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Background and Aims Cress seeds release allelochemicals that over-stimulate the elongation of hypocotyls of neighbouring (potentially competing) seedlings and inhibit their root growth. The hypocotyl promoter is potassium, but the root inhibitor was unidentified; its nature is investigated here. Methods Low-molecular-weight cress-seed exudate (LCSE) from imbibed Lepidium sativum seeds was fractionated by phase partitioning, paper chromatography, high-voltage electrophoresis and gel-permeation chromatography (on Bio-Gel P-2). Fractions, compared with pure potassium salts, were bioassayed for effects on Amaranthus caudatus seedling growth in the dark for 4 days. Key Results The LCSE robustly promoted amaranth hypocotyl elongation and inhibited root growth. The hypocotyl inhibitor was non-volatile, hot acid stable, hydrophilic and resistant to incineration, as expected for K+. The root inhibitor(s) had similar properties but were organic (activity lost on incineration). The root inhibitor(s) remained in the aqueous phase (at pH 2.0, 6.5 and 9.0) when partitioned against butan-1-ol or toluene, and were thus hydrophilic. Activity was diminished after electrophoresis, but the remaining root inhibitors were neutral. They became undetectable after paper chromatography; therefore, they probably comprised multiple compounds, which separated from each other, in part, during fractionation. On gel-permeation chromatography, the root inhibitor co-eluted with hexoses. Conclusions Cress-seed allelochemicals inhibiting root growth are different from the agent (K+) that over-stimulates hypocotyl elongation and the former probably comprise a mixture of small, non-volatile, hydrophilic, organic substances. Abundant components identified chromatographically and by electrophoresis in cress-seed exudate fitting this description include glucose, fructose, sucrose and galacturonic acid. However, none of these sugars co-chromatographed and co-electrophoresed with the root-inhibitory principle of LCSE, and none of them (in pure form at naturally occurring concentrations) inhibited root growth. We conclude that the root-inhibiting allelochemicals of cress-seed exudate remain unidentified. [ABSTRACT FROM AUTHOR]

* Background and aims Cress-seed (Lepidium sativum) exudate exerts an allelochemical effect, promoting excessive hypocotyl elongation and inhibiting root growth in neighbouring Amaranthus caudatus seedlings. We investigated acidic disaccharides present in cress-seed exudate, testing the proposal that the allelochemical is an oligosaccharin--lepidimoic acid (LMA; 4-deoxy-β-L-ihreo-hex-4-enopyranuronosyl-(1→2)-L-rhamnose). * Methods Cress-seed exudate was variously treated [heating, ethanolic precipitation, solvent partitioning, high-voltage paper electrophoresis and gel-permeation chromatography (GPC)], and the products were bioassayed for effects on dark-grown Amaranthus seedlings. Two acidic disaccharides, including LMA, were isolated and characterized by electrophoresis, thin-layer chromatography (TLC) and nuclear magnetic resonance (NMR) spectroscopy, and then bioassayed. * Key Results Cress-seed exudate contained low-Mr, hydrophilic, heat-stable material that strongly promoted Amaranthus hypocotyl elongation and inhibited root growth, but that separated from LMA on electrophoresis and GPC. Cress-seed exudate contained ~250 µM LMA, whose TLC and electrophoretic mobilities, susceptibility to mild acid hydrolysis and NMR spectra are reported. A second acidic disaccharide, present at ~120 µM, was similarly characterized, and shown to be β-D-xylopyranosyl-(1→3)-D-galacturonic acid (Xyl→GalA), a repeat unit of xylogalacturonan. Purified LMA and Xyl→GalA when applied at 360 and 740 mM, respectively, only slightly promoted Amaranthus hypocotyl growth, but equally promoted root growth and thus had no effect on the hypocotyl:root ratio, unlike total cress-seed exudate. * Conclusions LMA is present in cress seeds, probably formed by rhamnogalacturonan lyase action on rhamnoga-lacturonan-I during seed development. Our results contradict the hypothesis that LMA is a cress allelochemical that appreciably perturbs the growth of potentially competing seedlings. Since LMA and Xyl→GalA slightly promoted both hypocotyl and root elongation, their effect could be nutritional. We conclude that rhamnogalacturonan-I and xylogalacturonan (pectin domains) are not sources of oligosaccharins with allelochemical activity, and the biological roles (if any) of the disaccharides derived from them are unknown. The main allelochemical principle in cress-seed exudate remains to be identified. [ABSTRACT FROM AUTHOR]

* Background and Aims Trees invest in both primary (e.g. height) and secondary (e.g. diameter) growth. The trade-off between these investments varies between species and changes with the tree growing environment. To better establish this trade-off, readily available allometric exponents relating height to diameter at breast height (γh,dbh) and stem volume to diameter at breast height (αvdbh) were simultaneously studied. * Methods Allometric exponents αv,dbh and γh,dbh were obtained from 8893 individual tree stem analyses from two broadleaved species (Betula papyrifera, Populus tremuloides) and four conifers (Picea glauca, Picea mariana, Pinus banksiana, Abies balsamea) in the temperate and boreal forests of the province of Quebec, Canada. αvdbh and γh,dbh were related to tree age, stand density index (SDI), and mean temperature (TGS) and total precipitation (PGS) of the growing season. * Key Results αv,jdbh and γh,dbh were found to be invariant with PGS and positively related to SDI and TGS for all species except Pinus banksiana. The parameter values associated with SDI and TGS were of higher value for conifers than for broadleaved species. * Conclusions This suggests that conifers and broadleaved species have different growth patterns. This could be explained by their different mode of development, the conifer species having a stronger apical dominance than broadleaved species. Such results could be further considered in allocation studies to quantify future carbon stocks in managed forests. [ABSTRACT FROM AUTHOR]

Background and Aims: During evolution, plants have acquired and/or lost diverse sugar residues as cell-wall constituents. Of particular interest are primordial cell-wall features that existed, and in some cases abruptly changed, during the momentous step whereby land-plants arose from charophytic algal ancestors., Methods: Polysaccharides were extracted from four charophyte orders [Chlorokybales (Chlorokybus atmophyticus), Klebsormidiales (Klebsormidium fluitans, K. subtile), Charales (Chara vulgaris, Nitella flexilis), Coleochaetales (Coleochaete scutata)] and an early-diverging land-plant (Anthoceros agrestis). 'Pectins' and 'hemicelluloses', operationally defined as extractable in oxalate (100 °C) and 6 m NaOH (37 °C), respectively, were acid- or Driselase-hydrolysed, and the monosaccharides analysed chromatographically. One unusual monosaccharide, 'U', was characterized by (1)H/(13)C-nuclear magnetic resonance spectroscopy and also enzymically., Key Results: 'U' was identified as 3-O-methyl-D-galactose (3-MeGal). All pectins, except in Klebsormidium, contained acid- and Driselase-releasable galacturonate, suggesting homogalacturonan. All pectins, without exception, released rhamnose and galactose on acid hydrolysis; however, only in 'higher' charophytes (Charales, Coleochaetales) and Anthoceros were these sugars also efficiently released by Driselase, suggesting rhamnogalacturonan-I. Pectins of 'higher' charophytes, especially Chara, contained little arabinose, instead possessing 3-MeGal. Anthoceros hemicelluloses were rich in glucose, xylose, galactose and arabinose (suggesting xyloglucan and arabinoxylan), none of which was consistently present in charophyte hemicelluloses., Conclusions: Homogalacturonan is an ancient streptophyte feature, albeit secondarily lost in Klebsormidium. When conquering the land, the first embryophytes already possessed rhamnogalacturonan-I. In contrast, charophyte and land-plant hemicelluloses differ substantially, indicating major changes during terrestrialization. The presence of 3-MeGal in charophytes and lycophytes but not in the 'intervening' bryophytes confirms that cell-wall chemistry changed drastically between major phylogenetic grades., (© The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

• Background and Aims Although it is commonly accepted that root exudation enhances plant--microbial interactions in the rhizosphere, experimental data on the spatial distribution of exudates are scarce. Our hypothesis was that root hairs exude organic substances to enlarge the rhizosphere farther from the root surface. • Methods Barley (Hordeum vulgare 'Pallas' -- wild type) and its root-hairless mutant (brb) were grown in rhizoboxes and labelled with 14CO2. A filter paper was placed on the soil surface to capture, image and quantify root exudates. • Key Results Plants with root hairs allocated more carbon (C) to roots (wild type: 13 %; brb: 8 % of assimilated 14C) and to rhizosheaths (wild type: 1.2 %; brb: 0.2 %), while hairless plants allocated more C to shoots (wild type: 65 %; brb: 75 %). Root hairs increased the radial rhizosphere extension three-fold, from 0.5 to 1.5 mm. Total exudation on filter paper was three times greater for wild type plants compared to the hairless mutant. • Conclusion Root hairs increase exudation and spatial rhizosphere extension, which probably enhance rhizosphere interactions and nutrient cycling in larger soil volumes. Root hairs may therefore be beneficial to plants under nutrient-limiting conditions. The greater C allocation below ground in the presence of root hairs may additionally foster C sequestration. [ABSTRACT FROM AUTHOR]

Background The plant family Cactaceae provides some of the most striking examples of adaptive evolution, expressing undeniably the most spectacular New World radiation of succulent plants distributed across arid and semi-arid regions of the Americas. Cacti are widely regarded for their cultural, economic and ecological value, yet they are also recognized as one of the most threatened and endangered taxonomic groups on the planet. Scope This paper reviews current threats to species of cacti that have distributions in arid to semi-arid subtropical regions. Our review focuses primarily on four global change forces: (1) increases in atmospheric CO2 concentrations; (2) increases in mean annual temperatures and heat waves; (3) increases in the duration, frequency and intensity of droughts; and (4) and increases in competition and wildfire frequency from invasion by non-native species. We provide a broad range of potential priorities and solutions for stemming the extinction risk of cacti species and populations. Conclusions Mitigating ongoing and emerging threats to cacti will require not only strong policy initiatives and international cooperation, but also new and creative approaches to conservation. These approaches include determining species at risk from climate extremes, enhancing habitat quality after disturbance, approaches and opportunities for ex situ conservation and restoration, and the potential use of forensic tools for identifying plants that have been removed illegally from the wild and sold on open markets. [ABSTRACT FROM AUTHOR]

Background In January 1972, Klaus Winter submitted his first paper on crassulacean acid metabolism (CAM) whilst still an undergraduate student in Darmstadt. During the subsequent half-century, he passed his Staatsexamensarbeit, obtained his Dr. rer. nat. summa cum laude and Dr. rer. nat. habil. won a Heinz Maier-Leibnitz Prize and a Heisenberg Fellowship, and has occupied positions in Germany, Australia, the USA and Panama. Now a doyen in CAM circles, and a Senior Staff Scientist at the Smithsonian Tropical Research Institute (STRI), he has published over 300 articles, of which about 44 % are about CAM. Scope I document Winter's career, attempting to place his CAM-related scientific output and evolution in the context of factors that have influenced him as he and his science progressed from the 1970s to the 2020s. [ABSTRACT FROM AUTHOR]

Scope : This paper is a short biographical sketch of my life as a plant ecophysiologist in which serendipity and outstanding collaborators have been key allies. [ABSTRACT FROM AUTHOR]

The study of plant evolution and development in a phylogenetic context has accelerated research advances in both areas over the last decade. The addition of a robust phylogeny for plant taxa based on DNA as well as morphology has given a strong context for this research. Genetics and genomics, including sequencing of many genes, and a better understanding of non-genetic, responsive changes, by plants have increased knowledge of how the different body forms of plants have arisen. Here, I overview the papers in this Special Issue of Annals of Botany on Morphological Adaptation, bringing together a range of papers that link phylogeny and morphology. These lead to models of development and functional adaptation across a range of plant systems, with implications for ecology and ecosystems, as well as development and evolution. [ABSTRACT FROM AUTHOR]

Background Laser scanning technology has opened new horizons for the research of forest dynamics, because it provides a largely automated and non-destructive method to rapidly capture the structure of individual trees and entire forest stands at multiple spatial scales. The structural data themselves or in combination with additional remotely sensed data also provide information on the local physiological state of structures within trees. The capacity of new methods is facilitated by the ongoing development of automated processing tools that are designed to capture information from the point cloud data provided by the remote measurements. Scope Terrestrial laser scanning (TLS), performed from the ground or from unmanned aerial vehicles, in particular, has potential to become a unifying measurement standard for forest research questions, because the equipment is flexible to use in the field and has the capacity to capture branch-level structural information at the forestplot or even forest scale. This issue of Annals of Botany includes selected papers that exemplify the current and potential uses of TLS, such as for examination of crown interactions between trees, growth dynamics of mixed stands, non-destructive characterization of urban trees, and enhancement of ecological and evolutionary models. The papers also present current challenges in the applicability of TLS methods and report recent developments in methods facilitating the use of TLS data for research purposes, including automatic processing chains and quantifying branch and above-ground biomass. In this article, we provide an overview of the current and anticipated future capacity of TLS and related methods in solving questions that utilize measurements and models of forests. Conclusions Due to its measurement speed, TLS provides a method to effortlessly capture large amounts of detailed structural forest information, and consequent proxy data for tree and forest processes, at a far wider spatial scale than is feasible with manual measurements. Issues with measurement precision and occlusion of laser beams before they reach their target structures continue to reduce the accuracy of TLS data, but the limitations are counterweighted by the measurement speed that enables large sample sizes. The currently high time-cost of analysing TLS data, in turn, is likely to decrease through progress in automated processing methods. The developments point towards TLS becoming a new and widely accessible standard tool in forest measurement and modelling. [ABSTRACT FROM AUTHOR]

Background and Aims Previous studies have described the laying down of specific B horizons in south-western Australian ecosystems. This paper presents biomolecular, morphological and physicochemical analyses elucidating the roles of specific woody plant taxa and rhizosphere bacteria in producing these phenomena. Methods Clayey deposits within lateral root systems of eucalypts and appropriate background soil samples were collected aseptically at multiple locations on sand dunes flanking Lake Chillinup. Bacterial communities were profiled using tagged next-generation sequencing (Miseq) of the 16S rRNA gene and assigned to operational taxonomic units. Sedimentation, selective dissolution and X-ray diffraction analyses quantitatively identified clay mineral components. Comparisons were made of pedological features between the above eucalypt systems, giant podzols under proteaceous woodland on sand dunes at the study site of Jandakot and apparently similar systems observed elsewhere in the world. Key Results Bacterial communities in clay pods are highly diverse, resolving into 569 operational taxonomic units dominated by Actinobacteria at 38.0–87.4 % of the total reads. Multivariate statistical analyses of community fingerprints demonstrated substrate specificity. Differently coloured pods on the same host taxon carry distinctive microfloras correlated to diversities and abundances of Actinobacteria, Acidobacteria, Firmicutes and Proteobacteria. A number of these microbes are known to form biominerals, such as phyllosilicates, carbonates and Fe-oxides. A biogenic origin is suggested for the dominant identified mineral precipitates, namely illite and kaolinite. Comparisons of morphogenetic features of B horizons under eucalypts, tree banksias and other vegetation types show remarkably similar developmental trajectories involving pods of precipitation surrounding specialized fine rootlets and their orderly growth to form a continuous B horizon. Conclusions The paper strongly supports the hypothesis that B-horizon development is mediated by highly sophisticated interactions of host plant and rhizosphere organisms in which woody plant taxa govern overall morphogenesis and supply of mineral elements for precipitation, while rhizosphere microorganisms execute biomineralization processes. [ABSTRACT FROM AUTHOR]

This article emphasizes the importance of plant reproduction and pollination in the survival and evolution of plant species. It discusses how the evolution of pollen allowed for more efficient dispersal of male gametes and the development of mutualistic relationships between plants and animal pollinators. The article also highlights the vulnerability of plant-pollinator interactions to human-induced environmental changes. It introduces a focus issue on pollination and floral regulation, which includes research papers on various topics such as the role of heat-shock factors in inducing flowering, the functional significance of enantiostyly in promoting wing pollination, pollinator switching in sage plants, the effects of nitrogen deposition on floral traits, the importance of pollen production in olive trees, and the use of 3D microscopic imaging to study male meiocyte development in wild-rye plants. These papers contribute to our understanding of plant reproduction and pollination and emphasize the need for further research in these areas. [Extracted from the article]

• Background Annals of Botany is a peer-reviewed plant biology journal. It was started in 1887, making it the oldest continuously published plant science title. A previous article [Jackson MB. 2015. One hundred and twenty-five years of the Annals of Botany. Part 1: the first 50 years (1887-1936). Annals of Botany 115: 1-18] summarized events leading to its founding, highlighted the individuals involved and examined the Journal's achievements and management practices over the first 50 years to 1937. This second article covers the next 75 years. • Sources of information The account draws principally on the Journal's own records, minute books, financial accounts, original letters and notes held by the Annals of Botany Company, the Journal's owners and managers. • Content In 1937, its 51st year, the Journal was re-launched as Annals of Botany New Series and its volume numbers were reset to No. I. The present article evaluates the evolution of the New Series up to 2012, Annals of Botany's 125th anniversary year. The period includes a 2-year run-up to World War II, six war years and their immediate aftermath, and then on through increasingly competitive times. The ebb and flow of the Journal's fortunes are set against a roll-call of the often highly distinguished scientists who managed and edited the Journal. The article also examines an internal crisis in the 1980s that radically altered the Journal's organization in ways that were, ultimately, to its benefit. The narrative is set against changes to economic conditions in Great Britain over the period, to the evolving nature and geographical distribution of much experimental plant science and to the digital revolution that, from the late 20th century, transformed the workings of Annals of Botany and of scientific publishing more generally. [ABSTRACT FROM AUTHOR]

* Background The structure and function of plant roots and their interactions with soil are exciting scientific frontiers that will ultimately reveal much about our natural systems, global water and mineral and carbon cycles, and help secure food supplies into the future. This Special Issue presents a collection of papers that address topics at the forefront of our understanding of root biology. * Scope These papers investigate how roots cope with drought, nutrient deficiencies, toxicities and soil compaction as well as the interactions that roots have with soil microorganisms. Roots of model plant species, annual crops and perennial species are studied in short-term experiments through to multi-year trials. Spatial scales range from the gene up to farming systems and nutrient cycling. The diverse, integrated approaches described by these studies encompass root genetics as applied to soil management, as well as documenting the signalling processes occurring between roots and shoots and between roots and soil. * Conclusions This Special Issue on roots presents invited reviews and research papers covering a span of topics ranging from fundamental aspects of anatomy, growth and water uptake to roots in crop and pasture systems. Understanding root structure and function and adaptation to the abiotic and biotic stresses encountered in field conditions is important for sustainable agricultural production and better management of natural systems. [ABSTRACT FROM AUTHOR]

Erratum to: Long-term research reveals potential role of hybrids in climate-change adaptation. I Annals of Botany i doi: 10.1093/aob/mcab085 This paper is a commentary on 'Expansion of the rare I Eucalyptus risdonii i under climate change through hybridisation with a closely related species despite hybrid inferiority'. A commentary on 'Expansion of the rare Eucalyptus risdonii under climate change through hybridisation with a closely related species despite hybrid inferiority'. [Extracted from the article]

This is a correction to: Natalia Ruiz-Vargas, Karolis Ramanauskas, Alexa S Tyszka, Eric C Bretz, May T S Yeo, Roberta J Mason-Gamer, Joseph F Walker, Transcriptome data from silica-preserved leaf tissue reveal gene flow patterns in a Caribbean bromeliad, Annals of Botany, 2024; mcae002, https://doi.org/10.1093/aob/mcae002In the originally published version of this paper, the map in Figure 1b showed the island's elevation instead of the FEEMS results. Figure 1a remains the same.Graph: Figure 1 (Corrected)This error has been corrected in the paper. [Extracted from the article]

Background Polyploidy or whole-genome duplication is now recognized as being present in almost all lineages of higher plants, with multiple rounds of polyploidy occurring in most extant species. The ancient evolutionary events have been identified through genome sequence analysis, while recent hybridization events are found in about half of the world's crops and wild species. Building from this new paradigm for understanding plant evolution, the papers in this Special Issue address questions about polyploidy in ecology, adaptation, reproduction and speciation of wild and cultivated plants from diverse ecosystems. Other papers, including this review, consider genomic aspects of polyploidy. Approaches Discovery of the evolutionary consequences of new, evolutionarily recent and ancient polyploidy requires a range of approaches. Large-scale studies of both single species and whole ecosystems, with hundreds to tens of thousands of individuals, sometimes involving 'garden' or transplant experiments, are important for studying adaptation. Molecular studies of genomes are needed to measure diversity in genotypes, showing ancestors, the nature and number of polyploidy and backcross events that have occurred, and allowing analysis of gene expression and transposable element activation. Speciation events and the impact of reticulate evolution require comprehensive phylogenetic analyses and can be assisted by resynthesis of hybrids. In this Special Issue, we include studies ranging in scope from experimental and genomic, through ecological to more theoretical. Conclusions The success of polyploidy, displacing the diploid ancestors of almost all plants, is well illustrated by the huge angiosperm diversity that is assumed to originate from recurrent polyploidization events. Strikingly, polyploidization often occurred prior to or simultaneously with major evolutionary transitions and adaptive radiation of species, supporting the concept that polyploidy plays a predominant role in bursts of adaptive speciation. Polyploidy results in immediate genetic redundancy and represents, with the emergence of new gene functions, an important source of novelty. Along with recombination, gene mutation, transposon activity and chromosomal rearrangement, polyploidy and whole-genome duplication act as drivers of evolution and divergence in plant behaviour and gene function, enabling diversification, speciation and hence plant evolution. [ABSTRACT FROM AUTHOR]

Background Breeding for advantageous root traits will play a fundamental role in improving the efficiency of water and nutrient acquisition, closing yield gaps, and underpinning the 'Evergreen Revolution' that must match crop production with human demand. Scope This preface provides an overview of a Special Issue of Annals of Botany on 'Root traits benefitting crop production in environments with limited water and nutrient availability'. The first papers in the Special Issue examine how breeding for reduced shoot stature and greater harvest index during the Green Revolution affected root system architecture. It is observed that reduced plant height and root architecture are inherited independently and can be improved simultaneously to increase the acquisition and utilization of carbon, water and mineral nutrients. These insights are followed by papers examining beneficial root traits for resource acquisition in environments with limited water or nutrient availability, such as deep rooting, control of hydraulic conductivity, formation of aerenchyma, proliferation of lateral roots and root hairs, foraging of nutrient-rich patches, manipulation of rhizosphere pH and the exudation of low molecular weight organic solutes. The Special Issue concludes with papers exploring the interactions of plant roots and microorganisms, highlighting the need for plants to control the symbiotic relationships between mycorrhizal fungi and rhizobia to achieve maximal growth, and the roles of plants and microbes in the modification and development of soils. [ABSTRACT FROM AUTHOR]

• Background: Due in great part to their often complex interactions with mycorrhizal fungi, pollinators and host trees, Orchidaceae present particular challenges for conservation. Furthermore, orchids, as potentially the largest family of angiosperms with >26000 species, species complexes and frequent hybrid formation, are complex to catalogue. Following a highlight in 2015, a further seven papers focusing on orchids, their interactions with beneficial organisms, pollinators and mycorrhiza, and other factors relating to their conservation, including threats from human utilization and changing land use, are presented here. • Conclusions: The production of an online flora of all known plants and an assessment of the conservation status of all known plant species as far as possible, to guide conservation action are the first two targets of the Global Strategy for Plant Conservation. Without knowing how many species there are and how they should be circumscribed, neither of these targets is achievable. Orchids are a fascinating subject for fundamental research with rapid species evolution, specific organ structure and development, but they also suffer from high levels of threat. Effective orchid conservation must take account of the beneficial interactions with fungi and pollinators and the potentially detrimental effects of over-collection and changes in land use. [ABSTRACT FROM AUTHOR]

Background Soil salinity, in both natural and managed environments, is highly heterogeneous, and understanding how plants respond to this spatiotemporal heterogeneity is increasingly important for sustainable agriculture in the era of global climate change. While the vast majority of research on crop response to salinity utilizes homogeneous saline conditions, a much smaller, but important, effort has been made in the past decade to understand plant molecular and physiological responses to heterogeneous salinity mainly by using split-root studies. These studies have begun to unravel how plants compensate for water/nutrient deprivation and limit salt stress by optimizing root-foraging in the most favourable parts of the soil. Scope This paper provides an overview of the patterns of salinity heterogeneity in rain-fed and irrigated systems. We then discuss results from split-root studies and the recent progress in understanding the physiological and molecular mechanisms regulating plant responses to heterogeneous root-zone salinity and nutrient conditions. We focus on mechanisms by which plants (salt/nutrient sensing, root-shoot signalling and water uptake) could optimize the use of less-saline patches within the root-zone, thereby enhancing growth under heterogeneous soil salinity conditions. Finally, we place these findings in the context of defining future research priorities, possible irrigation management and crop breeding opportunities to improve productivity from salt-affected lands. [ABSTRACT FROM AUTHOR]

Background and Aims Nitrogen is often regarded as a limiting factor to plant growth in various ecosystems. Understanding how nitrogen drives plant growth has numerous theoretical and practical applications in agriculture and ecology. In 2004, Göran I. Ågren proposed a mechanistic model of plant growth from a biochemical perspective. However, neglecting respiration and assuming stable and balanced growth made the model unrealistic for plants growing in natural conditions. The aim of the present paper is to extend Ågren's model to overcome these limitations. Methods We improved Ågren's model by incorporating the respiratory process and replacing the stable and balanced growth assumption with a three-parameter power function to describe the relationship between nitrogen concentration (N c) and biomass. The new model was evaluated based on published data from three studies on corn (Zea mays) growth. Key Results Remarkably, the mechanistic growth model derived in this study is mathematically equivalent to the classical Richards model, which is the most widely used empirical growth model. The model agrees well with empirical plant growth data. Conclusions Our model provides a mechanistic interpretation of how nitrogen drives plant growth. It is very robust in predicting growth curves and the relationship between N c and relative growth rate. [ABSTRACT FROM AUTHOR]

Background and Aims Foliar water uptake has recently been suggested as a possible mechanism for the restoration of hydraulically dysfunctional xylem vessels. In this paper we used a combination of ecophysiological measurements, X-ray microcomputed tomography and cryo-scanning electron microscopy during a drought treatment to fully evaluate this hypothesis. Key Results Based on an assessment of these methods in beech (Fagus sylvatica L.) seedlings we were able to (1) confirm an increase in the amount of hydraulically redistributed water absorbed by leaves when the soil water potential decreased, and (2) locate this redistributed water in hydraulically active vessels in the stem. However, (3) no embolism repair was observed irrespective of the organ under investigation (i.e. stem, petiole or leaf) or the intensity of drought. Conclusions Our data provide evidence for a hydraulic pathway from the leaf surface to the stem xylem following a water potential gradient, but this pathway exists only in functional vessels and does not play a role in embolism repair for beech. [ABSTRACT FROM AUTHOR]

Background and Aims Some Caryophyllales species accumulate abnormally large shoot sodium (Na) concentrations in non-saline environments. It is not known whether this is a consequence of altered Na partitioning between roots and shoots. This paper tests the hypotheses (1) that Na concentrations in shoots ([Na]shoot) and in roots ([Na]root) are positively correlated among Caryophyllales, and (2) that shoot Na hyperaccumulation is correlated with [Na]shoot/[Na]root quotients. Methods Fifty two genotypes, representing 45 Caryophyllales species and 4 species from other angiosperm orders, were grown hydroponically in a non-saline, complete nutrient solution. Concentrations of Na in shoots and in roots were determined using inductively coupled plasma mass spectrometry (ICP-MS). Key Results Sodium concentrations in shoots and roots were not correlated among Caryophyllales species with normal [Na]shoot, but were positively correlated among Caryophyllales species with abnormally large [Na]shoot. In addition, Caryophyllales species with abnormally large [Na]shoot had greater [Na]shoot/[Na]root than Caryophyllales species with normal [Na]shoot. Conclusions Sodium hyperaccumulators in the Caryophyllales are characterized by abnormally large [Na]shoot, a positive correlation between [Na]shoot and [Na]root, and [Na]shoot/[Na]root quotients greater than unity. [ABSTRACT FROM AUTHOR]

Background and Aims Embryonic sporophytes of the moss Aloina ambigua are inducibly desiccation tolerant (DT). Hardening to DT describes a condition of temporary tolerance to a rapid-drying event conferred by a previous slow-drying event. This paper aimed to determine whether sporophytic embryos of a moss can be hardened to DT, to assess how the rate of desiccation influences the post-rehydration dynamics of recovery, hardening and dehardening, and to determine the minimum rate of drying for embryos and shoots. Methods Embryos were exposed to a range of drying rates using wetted filter paper in enclosed Petri dishes, monitoring relative humidity (RH) inside the dish and equilibrating tissues with 50 % RH. Rehydrated embryos and shoots were subjected to a rapid-drying event at intervals, allowing assessments of recovery, hardening and dehardening times. Key Results The minimum rate of slow drying for embryonic survival was ~3.5 h and for shoots ~9h. Hardening to DT was dependent upon the prior rate of drying. When the rate of drying was extended to 22 h, embryonic hardening was strong (>50 % survival) with survival directly proportional to the post-rehydration interval preceding rapid drying. The recovery time (repair/reassembly) was so short as to be undetectable in embryos and shoots desiccated gradually; however, embryos dried in <3.5 h exhibited a lag time in development of ~4d, consistent with recovery. Dehardening resulted in embryos incapable of surviving a rapid-drying event. Conclusions The ability of moss embryos to harden to DT and the influence of prior rate of drying on the dynamics of hardening are shown for the first time. The minimum rate of drying is introduced as a new metric for assessing ecological DT, defined as the minimum duration at sub-turgor during a drying event in which upon rehydration the plant organ of interest survives relatively undamaged from the desiccating event. [ABSTRACT FROM AUTHOR]

Background and Aims The programmed softening occurring during fruit development requires scission of cell wall polysaccharides, especially pectin. Proposed mechanisms include the action of wall enzymes or hydroxyl radicals. Enzyme activities found in fruit extracts include pectate lyase (PL) and endo-polygalacturonase (EPG), which, in vitro , cleave de-esterified homogalacturonan in mid-chain by β-elimination and hydrolysis, respectively. However, the important biological question of whether PL exhibits action in vivo had not been tested. Methods We developed a method for specifically and sensitively detecting in-vivo PL products, based on Driselase digestion of cell wall polysaccharides and detection of the characteristic unsaturated product of PL action. Key Results In model in-vitro experiments, pectic homogalacturonan that had been partially cleaved by commercial PL was digested to completion with Driselase, releasing an unsaturated disaccharide ('ΔUA–GalA'), taken as diagnostic of PL action. ΔUA–GalA was separated from saturated oligogalacturonides (EPG products) by electrophoresis, then subjected to thin-layer chromatography (TLC), resolving ΔUA–GalA from higher homologues. The ΔUA–GalA was confirmed as 4-deoxy-β- l - threo -hex-4-enopyranuronosyl-(1→4)- d -galacturonic acid by NMR spectroscopy. Driselase digestion of cell walls from ripe fruits of date (Phoenix dactylifera), pear (Pyrus communis), rowan (Sorbus aucuparia) and apple (Malus pumila) yielded ΔUA–GalA, demonstrating that PL had been acting in vivo in these fruits prior to harvest. Date-derived ΔUA–GalA was verified by negative-mode mass spectrometry, including collision-induced dissociation (CID) fragmentation. The ΔUA–GalA:GalA ratio from ripe dates was roughly 1:20 (mol mol–1), indicating that approx. 5 % of the bonds in endogenous homogalacturonan had been cleaved by in-vivo PL action. Conclusions The results provide the first demonstration that PL, previously known from studies of fruit gene expression, proteomic studies and in-vitro enzyme activity, exhibits enzyme action in the walls of soft fruits and may thus be proposed to contribute to fruit softening. [ABSTRACT FROM AUTHOR]

Background and Aims Extant plant groups with a long fossil history are key elements in understanding vascular plant evolution. Horsetails (Equisetum , Equisetaceae) have a nearly continuous fossil record dating back to the Carboniferous, but their phylogenetic and biogeographic patterns are still poorly understood. We use here the most extensive phylogenetic analysis to date as a framework to evaluate their age, biogeography and genome size evolution. Methods DNA sequences of four plastid loci were used to estimate divergence times and investigate the biogeographic history of all extant species of Equisetum. Flow cytometry was used to study genome size evolution against the framework of phylogenetic relationships in Equisetum. Key Results On a well-supported phylogenetic tree including all extant Equisetum species, a molecular clock calibrated with multiple fossils places the node at which the outgroup and Equisetum diverged at 343 Mya (Early Carboniferous), with the first major split among extant species occurring 170 Mya (Middle Jurassic). These dates are older than those reported in some other recent molecular clock studies but are largely in agreement with a timeline established by fossil appearance in the geological record. Representatives of evergreen subgenus Hippochaete have much larger genome sizes than those of deciduous subgenus Equisetum , despite their shared conserved chromosome number. Subgenus Paramochaete has an intermediate genome size and maintains the same number of chromosomes. Conclusions The first divergences among extant members of the genus coincided with the break-up of Pangaea and the resulting more humid, warmer climate. Subsequent tectonic activity most likely involved vicariance events that led to species divergences combined with some more recent, long-distance dispersal events. We hypothesize that differences in genome size between subgenera may be related to the number of sperm flagellae. [ABSTRACT FROM AUTHOR]

Background Investigating the causes and consequences of intraspecific trait variation (ITV) in plants is not novel, as it has long been recognized that such variation shapes biotic and abiotic interactions. While evolutionary and population biology have extensively investigated ITV, only in the last 10 years has interest in ITV surged within community and comparative ecology. Scope Despite this recent interest, still lacking are thorough descriptions of ITV's extent, the spatial and temporal structure of ITV, and stronger connections between ITV and community and ecosystem properties. Our primary aim in this review is to synthesize the recent literature and ask: (1) How extensive is intraspecific variation in traits across scales, and what underlying mechanisms drive this variation? (2) How does this variation impact higher-order ecological processes (e.g. population dynamics, community assembly, invasion, ecosystem productivity)? (3) What are the consequences of ignoring ITV and how can these be mitigated? and (4) What are the most pressing research questions, and how can current practices be modified to suit our research needs? Our secondary aim is to target diverse and underrepresented traits and plant organs, including anatomy, wood, roots, hydraulics, reproduction and secondary chemistry. In addressing these aims, we showcase papers from the Special Issue. Conclusions Plant ITV plays a key role in determining individual and population performance, species interactions, community structure and assembly, and ecosystem properties. Its extent varies widely across species, traits and environments, and it remains difficult to develop a predictive model for ITV that is broadly applicable. Systematically characterizing the sources (e.g. ontogeny, population differences) of ITV will be a vital step forward towards identifying generalities and the underlying mechanisms that shape ITV. While the use of species means to link traits to higher-order processes may be appropriate in many cases, such approaches can obscure potentially meaningful variation. We urge the reporting of individual replicates and population means in online data repositories, a greater consideration of the mechanisms that enhance and constrain ITV's extent, and studies that span sub-disciplines. [ABSTRACT FROM AUTHOR]

Background With up to 200 published contributions, the GreenLab mathematical model of plant growth, developed since 2000 under Sino-French co-operation for agronomic applications, is descended from the structural models developed in the AMAP unit that characterize the development of plants and encompass them in a conceptual mathematical framework. The model also incorporates widely recognized crop model concepts (thermal time, light use efficiency and light interception), adapting them to the level of the individual plant. Scope Such long-term research work calls for an overview at some point. That is the objective of this review paper, which retraces the main history of the model's development and its current status, highlighting three aspects. (1) What are the key features of the GreenLab model? (2) How can the model be a guide for defining relevant measurement strategies and experimental protocols? (3) What kind of applications can such a model address? This last question is answered using case studies as illustrations, and through the Discussion. Conclusions The results obtained over several decades illustrate a key feature of the GreenLab model: owing to its concise mathematical formulation based on the factorization of plant structure, it comes along with dedicated methods and experimental protocols for its parameter estimation, in the deterministic or stochastic cases, at single-plant or population levels. Besides providing a reliable statistical framework, this intense and long-term research effort has provided new insights into the internal trophic regulations of many plant species and new guidelines for genetic improvement or optimization of crop systems. [ABSTRACT FROM AUTHOR]

Background Functional–structural plant models (FSPMs) explore and integrate relationships between a plant's structure and processes that underlie its growth and development. In the last 20 years, scientists interested in functional–structural plant modelling have expanded greatly the range of topics covered and now handle dynamical models of growth and development occurring from the microscopic scale, and involving cell division in plant meristems, to the macroscopic scales of whole plants and plant communities. Scope The FSPM approach occupies a central position in plant science; it is at the crossroads of fundamental questions in systems biology and predictive ecology. This special issue of Annals of Botany features selected papers on critical areas covered by FSPMs and examples of comprehensive models that are used to solve theoretical and applied questions, ranging from developmental biology to plant phenotyping and management of plants for agronomic purposes. Altogether, they offer an opportunity to assess the progress, gaps and bottlenecks along the research path originally foreseen for FSPMs two decades ago. This review also allows discussion of current challenges of FSPMs regarding (1) integration of multidisciplinary knowledge, (2) methods for handling complex models, (3) standards to achieve interoperability and greater genericity and (4) understanding of plant functioning across scales. Conclusions This approach has demonstrated considerable progress, but has yet to reach its full potential in terms of integration and heuristic knowledge production. The research agenda of functional–structural plant modellers in the coming years should place a greater emphasis on explaining robust emergent patterns, and on the causes of possible deviation from it. Modelling such patterns could indeed fuel both generic integration across scales and transdisciplinary transfer. In particular, it could be beneficial to emergent fields of research such as model-assisted phenotyping and predictive ecology in managed ecosystems. [ABSTRACT FROM AUTHOR]

The article focuses on the criticism of the study by researcher Peter Bailey and others on the role of root hairs in anchorage of the plant by Glyn Bengough and others. Topics include their conclusion that epidermal outgrowths do assist in the anchorage of root tips to soil particles during soil penetration, and their mention of two 21st century papers that state that root hairs have an anchorage role, but which don't cite sources supporting that notion of Bailey.

Background Relative growth rate (RGR) has a long history of use in biology. In its logged form, RGR = ln[(M  + Δ M)/ M ], where M is size of the organism at the commencement of the study, and Δ M is new growth over time interval Δ t. It illustrates the general problem of comparing non-independent (confounded) variables, e.g. (X  +  Y) vs. X. Thus, RGR depends on what starting M (X) is used even within the same growth phase. Equally, RGR lacks independence from its derived components, net assimilation rate (NAR) and leaf mass ratio (LMR), as RGR = NAR × LMR, so that they cannot legitimately be compared by standard regression or correlation analysis. Findings The mathematical properties of RGR exemplify the general problem of 'spurious' correlations that compare expressions derived from various combinations of the same component terms X and Y. This is particularly acute when X >> Y , the variance of X or Y is large, or there is little range overlap of X and Y values among datasets being compared. Relationships (direction, curvilinearity) between such confounded variables are essentially predetermined and so should not be reported as if they are a finding of the study. Standardizing by M rather than time does not solve the problem. We propose the inherent growth rate (IGR), lnΔ M /ln M , as a simple, robust alternative to RGR that is independent of M within the same growth phase. Conclusions Although the preferred alternative is to avoid the practice altogether, we discuss cases where comparing expressions with components in common may still have utility. These may provide insights if (1) the regression slope between pairs yields a new variable of biological interest, (2) the statistical significance of the relationship remains supported using suitable methods, such as our specially devised randomization test, or (3) multiple datasets are compared and found to be statistically different. Distinguishing true biological relationships from spurious ones, which arise from comparing non-independent expressions, is essential when dealing with derived variables associated with plant growth analyses. [ABSTRACT FROM AUTHOR]

The article focuses on the essential nutrients the plants need to grow healthy. It states that phosphorus (P) is one of these nutrients the plants need to complete their life cycle. It forecasts the shortage of supply of inorganic compounds or raw materials. It relates that the solution to the problem is the genetically modified (GM)approach to manage the P deficiency.

Background and Aims Terrestrial plant remains in fossilized tree resin are relatively common. However, histology and preservation of plants entombed in Cretaceous ambers remain poorly known. We report an exquisitely preserved conifer leafy axis from 100-million-year-old opaque amber of western France that is assignable to Glenrosa carentonensis Moreau, Néraudeau, Tafforeau & Dépré. The purpose of this paper is to discuss the taphonomy and the use of microtomography for studies of palaeobotanical remains in amber. Methods A leafy axis was examined using propagation phase-contrast X-ray synchrotron microtomography with voxel sizes of 14·9, 1·4, and 0·7 μm. Key Results The conifer leafy axis described is preserved in three dimensions. Despite desiccation of the specimen within the surrounding amber, the cuticle, as well as most of inner tissues, is preserved in three dimensions down to the cellular level. Epidermis, palisade parenchyma, spongy parenchyma, transfusion tracheids and vascular bundles are clearly distinguished. Conclusions Gross morphology and histology of the specimen were revealed using synchrotron microtomography, allowing an unprecedented resolution for the study of soft-bodied plants entombed in amber. The study reveals a peculiar combination of authigenic and duripartic preservation as well as permineralization, and highlights the complexity of taphonomic processes that can occur in amber inclusions. This fossil demonstrates the difficulty of studying amber-preserved plant remains under certain conditions. [ABSTRACT FROM AUTHOR]

• Background and Aims Acropetal root branching is a major process which increases the number of growing tips and distributes their growth potential within the whole root system. • Methods Using a method presented in a recent paper, the defined branching traits were estimated in 140 different species, and the branching patterns of monocots (45 species) and dicots (95 species) were compared. • Key Results It was checked that the method also applied to monocots (not considered in the previous paper), and that all traits could be estimated in each species. Variations of most traits were even larger for monocots than for dicots. Systematic differences appeared between these two groups: monocots tended to have a larger range in apical diameters (stronger heterorhizy), with both finer and thicker roots; the diameters of their lateral roots were also more variable; their roots exerted a stronger dominance over lateral branches. Altogether, species exhibited two main dependencies among their traits that were illustrated using two axes: (1) the 'fineness-density' axis separated the species which develop very fine roots and branch densely, from species without fine roots which space out their branches; and (2) the 'dominance-heterorhizy' axis separated the species according to the range in their apical diameter which was positively correlated to the level of dominance of mother roots over their branches. Both axes and correlations were remarkably similar for monocots and dicots. • Conclusions Beyond the overall typology, this study went on to validate the phenotyping method in Natura, and showed its potential to characterize the differences in groups of species. [ABSTRACT FROM AUTHOR]

Background and Aims Improving crops requires better linking of traits and metabolic processes to whole plant performance. In this paper, we present CN-Wheat, a comprehensive and mechanistic model of carbon (C) and nitrogen (N) metabolism within wheat culms after anthesis. Methods The culm is described by modules that represent the roots, photosynthetic organs and grains. Each of them includes structural, storage and mobile materials. Fluxes of C and N among modules occur through a common pool and through transpiration flow. Metabolite variations are represented by differential equations that depend on the physiological processes occurring in each module. A challenging aspect of CN-Wheat lies in the regulation of these processes by metabolite concentrations and the environment perceived by organs. Key Results CN-Wheat simulates the distribution of C and N into wheat culms in relation to photosynthesis, N uptake, metabolite turnover, root exudation and tissue death. Regulation of physiological activities by local concentrations of metabolites appears to be a valuable feature for understanding how the behaviour of the whole plant can emerge from local rules. Conclusions The originality of CN-Wheat is that it proposes an integrated view of plant functioning based on a mechanistic approach. The formalization of each process can be further refined in the future as knowledge progresses. This approach is expected to strengthen our capacity to understand plant responses to their environment and investigate plant traits adapted to changes in agronomical practices or environmental conditions. A companion paper will evaluate the model. [ABSTRACT FROM AUTHOR]

Background: Green infrastructure is a strategic network of green spaces designed to deliver ecosystem services to human communities. Green infrastructure is a convenient concept for urban policy makers, but the term is used too generically and with limited understanding of the relative values or benefits of different types of green space and how these complement one another. At a finer scale/more practical level, little consideration is given to the composition of the plant communities, yet this is what ultimately defines the extent of service provision. This paper calls for greater attention to be paid to urban plantings with respect to ecosystem service delivery and for plant science to engage more fully in identifying those plants that promote various services. Scope: Many urban plantings are designed based on aesthetics alone, with limited thought on how plant choice/ composition provides other ecosystem services. Research is beginning to demonstrate, however, that landscape plants provide a range of important services, such as helping mitigate floods and alleviating heat islands, but that not all species are equally effective. The paper reviews a number of important services and demonstrates how genotype choice radically affects service delivery. Conclusions: Although research is in its infancy, data are being generated that relate plant traits to specific services, thereby helping identify genotypes that optimize service delivery. The urban environment, however, will become exceedingly bland if future planting is simply restricted to monocultures of a few 'functional' genotypes. Therefore, further information is required on how to design plant communities where the plants identified (1) provide more than a single benefit (multifunctionality), (B) complement each other in maximizing the range of benefits that can be delivered in one location, and (3) continue to maintain public acceptance through diversity. The identification/ development of functional landscape plants is an exciting and potentially high-impact arena for plant science. [ABSTRACT FROM AUTHOR]

Background and aims Rhamnogalacturonan-II (RG-II) is a domain of primary cell-wall pectin. Pairs of RG-II domains are covalently cross-linked via borate diester bridges, necessary for normal cell growth. Interpreting the precise mechanism and roles of boron bridging is difficult because there are conflicting hypotheses as to whether bridging occurs mainly within the Golgi system, concurrently with secretion or within the cell wall. We therefore explored the kinetics of RG-II bridging. Methods Cell-suspension cultures of Rosa and arabidopsis were pulse-radiolabelled with [14C]glucose, then the boron bridging status of newly synthesized [14C]RG-II domains was tracked by polyacrylamide gel electrophoresis of endo-polygalacturonase digests. Key results Optimal culture ages for 14C-labelling were ~5 and ~1 d in Rosa and arabidopsis respectively. De-novo [14C]polysaccharide production occurred for the first ~90 min; thereafter the radiolabelled molecules were tracked as they 'aged' in the wall. Monomeric and (boron-bridged) dimeric [14C]RG-II domains appeared simultaneously, both being detectable within 4 min of [14C]glucose feeding, i.e. well before the secretion of newly synthesized [14C]polysaccharides into the apoplast at ~15–20 min. The [14C]dimer : [14C]monomer ratio of RG-II remained approximately constant from 4 to 120 min, indicating that boron bridging was occurring within the Golgi system during polysaccharide biosynthesis. However, [14C]dimers increased slightly over the following 15 h, indicating that limited boron bridging was continuing after secretion. Conclusions The results show where in the cell (and thus when in the 'career' of an RG-II domain) boron bridging occurs, helping to define the possible biological roles of RG-II dimerization and the probable localization of boron-donating glycoproteins or glycolipids. [ABSTRACT FROM AUTHOR]

Background and Aims Miscanthus , a C4 perennial grass native to East Asia, is a promising biomass crop. Miscanthus sacchariflorus has a broad geographic range, is used to produce paper in China and is one of the parents (along with Miscanthus sinensis) of the important biomass species Miscanthus × giganteus. The largest study of M. sacchariflorus population genetics to date is reported here. Methods Collections included 764 individuals across East Asia. Samples were genotyped with 34 605 single nucleotide polymorphisms (SNPs) derived from restriction site-associated DNA sequencing (RAD-seq) and ten plastid microsatellites, and were subjected to ploidy analysis by flow cytometry. Key Results Six major genetic groups within M. sacchariflorus were identified using SNP data: three diploid groups, comprising Yangtze (M. sacchariflorus ssp. lutarioriparius), N China and Korea/NE China/Russia; and three tetraploid groups, comprising N China/Korea/Russia, S Japan and N Japan. Miscanthus sacchariflorus ssp. lutarioriparius was derived from the N China group, with a substantial bottleneck. Japanese and mainland tetraploids originated from independent polyploidization events. Hybrids between diploid M. sacchariflorus and M. sinensis were identified in Korea, but without introgression into either parent species. In contrast, tetraploid M. sacchariflorus in southern Japan and Korea exhibited substantial hybridization and introgression with local diploid M. sinensis. Conclusions Genetic data indicated that the land now under the Yellow Sea was a centre of diversity for M. sacchariflorus during the last glacial maximum, followed by a series of migrations as the climate became warmer and wetter. Overall, M. sacchariflorus has greater genetic diversity than M. sinensis , suggesting that breeding and selection within M. sacchariflorus will be important for the development of improved M. × giganteus. Ornamental M. sacchariflorus genotypes in Europe and North America represent a very narrow portion of the species' genetic diversity, and thus do not well represent the species as a whole. [ABSTRACT FROM AUTHOR]

Background The Annals of Botany is a peer-reviewed scientific journal publishing papers on a wide range of topics in plant biology. It first appeared in 1887, making it the oldest continuously published botanical title. The present article gives a historical account of events leading to the founding of the Journal and of its development over the first 50 years.Sources of Information Much of the content is drawn from the Journal’s own records and from extensive Minutes, financial accounts, personal letters and notes relating to the Annals of Botany that were repatriated from University College, University of London in 1999. Documents held at the Royal Botanic Gardens, Kew and at the Oxford University Press Museum were also consulted.Content Emphasis is placed on the individuals who instigated, edited and managed the Annals of Botany up to 1937, especially the nine founding members of the Journal and the background that brought them together and motivated them to start the Annals of Botany. A falling out between two of the founders in 1899 is highlighted since not only did this threaten the Journal’s future but also gives much insight into the personalities of those most closely involved in the Journal during its formative years. The article also examines the way the Journal was funded and how it dealt with its publisher (the University of Oxford’s Clarendon Press), turned itself into a registered company (the Annals of Botany Company) and coped with the travails of the First World War, currency inflation and the Great Depression. Plans to re-start the Journal as a New Series, beginning in 1937, are discussed in the context of the competition the Annals of Botany then faced from younger journals. [ABSTRACT FROM PUBLISHER]

Background and Aims Fleshy structures that promote biotic dispersal by ingestion have evolved many times in seed plants. Within the yew family Taxaceae sensu lato (six genera, including Cephalotaxus), it remains controversial whether the characteristic fleshy structure surrounding the seed is interpreted as a novel outgrowth of the base of the ovule (i.e. an aril) or a fleshy seed coat that is entirely derived from the integument (i.e. a sarcotesta). This paper presents a detailed study of both wild-type and teratological seed cones of Pseudotaxus chienii, including morphology, anatomy and ontogeny. Methods Wild-type and teratological seed cones were investigated with the classical paraffin technique and subsequent astrablue/safranin staining and scanning electron microscopy. Key Results The wild-type seed cone of Pseudotaxus possesses a fleshy white aril that is cup-like and not entirely fused to the seed. In the teratological seed cones investigated, the aril was bilobed and consisted of two free halves. In both wild-type and teratological cones, the aril was initiated as two lateral primordia in a transverse plane, but in wild-type cones the two primordia became extended into a ring primordium, which grew apically, leading to the cup-like shape. The teratological seed cones lacked a ring primordium and the two lateral aril lobes remained free throughout their entire ontogeny, alternating with the scale-like leaves inserted below them on the same branch; in some cases, these leaves also became fleshy. Conclusions Based on the ontogeny and arrangement of the two fleshy aril lobes in the teratological seed cones of Pseudotaxus, we suggest that the typical aril of Taxaceae could be readily interpreted as a fused pair of strongly swollen leaves rather than a modified integument. Our investigations of the cup-like aril of Pseudotaxus demonstrate a similarity not only with other Taxaceae but also with relatively distantly related conifers such as Phyllocladus (Podocarpaceae). [ABSTRACT FROM AUTHOR]

Background and Aims Helicocytic stomata are characterized by an inward spiral of mesogenous cells surrounding a central stomatal pore. They represent a relatively rare feature that occurs in some drought-tolerant angiosperm species. In some Begonia species with thick leaves, the stomata are not only helicocytic but also clustered into groups that are spaced apart by at least one cell. This paper presents a detailed ontogenetic study of this characteristic non-contiguous stomatal patterning in a developmental and phylogenetic context. Methods Light microscopy and both scanning and transmission electron microscopy were used to examine stomatal development in several species of Begonia. Published reports of stomatal development in Begonia and other angiosperms were reviewed to provide a comprehensive discussion of the evolution of stomatal patterning. Key Results Helicocytic stomata develop from meristemoids that undergo a series of oriented asymmetric divisions to produce a spiral of mesogene stomatal lineage ground cells (SLGCs) surrounding a stoma. A clear developmental similarity between anisocytic and helicocytic stomata is positively correlated with the number of iterations of amplifying divisions that result in SLGCs. Stomatal clusters develop from asymmetric divisions in neighbouring SLGCs. Within each cluster, non-contiguous spacing of meristemoids is maintained by asymmetric divisions oriented away from each developing meristemoid. Conclusions Formation of non-contiguous stomatal clusters in Begonia relies on two primary developmental factors in the epidermis: an inwardly spiralling series of amplifying divisions that result in helicocytic stomata, and the development of a variable number of meristemoids from neighbouring SLGCs within each cluster. Optimization of these features on an angiosperm phylogeny indicates that the occurrence of amplifying divisions could be pre-adaptive for these factors. Both factors have been thoroughly studied in terms of developmental genetics in Arabidopsis, suggesting gene orthologues that could be implicated in Begonia stomatal patterning. [ABSTRACT FROM AUTHOR]

Background Interest in tree form assessments using the terrestrial laser scanner (TLS) has increased in recent years. Yet many existing methods are limited to small-sized trees, principally due to noise and occlusion phenomena. In this paper, a novel voxel-based program that is dedicated to the analyses of large tree structures is presented. The method is based on the assumption that architectural trait variations (i.e. branching angle, bifurcation ratio, biomass allocation, etc.) influence the way a tree explores space. This method uses the concept of space exploration that considers a voxel as a portion of space explored by the tree. Once the TLS scene is voxelized, the program provides tools that extract qualitative (geometrical) and quantitative (volumetric) metrics. These tools measure (1) voxel dispersion in three dimensions (3-D), (2) projections of the voxel cloud in 2-D and (3) multi-temporal changes within a single tree crown. Scope To test algorithm capabilities of measuring larger tree architectural traits, two application studies were conducted using point clouds that were either generated by a tree growth simulation model, thereby allowing algorithm application in a perfectly controlled environment, or acquired in the field with a TLS device. The space exploration concept makes it possible to take advantage of the volumetric nature of voxels to compensate for occlusion. The hypothesis that large-sized voxels can be used to reduce occlusion in the original point cloud was tested, as well as the consequences of voxel size on quantification of tree volume and on precision of derived metrics. Conclusions Results show that space exploration is well adapted to highlight architectural differences among trees. They also suggest that large-sized voxels are efficient for occlusion compensation at the expense of metrics precision in some cases. The best resolution to choose depending on the research objectives and quality of the TLS scan is discussed. [ABSTRACT FROM AUTHOR]

Background and Aims In Central Europe Hypericum perforatum and Hypericum maculatum show significant hybridization and introgression as a consequence of Pleistocene range fluctuations, and their gene pools are merging on higher ploidy levels. This paper discusses whether polyploid hybrid gene pools are trapped in the ecological climatic niche space of their diploid ancestors, and tests the idea of geographical parthenogenesis. Methods DNA sequence information of nuclear ribosomal DNA and plastid loci, ploidy level estimates and ecological niche modelling are used to characterize the various diploid and polyploid gene pools and unravel spatio-temporal patterns of gene flow among them. Key Results On the diploid level, the three gene pools are clearly distinct between and within species of H. perforatum (two gene pools) and H. maculatum, and their divergence dates back to the first half of the Pleistocene. All polyploids in Central Europe show high levels of past and contemporary gene flow between all three gene pools. The correlation of genetic and geographical distances breaks down if the latter is larger than 250 km, indicating recent and ongoing gene flow. The two species are ecologically differentiated, but in particular hybrids among all three gene pools do not show significant niche differences compared to their parental gene pools, except for some combinations with H. maculatum. Conclusions Inter- and intraspecific gene flow between inter- and intra-species gene pools is limited on the diploid level, and the geographical distribution of the diploids largely reflects Pleistocene evolutionary history. Secondary contact promoted hybridization and introgression on the polyploid level, enabling offspring to escape the diploid gene pools. However, the hybrid polyploids do not show significant niche differences compared to their diploid progenitors. It is concluded that the observed absence of niche divergence has precluded further differentiation and geographical partitioning of new polyploid lineages being effectively separated from the parental lines. The predominantly apomictic reproducing polyploids are trapped in the polyploid gene pool and the ecological climatic niche space of their diploid ancestors. [ABSTRACT FROM AUTHOR]

• Background and Aims Imbibed cress (Lepidium sativum L.) seeds exude 'allelochemicals' that promote excessive hypocotyl elongation and inhibit root growth in neighbouring competitors, e.g. amaranth (Amaranthus caudatus L.) seedlings. The major hypocotyl promoter has recently been shown not to be the previously suggested acidic disaccharide, lepidimoic acid (LMA), a fragment of the pectic polysaccharide domain rhamnogalacturonan-I. The nature of the hypocotyl promoter has now been re-assessed. • Methods Low-molecular weight cress-seed exudate (LCSE) was fractionated by high-voltage electrophoresis, and components with different charge:mass ratios were tested for effects on dark-grown amaranth seedlings. Further samples of LCSE were size-fractionated by gel permeation chromatography, and active fractions were analysed electrophoretically. • Key Results The LCSE strongly promoted amaranth hypocotyl elongation. The active principle was hydrophilic and, unlike LMA, stable to hot acid. After electrophoresis at pH 6.5, the only fractions that strongly promoted hypocotyl elongation were those with a very high positive charge:mass ratio, migrating towards the cathode 3-4 times faster than glucosamine. Among numerous naturally occurring cations tested, the only one with such a high mobility was potassium. K+ was present in LCSE at approx. 4 mM, and pure KCl (1-10 mM) strongly promoted amaranth hypocotyl elongation. No other cation tested (including Naþ, spermidine and putrescine) had this effect. The peak of bioactivity from a gel permeation chromatography column exactly coincided with the peak of K+. • Conclusions The major 'allelopathic' substance present in cress-seed exudate that stimulates hypocotyl elongation in neighbouring seedlings is the inorganic cation, K+, not the oligosaccharin LMA. [ABSTRACT FROM AUTHOR]