Nyctaginaceae)

The modulation of plant development has been the focus of research on insect galls because galling insects induce distinct shapes to acquire the same necessities, shelter and food. Due to the variety of gall morphotypes, it can be assumed that the key processes for their development rely on plant cells’ morphogenetical potentialities. In the present study we investigated the rosette bud galls induced by Pisphondylia brasiliensis on Guapira opposita to check whether two morphogenetical pathways – the shortening of the internodes and the over differentiation of axillary buds – are independent or whether they are concomitant events towards the morphogenesis of the galls. Biometrical measures were made to test whether the final size of the galls is correlated with the number of inducers per gall. We noted that two patterns of activity were observed in gall meristems: the first differentiated pairs of leaves with opposite phyllotaxy, and the other differentiated new buds at the base of each leafy projection, with the development of sequential leafy projections, in a disorganised phyllotaxy. This second pattern repeated until gall maturation, when a master cambium, typical of the Nyctaginaceae, differentiated in larger galls. The two morphogenetical pathways occurred concomitantly, leading to the overproduction of leafy projections. Cell responses at gall development site produce mechanical protection to P. brasiliensis individuals. The larger galls have the higher number of inducers, and the coalescence of galls allows an increase in gall size by precociously triggering the master cambium activity, a developmental peculiarity of G. opposita uncommon for Cecidomyiidae galls.

Angiosperm Clades in the Potomac Group: What Have We Learned since 1977?

Abstract In their 1977 study on Potomac Group angiosperms, Hickey and Doyle made only broad comparisons with living taxa. Newer data, especially discoveries of fossil flowers in the Potomac and coeval deposits and increasingly robust molecular phylogenies of living angiosperms, allow more precise phylogenetic placement of fossils. Hickey and Doyle compared most early Potomac leaves (Aptian—early Albian) with “magnoliids,” a paraphyletic group as then defined, but several clades can now be recognized. Leaves and dispersed cuticles share epidermal features with woody members of the basal ANITA grade, and in some cases crown group Austrobaileyales, whose presence is confirmed by flowers called Anacostia. Aptian—Albian flowers (Monetianthus, Carpestella) and whole plants (Pluricarpellatia) are nested in crown group Nymphaeales; Potomac reniform leaves could belong to this clade. Several Potomac leaves have chloranthoid teeth, venation, and opposite phyllotaxis consistent with Chloranthaceae, while Aptian to C...

Change of shoot architecture during juvenile-to-adult phase transition in soybean

Juvenile-to-adult phase change is an indispensable event which guarantees a successful life cycle. Phase change has been studied in maize, Arabidopsis and rice, but is mostly unknown in other species. Soybean/Fabaceae plants undergo drastic changes of shoot architecture at the early vegetative stage including phyllotactic change and leaf type alteration from simple to compound. These characteristics make soybean/Fabaceae plants an interesting taxon for investigating vegetative phase change. Following the expansion of two cotyledons, two simple leaves simultaneously emerge in opposite phyllotaxy. The phyllotaxy of the third and fourth leaves is not fixed; both opposite and distichous phyllotaxis are observed within the same population. Leaves were compound from the third leaf. But the third leaf was rarely simple. Morphological and quantitative changes in early vegetative phase were recognized in leaf size, leaf shape, number of trichomes, stipule size and shape, and shoot meristem shape. Two microRNA genes, miR156 and miR172, are known to be associated with vegetative phase change. Examination of the expression level revealed that miR156 expression was high in the first two leaves and subsequently down-regulated, and that of miR172 showed the inverse expression pattern. These expression patterns coincided with the case of other species. Taken all data together, the first and second leaves represent juvenile phase, the fifth and upper leaves adult phase, and the third and fourth leaves intermediate stage. Further investigation of soybean phase change would give fruitful understandings on plant development.