Search

This book is a compendium of information on plants (and some micro‐organisms) that are, or could be, useful to humans. Some idea of its vast scope can be gained from the list of chapter headings: Plant collecting, taxonomy and nomenclature; Environmental considerations; Plant conservation; Ecophysiology and allied disciplines; Plant breeding and propagation; Marketing of crops and crop products; Human and animal nutrition; Human food and food additives; Feed for livestock; Food for bees and other desirable invertebrates; Timber and wood products; Fuel; Vegetable fibres; Phytochemicals; Human and veterinary medicinal plants; Plant toxins and their applications; Useful ferns, bryophytes, fungi, bacteria and viruses; Useful algae; Environmental uses; and Social uses. In the last chapter ‘At the start of the 21st century’, the book strays into other territories, including the ethics of genetically modified crops. The author does not tell us who this book is written for, and it is difficult to work this out. The last decade has seen a range of specialist books treating many of the chapter topics at the level needed by advanced undergraduates, graduates and professionals; the text here is, necessarily, superficial, descriptive and lacking in analysis. On the other hand, some of the important issues of today in economic botany, such as genetic diversity/resources, intellectual property rights and the use of molecular biological approaches in investigations of phylogenetic relationships, receive little attention. Because the author extends himself beyond his own fields of expertise, there are places in the book where the information is quite misleading. For example, in a rather eccentric chapter on ecophysiology, there is confusion around ‘adaptive and hereditary characters’ and between ‘tolerance and resistance’, none of these terms being clearly defined. Gibberellins are listed as auxins, and other growth substances, such as cytokinins, are not mentioned. Similar comments could be made about other chapters. Careful reading of the text reveals an unsatisfactory standard of proof reading: ‘Puztal’ for Puztai, ‘lycine’ for lysine. The book is nearly all words, with few interpretative figures or tables. There is, however, a set of very comprehensive indexes. This, then, is a mountain of fascinating information for plant scientists, culled during a long career in economic botany: on brown spot disease of rice in the Bengal famine of 1943; the glucomannans used as emulsifiers in food and drink in Japan; the screw pressing of oilseeds; the dye Saxon Green associated with Robin Hood and Sherwood Forest; plant toxins as arrow poisons; and the use of gorse on May Day in Ireland and Wales to ward off witches and fairies from the house. One disappointment is in the discussion of the differing uses of the term ‘marmalade’ in the UK and France: in Dundee, the true home of orange marmalade, it has long been assumed that the recipe was brought from France by Mary, Queen of Scots, and that its etymology refers to her seasickness on the way over. At a cost of £140, this must be one of the last compendia of its type. Much of the information can now be accessed from the world wide web, free of charge, but I will continue to have fun dipping into this book for some time.

Summary. The whole group of islands possesses certain characteristics common to all truly oceanic islands, and some of those which are merely the relics of vanished continents. In the first place, there is the absence of indigenous mammals, and more noticeably of bats, of freshwater fish, and amphibians. Again, the number of indigenous species, both of plants and animals, is very small, while the number of individuals is very large. The insects are small and dull in colour, and but few of the plants have showy flowers, white and yellow being prevailing colours. A considerable proportion of the indigenous plants are shrubby or arboreous, as in many other oceanic islands; but arboreous or even shrubby Composits do not exist, indigenous species of the group being rare in the islands.

Project Co-ordinators: Dr. Jose Alfonso Gómez Calero (Instituto de Agricultura Sostenible (IAS-CISC), Dr. Weifeng Xu (Fujian Agriculture and Forest University, FAFU)., [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., E.B.L., T.C., I.C.D., P.B. and N.B. thank the University of Western Australia for funding the workshop. I.C.D. thanks the European Union (Project 773903 – SHui) for supporting ongoing work on split-root plants. N.B. was a recipient of the Marie Curie Fellowship funded by the European Union (grant 700001).

Background Woody plants (trees and shrubs) play an important role in terrestrial ecosystems, but their size and longevity make them difficult subjects for traditional experiments. In the last 20 years functional–structural plant models (FSPMs) have evolved: they consider the interplay between plant modular structure, the immediate environment and internal functioning. However, computational constraints and data deficiency have long been limiting factors in a broader application of FSPMs, particularly at the scale of forest communities. Recently, terrestrial laser scanning (TLS), has emerged as an invaluable tool for capturing the 3-D structure of forest communities, thus opening up exciting opportunities to explore and predict forest dynamics with FSPMs. Scope The potential synergies between TLS-derived data and FSPMs have yet to be fully explored. Here, we summarize recent developments in FSPM and TLS research, with a specific focus on woody plants. We then evaluate the emerging opportunities for applying FSPMs in an ecological and evolutionary context, in light of TLS-derived data, with particular consideration of the challenges posed by scaling up from individual trees to whole forests. Finally, we propose guidelines for incorporating TLS data into the FSPM workflow to encourage overlap of practice amongst researchers. Conclusions We conclude that TLS is a feasible tool to help shift FSPMs from an individual-level modelling technique to a community-level one. The ability to scan multiple trees, of multiple species, in a short amount of time, is paramount to gathering the detailed structural information required for parameterizing FSPMs for forest communities. Conventional techniques, such as repeated manual forest surveys, have their limitations in explaining the driving mechanisms behind observed patterns in 3-D forest structure and dynamics. Therefore, other techniques are valuable to explore how forests might respond to environmental change. A robust synthesis between TLS and FSPMs provides the opportunity to virtually explore the spatial and temporal dynamics of forest communities.

Background and Aims In water-limited landscapes, some plants build structures that enable them to survive with minimal water (drought resistance). Instead of making structures that allow survival through times of water limitation, annual plants may invoke a drought escape strategy where they complete growth and reproduction when water is available. Drought escape and resistance each require a unique combination of traits and therefore plants are likely to have a suite of trait values that are consistent with a single drought response strategy. In environments where conditions are variable, plants may additionally evolve phenotypically plastic trait responses to water availability. Invasive annual species commonly occur in arid and semi-arid environments and many will be subject to reduced water availability associated with climate change. Assessing intraspecific trait variation across environmental gradients is a valuable tool for understanding how invasive plants establish and persist in arid environments. Methods In this study, we used a common garden experiment with two levels of water availability to determine how traits related to carbon assimilation, water use, biomass allocation and flowering phenology vary in California wild radish populations across an aridity gradient. Key Results We found that populations from arid environments have rapid flowering and increased allocation to root biomass, traits associated with both drought escape and tolerance. Early flowering was associated with higher leaf nitrogen concentration and lower leaf mass per area, traits associated with high resource acquisition. While trait values varied across low- and high-water treatments, these shifts were consistent across populations, indicating no differential plasticity across the aridity gradient. Conclusions While previous studies have suggested that drought escape and drought resistance are mutually exclusive drought response strategies, our findings suggest that invasive annuals may employ both strategies to succeed in novel semi-arid environments. As many regions are expected to become more arid in the future, investigations of intraspecific trait variation within low water environments help to inform our understanding of potential evolutionary responses to increased aridity in invasive species.

Centro de Investigación Forestal (CIFOR), In a range of plant species, the distribution of individual mean fecundity is skewed and dominated by a few highly fecund individuals. Larger plants produce greater seed crops, but the exact nature of the relationship between size and reproductive patterns is poorly understood. This is especially clear in plants that reproduce by exhibiting synchronized quasi-periodic variation in fruit production, a process called masting., The study was supported by the Polish National Science Centre (2017/24/C/NZ8/00151), the Polish State Committee for Scientific Research (6 P04G 045 21, 3 P04G 111 25), the Polish Ministry of Science and Higher Education (N304 362938), the US National Science Foundation (DEB 165511, DEB-02-40963, DEB-05-15756, DEB-10-20889, DBI-9978807, DEB-0642594, DEB-1556707), the Wilkes University Fenner Endowment, USDA/NIFA grant 2017-03807, the Hatch Act (225165) through the USDA National Institute of Food and Agriculture, PROPINEA (CC-16-095, AGL-2017-83828-C2), FORASSEMBLY (CGL2015-70558-P), BEEMED (SGR913) and a Marsden Fund grant (UOC1401)., 9 Pág.

Rhizobia improve legume N nutrition, and modulate other aspects of host nutrition and development. Symbiont impact on host resource allocation and root distribution, important for soil resource acquisition, is discussed., Legumes form symbioses with rhizobia to fix N2 in root nodules to supplement their nitrogen (N) requirements. Many studies have shown how symbioses affect the shoot, but far less is understood about how they modify root development and root system architecture (RSA). RSA is the distribution of roots in space and over time. RSA reflects host resource allocation into below-ground organs and patterns of host resource foraging underpinning its resource acquisition capacity. Recent studies have revealed a more comprehensive relationship between hosts and symbionts: the latter can affect host resource acquisition for phosphate and iron, and the symbiont’s production of plant growth regulators can enhance host resource flux and abundance. We review the current understanding of the effects of rhizobia–legume symbioses on legume root systems. We focus on resource acquisition and allocation within the host to conceptualize the effect of symbioses on RSA, and highlight opportunities for new directions of research.

We conducted a comprehensive analysis of the functional traits of leaves (leaflets) of cycads. The aim of this study was to clarify the functional divergence between the earlier origin Cycadaceae and the later differentiated Zamiaceae, and the differences in trait associations between cycads and angiosperms.We selected 20 Cycadaceae species and 21 Zamiaceae species from the same cycad garden in South China, and measured their leaf structure, economic traits, mechanical resistance (Fp) and leaf water potential at the turgor loss point (πtlp). In addition, we compiled a dataset of geographical distribution along with climatic variables for these cycad species, and some leaf traits of tropical-sub-tropical angiosperm woody species from the literature for comparison.The results showed significantly contrasting leaf trait syndromes between the two families, with Zamiaceae species exhibiting thicker leaves, higher carbon investments and greater Fp than Cycadaceae species. Leaf thickness (LT) and πtlp were correlated with mean climatic variables in their native distribution ranges, indicating their evolutionary adaptation to environmental conditions. Compared with the leaves of angiosperms, the cycad leaves were thicker and tougher, and more tolerant to desiccation. Greater Fp was associated with a higher structural investment in both angiosperms and cycads; however, cycads showed lower Fp at a given leaf mass per area or LT than angiosperms. Enhancement of Fp led to more negative πtlp in angiosperms, but the opposite trend was observed in cycads.Our results reveal that variations in leaf traits of cycads are mainly influenced by taxonomy and the environment of their native range. We also demonstrate similar leaf functional associations in terms of economics, but different relationships with regard to mechanics and drought tolerance between cycads and angiosperms. This study expands our understanding of the ecological strategies and likely responses of cycads to future climate change.

A close relationship of the three Old World taenitidoid genera Austrogramme, Syngramma and Taenitis was traditionally suggested on the basis of morphology, and later gained further support from molecular phylogenetic analyses. However, due to insufficient sampling, the monophyly and intrageneric and interspecific relationships of these genera are still largely untested, and the systematic value of diagnostic morphological characteristics is unclear. In this study, we generated a molecular phylogenetic tree with 18 species representing nearly half of the known species diversity for this group. In addition to macromorphological characteristics, we also observed microscopic characteristics, including soral paraphyses and spores. Our results confirm the monophyly of the three genera and their delimitating characteristics. We found that most of the previously proposed sections are not monophyletic, and their diagnostic characteristics are homoplastic. We propose new hypotheses concerning both intergeneric and interspecific hybridization and provide new taxonomic insights that are critical in understanding the diversity of the group.

Climate change and habitat loss have been identified as the main causes of species extinction. Forest regeneration and protected areas are essential to buffer climate change impacts and to ensure quality habitats for threatened species. We assessed the current and future environmental suitability for the maned sloth, Bradypus torquatus, under both future climate and forest restoration scenarios, using ecological niche modeling. We compared environmental suitability for two Evolutionarily Significant Units (ESUnorth and ESUsouth) using two climate change scenarios for 2070, and three potential forest regeneration scenarios. Likewise, we evaluated the protection degree of the suitable areas resulting from the models, according to Brazilian law: PA—Protected Areas; PPA—Permanent Protection Areas (environmentally sensitive areas in private properties); and LR—Legal Reserves (natural vegetation areas in private properties). Finally, we calculated the deficit of PPA and LR in each ESU, considering the current forest cover. Forest regeneration might mitigate the deleterious effects of climate change by maintaining and increasing environmental suitability in future scenarios. The ESUnorth contains more suitable areas (21,570 km²) than the ESUsouth (12,386 km²), with an increase in all future scenarios (up to 45,648 km² of new suitable areas), while ESUsouth might have a significant decrease (up to 7,546 km² less). Suitable areas are mostly unprotected (ESUnorth—65.5% and ESUsouth—58.3%). Therefore, PPA and PA can maintain only a small portion of current and future suitable areas. Both ESUs present a high deficit of PPA and LR, highlighting the necessity to act in the recovery of these areas to accomplish a large-scale restoration, mitigate climate change effects, and achieve, at least, a minimum forested area to safeguard the species. Notwithstanding, a long-term conservation of B. torquatus will benefit from forest regeneration besides those minimum requirements, allied to the protection of forest areas. Atlantic Forest, climate change, conservation, forest regeneration, landscape ecology, Pilosa, Xenarthra Natural forest regeneration on anthropogenic landscapes could overcome climate change effects on the endangered maned sloth (Bradypus torquatus, Illiger 1811)

Diatoms are one of the most successful group of photosynthetic eukaryotes in the contemporary ocean. They are ubiquitously distributed and are the most abundant primary producers in polar waters. Equally remarkable is their ability to tolerate iron deprivation and respond to periodic iron fertilization. Despite their relatively large cell sizes, diatoms tolerate iron limitation and frequently dominate iron-stimulated phytoplankton blooms, both natural and artificial. Here, we review the main iron use strategies of diatoms, including their ability to assimilate and store a range of iron sources, and the adaptations of their photosynthetic machinery and architecture to iron deprivation. Our synthesis relies on published literature and is complemented by a search of 82 diatom transcriptomes, including information collected from seven representatives of the most abundant diatom genera in the world’s oceans., Diatoms are responsible for an estimated fifth of the total carbon fixation on Earth. Here we review their relationship with a key micronutrient in a changing ocean: iron.

The light-harvesting phycobilisome complex is an important component of photosynthesis in cyanobacteria and red algae. Phycobilisomes are composed of phycobiliproteins, including the blue phycobiliprotein phycocyanin, that are considered high-value products with applications in several industries. Remarkably, several cyanobacteria and red algal species retain the capacity to harvest light and photosynthesise under highly selective environments such as hot springs, and flourish in extremes of pH and elevated temperatures. These thermophilic organisms produce thermostable phycobiliproteins, which have superior qualities much needed for wider adoption of these natural pigment–proteins in the food, textile, and other industries. Here we review the available literature on the thermostability of phycobilisome components from thermophilic species and discuss how a better appreciation of phycobiliproteins from extreme environments will benefit our fundamental understanding of photosynthetic adaptation and could provide a sustainable resource for several industrial processes.

BackgroundCarnivorous plants are an ecological group of approx. 810 vascular species which capture and digest animal prey, absorb prey-derived nutrients and utilize them to enhance their growth and development. Extant carnivorous plants have evolved in at least ten independent lineages, and their adaptive traits represent an example of structural and functional convergence. Plant carnivory is a result of complex adaptations to mostly nutrient-poor, wet and sunny habitats when the benefits of carnivory exceed the costs. With a boost in interest and extensive research in recent years, many aspects of these adaptations have been clarified (at least partly), but many remain unknown.ScopeWe provide some of the most recent insights into substantial ecophysiological, biochemical and evolutional particulars of plant carnivory from the functional viewpoint. We focus on those processes and traits in carnivorous plants associated with their ecological characterization, mineral nutrition, cost–benefit relationships, functioning of digestive enzymes and regulation of the hunting cycle in traps. We elucidate mechanisms by which uptake of prey-derived nutrients leads to stimulation of photosynthesis and root nutrient uptake.ConclusionsUtilization of prey-derived mineral (mainly N and P) and organic nutrients is highly beneficial for plants and increases the photosynthetic rate in leaves as a prerequisite for faster plant growth. Whole-genome and tandem gene duplications brought gene material for diversification into carnivorous functions and enabled recruitment of defence-related genes. Possible mechanisms for the evolution of digestive enzymes are summarized, and a comprehensive picture on the biochemistry and regulation of prey decomposition and prey-derived nutrient uptake is provided.

Background and Aims Mycorrhizal fungi are a critical component of the ecological niche of most plants and can potentially constrain their geographical range. Unlike other types of mycorrhizal fungi, the distributions of orchid mycorrhizal fungi (OMF) at large spatial scales are not well understood. Here, we investigate the distribution and diversity of Ceratobasidium OMF in orchids and soils across the Australian continent. Methods We sampled 217 Ceratobasidium isolates from 111 orchid species across southern Australia and combined these with 311 Ceratobasidium sequences from GenBank. To estimate the taxonomic diversity of Ceratobasidium associating with orchids, phylogenetic analysis of the ITS sequence locus was undertaken. Sequence data from the continent-wide Australian Microbiome Initiative were used to determine the geographical range of operational taxonomic units (OTUs) detected in orchids, with the distribution and climatic correlates of the two most frequently detected OTUs modelled using MaxEnt. Key Results We identified 23 Ceratobasidium OTUs associating with Australian orchids, primarily from the orchid genera Pterostylis, Prasophyllum, Rhizanthella and Sarcochilus. OTUs isolated from orchids were closely related to, but distinct from, known pathogenic fungi. Data from soils and orchids revealed that ten of these OTUs occur on both east and west sides of the continent, while 13 OTUs were recorded at three locations or fewer. MaxEnt models suggested that the distributions of two widespread OTUs are correlated with temperature and soil moisture of the wettest quarter and far exceeded the distributions of their host orchid species. Conclusions Ceratobasidium OMF with cross-continental distributions are common in Australian soils and frequently have geographical ranges that exceed that of their host orchid species, suggesting these fungi are not limiting the distributions of their host orchids at large spatial scales. Most OTUs were distributed within southern Australia, although several OTUs had distributions extending into central and northern parts of the continent, illustrating their tolerance of an extraordinarily wide range of environmental conditions.

Understanding host use by psyllids (Hemiptera: Psylloidea) benefits from comparative studies of behavior on host and nonhost plant species. While most psyllid species develop on one or a few closely related plant species, some species are generalized enough to develop on species across plant families. We used electropenetography (EPG) technology to compare probing activities of an oligophagous psyllid (Bactericera cockerelli (Šulc)) and a host-specialized psyllid (Bactericera maculipennis) on two species of Solanaceae (potato, Solanum tuberosum L. and matrimony vine, Lycium barbarum L.) and two species of Convolvulaceae (field bindweed, Convolvulus arvensis L. and sweet potato, Ipomoea batatas). Bactericera cockerelli develops on all four species, albeit with longer development times on Convolvulaceae. Bactericera maculipennis develops only on Convolvulaceae. Bactericera cockerelli fed readily from phloem of all four species, but the likelihood of entering phloem and duration of time in phloem was reduced on suboptimal hosts (Convolvulaceae) relative to behavior on Solanaceae. We observed instances of cycling between bouts of phloem salivation and ingestion in assays of optimal (Solanaceae) hosts not observed on Convolvulaceae. The Convolvulaceae-specialized B. maculipennis (Crawford) failed to feed from phloem of nonhosts (Solanaceae). Both psyllid species readily ingested from xylem of all plant species, irrespective of host status. Our finding that phloem feeding by B. maculipennis did not occur on potato has implications for understanding epidemiology of phloem-limited psyllid-vectored plant pathogens. Our results also showed that EPG assays detect subtle variation in probing activities that assist in understanding host use by psyllids.

Made available in DSpace on 2022-05-01T08:45:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-09-01 The integration of phylogenetic methods and species distribution can really help in the investigation of biogeographic patterns and to fill gaps in evolutionary ecology. Here we investigated how the vascular flora of the Brazilian ancient Cipó Mountains, an alleged OCBIL (old, climatic buffered infertile landscape) with a high diversity of species and endemism, evolved across that harsh archipelago-like system and altitudinal gradient. We used a node-based analysis of species distributions that follows the concepts of over- and underrepresentation and takes into account the relationship between sister clades, to yield two very statistically tractable metrics: the geographical node divergence and specific over-representation score. We collected and identified plant species along an elevational gradient ranging from 800 to 1400 m a.s.l. We also collected environmental variables such as elevation and soil properties. We found three allopatric nodes, which revealed the major biogeographic shifts in this tropical mountaintop vegetation. We found evidence to support the idea that environmental filtering is significantly shaping the distribution of biological communities and is restraining clades in the phylogeny. We argue that our study offers new insights into the biogeographic history and distributional shifts of the ancient rocky grasslands flora and to mountaintop vegetation systems in general. Department of Botany Federal University of São Carlos Department of Biodiversity São Paulo State University-UNESP, Avenue Department of Biodiversity São Paulo State University-UNESP, Avenue

Aims Phosphorus (P) availability and efficiency are especially important for plant growth and productivity. However, the sex-specific P acquisition and utilization strategies of dioecious plant species under different N forms are not clear. Methods This study investigated the responsive mechanisms of dioecious Populus cathayana females and males based on P uptake and allocation to soil P supply under N deficiency, nitrate (NO3−) and ammonium (NH4+) supply. Important Findings Females had a greater biomass, root length density (RLD), specific root length (SRL) and shoot P concentration than males under normal P availability with two N supplies. NH4+ supply led to higher total root length, RLD and SRL but lower root tip number than NO3− supply under normal P supply. Under P deficiency, males showed a smaller root system but greater photosynthetic P availability and higher leaf P remobilization, exhibiting a better capacity to adaptation to P deficiency than females. Under P deficiency, NO3− supply increased leaf photosynthesis and P use efficiency (PUE) but reduced RLD and SRL in females while males had higher leaf P redistribution and photosynthetic PUE than NH4+ supply. Females had a better potentiality to cope with P deficiency under NO3− supply than NH4+ supply; the contrary was true for males. These results suggest that females may devote to increase in P uptake and shoot P allocation under normal P availability, especially under NO3− supply, while males adopt more efficient resource use and P remobilization to maximum their tolerance to P deficiency.

Aims Invasive plants may alter soil fungal communities in a way that improves their growth. Nitrogen (N) content of soil affects the symbiosis between plants and arbuscular mycorrhizal fungi (AMF), further determining plant growth. Yet, it is unclear whether altered AMF communities change the dependence of invasive and native species on N-form, and whether N forms alter the invasive plant–AMF interaction (PSIM). Methods Two synthetic plant communities, including four Solidago canadensis individuals and four native plant species, were inoculated with AMF spores from S. canadensis-invaded soils and adjacent non-invaded soils, and were provided with nitrate, ammonia or glutamate. After their growth, the performance of the two plant communities in treatments of AMF origin and N forms, and the pathways of the N forms affecting S. canadensis growth and PSIM were evaluated. Important Findings Solidago canadensis had no obvious N-form dependence in any of the AMF inoculations. Native plant species showed weak N-form dependence, but invasive AMF could remove their N-form dependence. In the absence of N, AMF did not affect growth of S. canadensis and the native plants. In contrast, with N addition, invasive AMF significantly increased belowground and total biomass of the invasive plants but not those of the native plants. Positive PSIM of S. canadensis was also evidently greater than that of native plant species and was realized through directly or indirectly regulating phenotypic traits including plant height, leaf number and number of rhizomes. Our findings emphasize the importance of plant–AMF interactions and a unique N-acquisition strategy during plant invasions.

The relative importance of introgression for diversification has long been a highly disputed topic in speciation research and remains an open question despite the great attention it has received over the past decade. Gene flow leaves traces in the genome similar to those created by incomplete lineage sorting (ILS), and identification and quantification of gene flow in the presence of ILS is challenging and requires knowledge about the true phylogenetic relationship among the species. We use whole nuclear, plastid, and organellar genomes from 12 species in the rapidly radiated, ecologically diverse, actively hybridizing genus of peatmoss (Sphagnum) to reconstruct the species phylogeny and quantify introgression using a suite of phylogenomic methods. We found extensive phylogenetic discordance among nuclear and organellar phylogenies, as well as across the nuclear genome and the nodes in the species tree, best explained by extensive ILS following the rapid radiation of the genus rather than by postspeciation introgression. Our analyses support the idea of ancient introgression among the ancestral lineages followed by ILS, whereas recent gene flow among the species is highly restricted despite widespread interspecific hybridization known in the group. Our results contribute to phylogenomic understanding of how speciation proceeds in rapidly radiated, actively hybridizing species groups, and demonstrate that employing a combination of diverse phylogenomic methods can facilitate untangling complex phylogenetic patterns created by ILS and introgression.

Background and Aims Internal seed morphological traits such as embryo characteristics and nutritive tissue can vary considerably within a plant lineage. These traits play a prominent role in germination processes and the success of seedling establishment, and are therefore under high selective pressure, especially in environments hostile to seedlings, such as arid, saline or highly dynamic habitats. We investigated the relationships of seed internal morphology and germination characteristics of 84 species of Amaranthaceae s.l., a family with numerous lineages that have adapted to stressful growing conditions. Methods We used seed cross-sections to assess embryo type and the ratios of embryo to seed surface and radicle to cotyledon length. Furthermore, seed mass, mean time to germination, habitat preferences and further plant traits such as C3 or C4 photosynthesis and life form were compiled for each species. Data were analysed using phylogenetic comparative methods. Key results We found embryo type (λ = 1), log seed mass (λ = 0.86) and the ratio of embryo to seed size (λ = 0.78) to be evolutionarily stable, with an annular embryo as ancestral in the family. Linked to shifts to the three derived embryos types (spiral, horseshoe-shaped and curved) is an increase in the ratio of root to cotyledon length and a reduction of nutritive tissue. We observed stabilizing selection towards seeds with relatively large embryos with longer radicles and less nutritive tissue that are able to germinate faster, especially in lineages with C4 photosynthesis and/or salt tolerance. Conclusions We conclude that the evolutionary shift of nutrient storage from perisperm to embryo provides an ecological advantage in extreme environments, because it enables faster germination and seedling establishment. Furthermore, the evolutionary shift towards a higher ratio of root to cotyledon length especially in small-seeded Amaranthaceae growing in saline habitats can provide an ecological advantage for fast seedling establishment.

[EN] Aims: The survival and ecological distribution of plants in arid habitats are mainly conditioned by water availability and physiological adaptations to withstand drought. In the present study, we have compared the physiological responses to drought of two Retama raetam (retama) subspecies from Tunisia, one of them living under the desert climate (subsp. raetam) and the other one growing on the coast (subsp. bovei). Methods: To physiologically characterize the two R. raetam subspecies, and to elucidate their main mechanisms underlying their tolerance to drought stress, parameters related to seed germination, growth, photosynthesis (net photosynthetic rate, intracellular CO2 concentration, transpiration rate, stomatal conductance and water-use efficiency) and accumulation of osmolytes (proline, glycine betaine [GB] and soluble sugars) were determined in 4-month-old plants subjected to stress for up to 1 month. Important Findings: Drought significantly inhibited germination, growth and all the evaluated photosynthetic parameters. Plants of R. raetam subsp. bovei were severely affected by drought after 3 weeks of treatment when photosynthesis rates were up to 7-fold lower than in the controls. At the same time, proline and GB significantly accumulated compared with the irrigated controls, but much less than in R. raetam subsp. raetam; in the latter subspecies, proline and GB increased to levels 24- and 6-fold higher, respectively, than in the corresponding controls. In summary, the population living in the desert region exhibited stronger tolerance to drought stress than that adapted to the semiarid littoral climate, suggesting that tolerance in R. raetam is dependent on accumulation of osmolytes., Dhikra Zayoud's stay in Valencia was supported by a grant from the Tunisian Ministry of Higher Education and Scientific Research.

Background and Aims Aridity is increasing in many regions of the world, but microclimatic conditions may buffer plant communities from the direct effects of decreased precipitation, creating habitat islands. However, reduced precipitation can also impact these communities indirectly by decreasing the suitability of the surrounding habitat, thus limiting incoming propagules and increasing the chances of population decline and species loss. We test whether decreased precipitation results in loss of species and functional diversity within habitat islands, evaluating in particular whether declines in species diversity and abundance are less likely to result in loss of functional diversity if species/individual loss is stochastic (i.e. independent of species/individual traits) and communities/populations are functionally redundant. Methods Lomas communities are discrete plant communities embedded in the Atacama Desert, maintained by the microclimatic conditions created by fog. We recorded species and functional diversity in six Lomas communities along a 500 km long precipitation gradient in northern Chile. Functional traits were measured in 20 individuals per species, in those species that accounted for approx. 75 % of the abundance at each site. We calculated functional diversity and functional redundancy of the community, and intraspecific functional variation. Key Results Decreased precipitation was associated with lower species diversity and lower species abundances. However, no traits or functional strategies increased or decreased consistently with precipitation, suggesting stochastic species/individual loss. Species with stress-tolerant strategies were predominant in all sites. Although species diversity decreased with decreasing precipitation, functional diversity remained unchanged. Lower functional redundancy in the drier sites suggests that mainly functionally redundant species were lost. Likewise, intraspecific functional variation was similar among communities, despite the lower species abundance in drier sites. Conclusions Decreased precipitation can impact habitat island communities indirectly by decreasing the suitability of the surrounding habitat. Our results support the idea that a stochastic loss of species/individuals from functionally redundant communities and populations does not result in loss of functional diversity.

BACKGROUND AND AIMS: Most theory addressing the evolution of pollen limitation in flowering plants focuses on stochasticity in the relative abundance of plant and pollinator populations affecting trade-offs in resource allocation to ovule production or pollinator attraction vs. seed maturation. Mating system evolution is an underappreciated but potentially widespread additional mechanism for the evolutionary emergence of pollen limitation in animal-pollinated self-compatible plants. METHODS: We model individual plant flowering phenologies influencing both pollinator attraction and geitonogamous self-fertilization caused by pollinator movements among flowers within plants, incorporating demographic but not environmental stochasticity. Plant phenology and the resulting pollen limitation are analysed at evolutionarily stable equilibria (ESS). Pollen limitation is measured by two quantities: the proportion of unpollinated flowers and the reduction in maternal fitness caused by inbreeding depression in selfed seeds. KEY RESULTS: When pollinators visit multiple flowers per plant, pollen limitation is never minimized at an ESS and results from the evolution of flowering phenologies balancing the amount and genetic composition (outbred vs. inbred) of pollen receipt. CONCLUSIONS: Results are consistent with previous theory demonstrating that pollen limitation can be an evolved property, not just a constraint; they complement existing models by showing that plant avoidance of inbreeding depression constitutes a genetic mechanism contributing to evolution of pollen limitation, in addition to ecological mechanisms previously studied.

International audience; Background and Aims Besides bananas belonging to the AAA triploid Mutika subgroup, which predominates in the Great Lakes countries, other AAA triploids as well as edible AA diploids, locally of considerable cultural weight, are cultivated in East Africa and in the nearby Indian Ocean islands as far as Madagascar. All these varieties call for the genetic identification and characterization of their interrelations on account of their regional socio-economic significance and their potential for banana breeding strategies. Methods An extensive sampling of all traditional bananas in East Africa and near Indian Ocean islands was genotyped with simple sequence repeat (SSR) markers, with particular emphasis on the diploid forms and on the bananas of the Indian Ocean islands, which remain poorly characterized. Key Results All the edible AA varieties studied here are genetically homogeneous, constituting a unique subgroup, here called Mchare', despite high phenotypic variation and adaptions to highly diverse ecological zones. At triploid level, and besides the well-known AAA Mutika subgroup, at least two other genetically related AAA subgroups specific to this region are identified. Neither of these East African AAA genotypes can be derived directly from the local AA Mchare diploids. However, it is demonstrated that the East African diploids and triploids together belong to the same genetic complex. The geographical distribution of their wild acuminata relatives allowed identification of the original area of this complex in a restricted part of island South-East Asia. The inferred origin leads to consideration of the history of banana introduction in Africa. Linked to biological features, documentation on the embedding of bananas in founding legends and myths and convincing linguistic elements were informative regarding the period and the peoples who introduced these Asian plants into Africa. The results point to the role of Austronesian-speaking peoples who colonized the Indian Ocean islands, particularly Madagascar, and reached the East African coasts. Conclusions Understanding of the relations between the components of this complex and identifying their Asian wild relatives and related cultivars will be a valuable asset in breeding programmes and will boost the genetic improvement of East African bananas, but also of other globally important subgroups, in particular the AAA Cavendish.

Aims Screening tree species in tropical rainforest according to their shade tolerance is important to efficiently manage the native trees of economic significance in secondary forest enrichment regimes. The objective of this study was to determine the whole-plant light compensation point (WPLCP) and compare the phenotypic plasticity in relation to growth and carbon allocation of Cariniana legalis and Gallesia integrifolia seedlings under low light availability. Methods Seedlings were cultivated for 77 days under conditions of five photosynthetically active radiation (PAR) (0.02, 1.1, 2.3, 4.5 and 5.9 mol photons m−2 day−1) in three replicates. Growth and carbon allocation variables were determined. Important Findings Growth rates of C. legalis were higher and lower than those of G. integrifolia under 1.1 and 5.9 mol photons m−2 day−1, respectively. The WPLCP differed significantly between the two species. In accordance with the criteria of the shade tolerance classification for these two tropical tree species, our results showed that C. legalis had lower WPLCP and phenotypic plasticity in terms of higher growth rates and greater shade tolerance than G. integrifolia. From a practical point of view, we demonstrated that the differential linkage between growth and changing PAR between the two species can become a useful tool for comparing and selecting tree species in forest enrichment projects.

Made available in DSpace on 2021-06-25T10:29:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-04-01 In generalist pollination systems, it has been assumed that pollinators play a minor role in the diversification of floral traits, but recent studies have pointed to a different scenario. Although pollination in Piper is considered generalist, there are flower and inflorescence variations among subclades that may be associated with different pollinator functional groups. Based on this, we aimed to test whether pollinators influenced the evolution of floral traits in a clade of generalist plants, by studying 17 co-occurring Piper spp. Sixteen species were insect-pollinated (46 species: bees, beetles and flies). We found no evidence of anemophily. Eight species were dependent on pollen vectors for sexual reproduction, but no correlation between floral and pollinator traits was recorded. None of the floral traits presented phylogenetic signal, and the evolution of these traits was not correlated. Nine species were independent of pollen vectors for sexual reproduction. We did not find any evidence of pollinator-driven floral diversification of Piper spp.; we suggest a possible role of abiotic factors as agents of selection on floral diversification. As self-pollination seems to be a common feature in the genus, the flexibility of mating systems could be another important factor related to the maintenance of floral phenotypic variation. Institute of Biosciences UNESP-São Paulo State University, Rua Prof. Dr. Antonio Celso Wagner Zanin Department of Botany Federal University of São Carlos Institute of Biosciences UNESP-São Paulo State University, Rua Prof. Dr. Antonio Celso Wagner Zanin

Background and Aims Different seed dormancy classes control the timing of germination via different cues. The ecological dissimilarities between classes therefore suggest that they are likely to be subject to different selective pressures, and that species within each class will have diverse functional responses. We aimed to investigate this by assessing how variation in the distribution of dormancy classes is correlated with regional environmental factors, in particular rainfall seasonality and temperature. Additionally, we compare the relative proportions of species with physiological (PD) or physical (PY) dormancy to assess whether dormancy class influences their ability to persist under different rainfall seasonality regimes. Methods Dormancy class was assigned for 3990 species from 281 genera occurring across two climate regions, with either winter or aseasonal rainfall, across temperate fire-prone Australia. All regions have similar vegetation and fire regimes. Using a Bayesian framework, we compared the distribution of dormancy classes across temperature and rainfall climate gradients, for threatened and common species. Key Results A high dormant:non-dormant species ratio highlighted the critical role of dormancy across our study regions. Critically, species showing PD were more likely to be threatened in aseasonal rainfall climate regions. Conclusions Our results support the assumption that dormancy is favoured in environments with stochastic disturbance

Aims Soil inorganic nitrogen (N) has long been recognized to play an important role in plant invasions. Whilst comparing the N use strategies of multiple invasive versus native plant congeners along an entire N gradient is key to understanding plant invasion success, there are few related studies. Methods We conducted a potted experiment with six invasive and native congeneric pairs, which were subjected to 11 nitrate/ammonium (NO3−/NH4+) ratios (i.e. 100% NO3− at one end and 100% NH4+ at the other end), each with low- and high-N levels. Each species–N combination was replicated eight times, and thus there were 2112 pots in total. We measured the following traits: the total biomass, growth advantage, biomass allocation, leaf chlorophyll content and low-N tolerance. Important Findings Invasive and native congeners grew well at any NO3−/NH4+ ratios, and their responses of growth, allocation and tolerance were approximately parallel along the 11 NO3−/NH4+ ratios across two N levels. Plant invaders grew larger and had greater chlorophyll contents, higher root biomass allocation and stronger low-N tolerance than their congeneric natives. These findings suggest that invasive and native plant congeners may utilize similar inorganic N forms (i.e. NO3− and NH4+) across an entire N composition gradient and that higher N use efficiencies could favor alien plants to invade new plant communities where congeneric natives are dominants.

Aims In plant eco-physiology, less negative (enriched) carbon 13 (13C) in the leaves indicates conditions of reducing leaf gas exchange through stomata, e.g. under drought. In addition, 13C is expected to be less negative in non-photosynthetic tissues as compared with leaves. However, these relationships in δ 13C from leaves (photosynthetic organs) to branches, stems and roots (non-photosynthetic organs) are rarely tested across multiple closely related tree species, multiple compartments, or in trees growing under extreme heat and drought. Methods We measured leaf-to-root 13C in three closely related desert acacia species (Acacia tortilis, A. raddiana and A. pachyceras). We measured δ 13C in leaf tissues from mature trees in southern Israel. In parallel, a 7-year irrigation experiment with 0.5, 1.0 or 4.0 L day−1 was conducted in an experimental orchard. At the end of the experiment, growth parameters and δ 13C were measured in leaves, branches, stems and roots. Important Findings The δ 13C in leaf tissues sampled from mature trees was ca. −27‰, far more depleted than expected from a desert tree growing in one of the Earth’s driest and hottest environments. Across acacia species and compartments, δ 13C was not enriched at all irrigation levels (−28‰ to ca. −27‰), confirming our measurements in the mature trees. Among compartments, leaf δ 13C was unexpectedly similar to branch and root δ 13C, and surprisingly, even less negative than stem δ 13C. The highly depleted leaf δ 13C suggests that these trees have high stomatal gas exchange, despite growing in extremely dry habitats. The lack of δ 13C enrichment in non-photosynthetic tissues might be related to the seasonal coupling of growth of leaves and heterotrophic tissues.

Aims Leaf size and shape as objects of natural selection can play adaptive roles, and can change with the age of leaves. They can differ between sexes in dioecious species, and in most cases, females have larger leaves. Previous studies showed that sexes of Adriana tomentosa differed in their leaf lobing. In this study, we investigated whether there were other differences between sexes in leaf size, shape and ecophysiology, and if those differences were connected with adaptations and reproductive roles in the sexes of A. tomentosa. Methods Physical and chemical features of young and old leaves originating from female and male A. tomentosa plants growing in two disjunct populations in eastern Australia were measured. We determined leaf area, perimeter length, serration, circularity, aspect ratio (AR), roundness and the ecophysiological factors: specific leaf area, dry matter content, leaf moisture, relative water content, δ 13C, δ 15N isotope compositions, carbon and nitrogen contents and C:N ratio. Leaf lobing, the degree of lamina damage and the content of photosynthetic pigments were also determined. Important Findings In both populations studied, the sex of plants significantly influenced almost all parameters connected with leaf morphology such as area, perimeter length, circularity, AR and roundness. Contrary to expectations, males from both populations had a greater leaf area that was independent of leaf age. Male leaves were more lobed with a longer perimeter, but they were less elongated and less serrated. Only small differences between female and male leaves were observed for the ecophysiological factors. The degree of leaf damage differed between sexes but also with population. Differences between sexes in leaf area and shape were not compensated by measured ecophysiological factors. However, leaf area may be compensated by other ecophysiological mechanisms related to leaf morphology, because females had greater leaf serration in comparison to males despite the smaller leaf area.

AimsSoil biota can affect plant–plant interactions and non-native plant invasions via plant–soil feedback (PSF). Understanding the drivers underlying interspecific variations in PSF is important for predicting the role of soil biota in non-native plant invasions. Recent studies found that PSF could be predicted by plant traits. The success of plant invasions is also linked with plant traits, suggesting a potential linkage between PSF and plant invasion via plant traits, but has not yet been tested. Here, we compared PSF between six phylogenetically paired co-occurring native and invasive plants, and explored the potential linkage between PSF with plant root traits.MethodsWe conducted a two-phase PSF experiment. Field collected soils were conditioned by the six plant species for 3 months firstly, then seedlings of these plants were grown in living or sterilized soils that had been conditioned by conspecific vs. heterospecific (the congener/confamilial species) individuals. We estimated effects of biota in conspecific (conspecific PSF) or heterospecific (heterospecific PSF) soils relative to sterilized soils, and the relative effects of biota in conspecific vs. heterospecific soils (PSF-away) on plant biomass.Important FindingsIn general, soil biota suppressed plant growth, and there were no differences in conspecific PSF, heterospecific PSF and PSF-away between native and invasive plants. PSF increased with rising plant fine-to-total root mass ratio in the presence of soil biota, and its value was comparable between native and invasive plants. Our results indicate that similarity in plant fine-to-total root mass ratio that predicted PSF may have partially led to the comparable PSFs between these native and invasive plants. Studies exploring the linkages among plant traits, PSF and plant invasions with more plants, in particular phylogenetically distant plants, are needed to improve our understanding of the role of soil biota in plant invasions.

Aims Competition, temperature and nutrient are the most important determinants of tree growth in the cold climate on the eastern Tibetan Plateau. Although many studies have reported their individual effects on tree growth, little is known about how the interactions of competition with fertilization and temperature affect root growth. We aim to test whether climate warming and fertilization promote competition and to explore the functional strategies of Picea asperata in response to the interactions of these factors. Methods We conducted a paired experiment including competition and non-competition treatments under elevated temperature (ET) and fertilization. We measured root traits, including the root tip number over the root surface (RTRS), the root branching events over the root surface (RBRS), the specific root length (SRL), the specific root area (SRA), the total fine root length and area (RL and RA), the root tips (RTs) and root branching (RB) events. These root traits are considered to be indicators of plant resource uptake capacity and root growth. The root biomass and the nutrient concentrations in the roots were also determined. Important Findings The results indicated that ET, fertilization and competition individually enhanced the nitrogen (N) and potassium (K) concentrations in fine roots, but they did not affect fine root biomass or root traits, including RL, RT, RA and RB. However, both temperature and fertilization, as well as their interaction, interacting with competition increased RL, RA, RT, RB and nutrient uptake. In addition, the SRL, SRA, RTRS and RBRS decreased under fertilization, the interaction between temperature and competition decreased SRL and SRA, while the other parameters were not affected by temperature or competition. These results indicate that P. asperata maintains a conservative nutrient strategy in response to competition, climate warming, fertilization and their interactions. Our results improve our understanding of the physiological and ecological adaptability of trees to global change.

Aims Many wetlands are polluted with both nutrients and toxic metals and vegetated largely by clonal plants. We hypothesized that eutrophication and clonal integration can increase phytoremediation of toxic metal pollution by increasing plant growth, even under the stress imposed by toxicity. Methods To test this hypothesis, single ramets of the common, widespread, floating, stoloniferous plant Pistia stratiotes L., were grown for 42 days at two levels of nutrient availability with and without 0.6 mg L−1 cadmium. Ramets were either severed from their vegetative offspring to prevent clonal integration or left connected, and severed offspring were either removed to eliminate intraclonal competition or left in place. Important Findings Plants subjected to cadmium addition accumulated almost twice as much dry mass if given the higher nutrient level, due mainly to a doubling of the number of clonal offspring. Severance had little effect on the final mass of the parent plus offspring ramets. Removing offspring following severance had no effect on the final mass of the parental ramet in the presence of added cadmium, but it did increase the final mass of the parent in the absence of cadmium. These results support the hypothesis that eutrophication can increase remediation of toxic metal pollution by aquatic macrophytes but provided no evidence that clonal integration can affect remediation. Species such as P. stratiotes may help remediate co-pollution of wetlands with toxic metals and nutrients, and fragmentation of clones may not affect their remediation capacity.

Background and Aims There is a paucity of empirical research and a lack of predictive models concerning the interplay between spatial scale and disturbance as they affect the structure and assembly of plant communities. We proposed and tested a trait dispersion-based conceptual model hypothesizing that disturbance reinforces assembly processes differentially across spatial scales. Disturbance would reinforce functional divergence at the small scale (neighbourhood), would not affect functional dispersion at the intermediate scale (patch) and would reinforce functional convergence at the large scale (site). We also evaluated functional and species richness of native and exotic plants to infer underlying processes. Native and exotic species richness were expected to increase and decrease with disturbance, respectively, at the neighbourhood scale, and to show similar associations with disturbance at the patch (concave) and site (negative) scales. Methods In an arid shrubland, we estimated species richness and functional dispersion and richness within 1 m2 quadrats (neighbourhood) nested within 100 m2 plots (patch) along a small-scale natural disturbance gradient caused by an endemic fossorial rodent. Data for the site scale (2500 m2 plots) were taken from a previous study. We also tested the conceptual model through a quantitative literature review and a meta-analysis. Key Results As spatial scale increased, disturbance sequentially promoted functional divergence, random trait dispersion and functional convergence. Functional richness was unaffected by disturbance across spatial scales. Disturbance favoured natives over exotics at the neighbourhood scale, while both decreased under high disturbance at the patch and site scales. Conclusions The results supported the hypothesis that disturbance reinforces assembly processes differentially across scales and hampers plant invasion. The quantitative literature review and the meta-analysis supported most of the model predictions.

Transposable elements (TEs) constitute a large fraction of plant genomes and are mostly present in a transcriptionally silent state through repressive epigenetic modifications, such as DNA methylation. TE silencing is believed to influence the regulation of adjacent genes, possibly as DNA methylation spreads away from the TE. Whether this is a general principle or a context-dependent phenomenon is still under debate, pressing for studying the relationship between TEs, DNA methylation, and nearby gene expression in additional plant species. Here, we used the grass Brachypodium distachyon as a model and produced DNA methylation and transcriptome profiles for 11 natural accessions. In contrast to what is observed in Arabidopsis thaliana, we found that TEs have a limited impact on methylation spreading and that only few TE families are associated with a low expression of their adjacent genes. Interestingly, we found that a subset of TE insertion polymorphisms is associated with differential gene expression across accessions. Thus, although not having a global impact on gene expression, distinct TE insertions may contribute to specific gene expression patterns in B. distachyon., Genome Biology and Evolution, 12 (11), ISSN:1759-6653

Grapevine red blotch virus (GRBV) is the causal agent of grapevine red blotch disease, which affects wine grapes and leads to reduced crop yield and quality. While some virus spread can be attributed to the propagation of infected plant material, a greenhouse assay recently demonstrated that the threecornered alfalfa hopper (Membracidae: Spissistilus festinus Say) can transmit GRBV between grapevines. While S. festinus is not considered an economic pest of wine grapes, this species is present in California vineyards and their feeding can cause petiole girdling. Recent surveys have noted a correlation between S. festinus populations and GRBV-positive vines in vineyard areas adjacent to riparian habitat. Here, S. festinus populations were monitored over a 2-yr period at multiple vineyard sites adjacent to riparian habitats. At each site, insects were sampled from ground covers and the vine canopy at the vineyard edge and interior, and vines in both locations were evaluated for petiole girdling. Results indicate that there was no difference in abundance of S. festinus at the vineyard edge and interior. Populations in the vine canopy were highest in the late spring and early summer, and this was followed by the appearance of petiole girdling, indicating a key period of potential GRBV transmission. Furthermore, activity in the vine canopy appears to be amplified when the quality of ground covers is reduced as the season progresses. That said, overall populations of S. festinus were relatively low and additional work is needed to characterize the timing and efficiency of transmission under field conditions.

AimsGunnera tinctoria is an unusual N-fixing plant species that has become invasive worldwide, generally in environments with a low evaporative demand and/or high rainfall. Amongst the many mechanisms that may explain its success as an introduced species, a contrasting phenology could be important but this may depend on an ability to grow and utilize nutrients under sub-optimal conditions. We examined whether G. tinctoria has an advantage in terms of a contrasting phenology and N-fixing capability, in comparisons with Juncus effusus, the native species most impacted by G. tinctoria invasions.MethodsWe made phenological assessments on a weekly or bi-weekly basis on long-established populations on Achill Island, Ireland, during 2016–2017. Data on leaf and inflorescence number, total leaf area, light interception and above-ground biomass were collected alongside measurements of soil temperature, moisture and oxidation–reduction potential. The significance of N-fixing ability for supporting seasonal growth was assessed using δ 15N isotopic assessments, together with in situ acetylene reduction measurements.Important FindingsThe timing of the initiation of growth of G. tinctoria and J. effusus varied between 2016 and 2017, with the earlier emergence and expansion of leaves of G. tinctoria, and the largest above-ground biomass associated with higher water availability. The early growth of G. tinctoria was dependent on preformed structures, with maximum canopy development occurring in late May, prior to that of J. effusus. Whilst N-fixation was observed in March, this made a more significant contribution to growth during the later stages of canopy development. Based on δ 15N isotopic analyses, early growth was predominantly associated with N-remobilization from the rhizomes, whilst seedlings were largely reliant on N-fixation. This emphasizes the importance of nutrient mobilization for early growth and shows that the importance of an N-fixing capability may vary developmentally, as well as during different stages of the invasion process.

Aims As one of the most important agents driving floral evolution, pollinators shape the diversity of flowers in angiosperms. However, most previous studies have only quantified pollinators driving the evolution of a single floral trait, and experimental estimates of the potential role of pollinators in shaping the evolution of floral trait associations are relatively rare. Methods We experimentally identified and estimated the pollinator-mediated directional and correlational selection on single floral traits and trait combinations across 2 years in an orchid species, Spiranthes sinensis. Important Findings Pollinators mediated directional selection for an earlier flowering start date and larger corolla size. Pollinators mediated positive correlational selection on the combinations of floral display traits and negative correlational selection on the combinations of flowering phenology and floral display traits. In addition, the strength of selection differed over time. Our results highlight the potential role of pollinators in driving the evolution of floral trait combinations and suggest that it is necessary to consider floral character functional associations when seeking to understand and predict the evolutionary trajectory of flowers in angiosperms.

AimsPlants have limited resources for defenses and species that invest in biotic defenses might exhibit leaves that invest less in other types of defenses. We have investigated whether plants that have few mechanical defenses, but have extrafloral nectaries (EFNs) patrolled by ants, are less prone to herbivory, compared with plants without EFNs that have tougher leaves.MethodsData from the literature were extracted to examine the reported levels of herbivory in plants with or without EFNs. In a savanna vegetation in southern Brazil, field data were collected in leaves from six tropical species and herbivory and specific leaf area (SLA) levels were measured. We further evaluated differences in herbivory and SLA among species and between plants with or without EFNs. In order to test the relationship between herbivory and leaf toughness we regressed average herbivory and average SLA per plant.Important FindingsPlants exhibited variable levels of leaf damage, but plants without ant defenses experienced the highest levels of leaf area loss to herbivory. Levels of mechanical defenses were also variable among the plant species. Plants without EFNs were tougher, exhibiting lower values of SLA. Although plants without EFNs had more sclerophyllous leaves, this mechanical defense was not sufficient to impair and/or reduce herbivore feeding, suggesting that the biotic defenses performed by patrolling ants might be more effective than investment in mechanical defenses associated with leaf palatability.

Background and Aims The relative contributions of inter- and intraspecific variation to phytolith shape and size have only been investigated in a limited number of studies. However, a detailed understanding of phytolith variation patterns among populations or even within a single plant specimen is of key importance for the correct taxonomic identification of grass taxa in fossil samples and for the reconstruction of vegetation and environmental conditions in the past. In this study, we used geometric morphometric analysis for the quantification of different sources of phytolith shape and size variation. Methods We used landmark-based geometric morphometric methods for the analysis of phytolith shapes in two extant grass species (Brachypodium pinnatum and B. sylvaticum). For each species, 1200 phytoliths were analysed from 12 leaves originating from six plants growing in three populations. Phytolith shape and size data were subjected to multivariate Procrustes analysis of variance (ANOVA), multivariate regression, principal component analysis and linear discriminant analysis. Key Results Interspecific variation largely outweighed intraspecific variation with respect to phytolith shape. Individual phytolith shapes were classified with 83 % accuracy into their respective species. Conversely, variation in phytolith shapes within species but among populations, possibly related to environmental heterogeneity, was comparatively low. Conclusions Our results imply that phytolith shape relatively closely corresponds to the taxonomic identity of closely related grass species. Moreover, our methodological approach, applied here in phytolith analysis for the first time, enabled the quantification and separation of variation that is not related to species discrimination. Our findings strengthen the role of grass phytoliths in the reconstruction of past vegetation dynamics.

Background and Aims Displacement of native plant species by non-native invaders may result from differences in their carbon economy, yet little is known regarding how variation in leaf traits influences native–invader dynamics across climate gradients. In Hawaii, one of the most heavily invaded biodiversity hotspots in the world, strong spatial variation in climate results from the complex topography, which underlies variation in traits that probably drives shifts in species interactions. Methods Using one of the most comprehensive trait data sets for Hawaii to date (91 species and four islands), we determined the extent and sources of variation (climate, species and species origin) in leaf traits, and used mixed models to examine differences between natives and non-native invasives. Key Results We detected significant differences in trait means, such that invasives were more resource acquisitive than natives over most of the climate gradients. However, we also detected trait convergence and a rank reversal (natives more resource acquisitive than invasives) in a sub-set of conditions. There was significant intraspecific trait variation (ITV) in leaf traits of natives and invasives, although invasives expressed significantly greater ITV than natives in water loss and photosynthesis. Species accounted for more trait variation than did climate for invasives, while the reverse was true for natives. Incorporating this climate-driven trait variation significantly improved the fit of models that compared natives and invasives. Lastly, in invasives, ITV was most strongly explained by spatial heterogeneity in moisture, whereas solar energy explains more ITV in natives. Conclusions Our results indicate that trait expression and ITV vary significantly between natives and invasives, and that this is mediated by climate. These findings suggest that although natives and invasives are functionally similar at the regional scale, invader success at local scales is contingent on climate.

Agent-based modelling (ABM) has become an established methodology in many areas of biology, ranging from the cellular to the ecological population and community levels. In plant science, two different scales have predominated in their use of ABM. One is the scale of populations and communities, through the modelling of collections of agents representing individual plants, interacting with each other and with the environment. The other is the scale of the individual plant, through the modelling, by functional–structural plant models (FSPMs), of agents representing plant building blocks, or metamers, to describe the development of plant architecture and functions within individual plants. The purpose of this review is to show key results and parallels in ABM for growth, mortality, carbon allocation, competition and reproduction across the scales from the plant organ to populations and communities on a range of spatial scales to the whole landscape. Several areas of application of ABMs are reviewed, showing that some issues are addressed by both population-level ABMs and FSPMs. Continued increase in the relevance of ABM to environmental science and management will be helped by greater integration of ABMs across these two scales.

Rice (Oryza sativa) was domesticated around 10,000 years ago and has developed into a staple for half of humanity. The crop evolved and is currently grown in stably wet and intermittently dry agro-ecosystems, but patterns of adaptation to differences in water availability remain poorly understood. While previous field studies have evaluated plant developmental adaptations to water deficit, adaptive variation in functional and hydraulic components, particularly in relation to gene expression, has received less attention. Here, we take an evolutionary systems biology approach to characterize adaptive drought resistance traits across roots and shoots. We find that rice harbors heritable variation in molecular, physiological, and morphological traits that is linked to higher fitness under drought. We identify modules of co-expressed genes that are associated with adaptive drought avoidance and tolerance mechanisms. These expression modules showed evidence of polygenic adaptation in rice subgroups harboring accessions that evolved in drought-prone agro-ecosystems. Fitness-linked expression patterns allowed us to identify the drought-adaptive nature of optimizing photosynthesis and interactions with arbuscular mycorrhizal fungi. Taken together, our study provides an unprecedented, integrative view of rice adaptation to water-limited field conditions.

International audience

Phenotypic plasticity enables plants to buffer against environmental stresses and match their phenotypes to local conditions. However, consistent conclusive evidence for adaptive plasticity has only been obtained for a few traits. More studies on a wider variety of plant functional traits and environmental factors are still needed to further understand the adaptive significance of plasticity. We grew 21 genotypes of the stoloniferous clonal plant Duchesnea indica under different light and nutrient conditions, and used selection gradient analyses to test the adaptive value (benefits) of morphological and physiological plasticity responding to variation in light and nutrient availability. Plants grown in shade exhibited lower values for fitness measures (fruit number, ramet number and biomass), shortened thinner internode length and decreased adult leaf chlorophyll content, but higher petiole length, specific leaf area and old leaf chlorophyll content, than plants grown without shade. Plants grown in the low nutrient condition had shorter petiole length, thicker and smaller leaf area, lower chlorophyll content, but higher fruit number and root:shoot ratio than plants grown under the high nutrient condition. Selection gradient analyses revealed that plasticity of petiole length and old leaf chlorophyll content in response to light variation was adaptive, and plasticity of old and adult leaf chlorophyll content in response to nutrient variation was adaptive. Therefore, the adaptive value of plasticity in different traits depends on the specific ecological context. Our findings contribute to understanding the adaptive significance of phenotypic plasticity of clonal plants in response to environmental variation.

The leaf economic spectrum (LES) quantifies correlations between key leaf traits across vascular plants and distills much of the variation in these traits to a single axis. The LES, remarkable in its near universality, has been extensively researched across a variety of contexts. However, parasitic plants relationship to the LES framework remains relatively unexplored. Because the LES is, in part, driven by physiological tradeoffs in the acquisition of carbon (C), in theory heterotrophy in parasitic plants, which supplants some of the essential functions of leaves, could lead to departures from the LES. Using global leaf trait data from the TRY database, this work assessed the overall representation of parasitic plants in the TRY database, then compared the LES suite of leaf traits in parasitic plants to their non-parasitic counterparts. Despite their unique physiology, parasitic plants did not deviate dramatically from the LES, although there were examples of differences in position on the LES and relationships among traits. Perhaps more importantly, parasitic plants are not well represented in the TRY database, making any conclusions here premature.

Many mosses and lichens thrive in high-elevation subalpine forests and even become dominant species on the forest floor. Although they play an irreplaceable ecological role in the forest, less is known about their eco-physiological status, and how their photosynthesis-related functional traits differ from those of co-occurring vascular plants. We determined the carbon, nitrogen and phosphorus concentrations and stoichiometric ratios, tissue mass per area, chlorophyll concentrations and photosynthetic light–response curves of three lichens, three mosses and four vascular plants in a subalpine forest in the eastern Tibetan Plateau of China. Trait values were compared among and within each group. The lichens possessed a higher nitrogen concentration than that of mosses. In addition, the two poikilohydric groups exhibited lower concentrations of nitrogen, phosphorus and chlorophyll, light-saturated assimilation rates and photosynthetic nutrient use efficiencies, and higher light compensation points than those of vascular plant leaves. Furthermore, variations in photosynthesis-related traits for lichen species reflect their different adaptation strategies to their corresponding environments. In contrast, the differences were weak among the three forest-floor mosses and the three herb species. These results demonstrate that the high abundance of understory lichens and mosses in the high-elevation subalpine forest cannot be explained by the photosynthesis-related traits.

The submerged plant species Carolina fanwort (Cabomba caroliniana) has become a dominant invasive aquatic plant in the Lake Taihu Basin (LTB) in China. Introduced species may escape their original specialist enemies and encounter fewer enemies in their new environment. They were assumed to have suffered less herbivory than native species as they are relatively unpalatable (the enemy release hypothesis [ERH]). The objective of this study was to compare the responses of C. caroliniana with those of co-occurring native species to herbivory from native herbivores. We conducted a mesocosm experiment to record the responses of C. caroliniana and two commonly co-occurring native submerged plant counterparts, water thyme (Hydrilla verticillata) and Eurasian watermilfoil (Myriophyllum spicatum), to herbivory by two native generalist gastropod snails, Radix swinhoei and Sinotaia quadrata. Plant morphological traits (total biomass, shoot/root [S/R] biomass ratio and relative growth rate [RGR]) and physiological traits (leaf total nonstructural carbohydrate [TNC], lignin, and cellulose) were recorded. The snail S. quadrata rarely influenced the plant traits of the three submerged plants. With the increasing numbers of R. swinhoei treatments, most of the plant traits of H. verticillata and M. spicatum changed, while those of C. caroliniana showed a relatively stable fluctuation. This result indicates that C. caroliniana is more resistant to herbivory by the snail R. swinhoei, which is consistent with the ERH hypothesis. This finding indicates that herbivorous snail species contributes to the invasion of C. caroliniana, which potentially alters the species composition of submerged plants in the plant community.