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1.
Phys Rev Lett ; 126(3): 038101, 2021 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-33543959

RESUMO

Reinforced elastic sheets surround us in daily life, from concrete shell buildings to biological structures such as the arthropod exoskeleton or the venation network of dicotyledonous plant leaves. Natural structures are often highly optimized through evolution and natural selection, leading to the biologically and practically relevant problem of understanding and applying the principles of their design. Inspired by the hierarchically organized scaffolding networks found in plant leaves, here we model networks of bending beams that capture the discrete and nonuniform nature of natural materials. Using the principle of maximal rigidity under natural resource constraints, we show that optimal discrete beam networks reproduce the structural features of real leaf venation. Thus, in addition to its ability to efficiently transport water and nutrients, the venation network also optimizes leaf rigidity using the same hierarchical reticulated network topology. We study the phase space of optimal mechanical networks, providing concrete guidelines for the construction of elastic structures. We implement these natural design rules by fabricating efficient, biologically inspired metamaterials.


Assuntos
Modelos Biológicos , Folhas de Planta/química , Membrana Basal/anatomia & histologia , Membrana Basal/química , Fenômenos Biomecânicos , Elasticidade , Magnoliopsida , Folhas de Planta/anatomia & histologia
2.
Nat Commun ; 12(1): 503, 2021 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-33479227

RESUMO

The source of oxygen to Earth's atmosphere is organic carbon burial, whilst the main sink is oxidative weathering of fossil carbon. However, this sink is to insensitive to counteract oxygen rising above its current level of about 21%. Biogeochemical models suggest that wildfires provide an additional regulatory feedback mechanism. However, none have considered how the evolution of different plant groups through time have interacted with this feedback. The Cretaceous Period saw not only super-ambient levels of atmospheric oxygen but also the evolution of the angiosperms, that then rose to dominate Earth's ecosystems. Here we show, using the COPSE biogeochemical model, that angiosperm-driven alteration of fire feedbacks likely lowered atmospheric oxygen levels from ~30% to 25% by the end of the Cretaceous. This likely set the stage for the emergence of closed-canopy angiosperm tropical rainforests that we suggest would not have been possible without angiosperm enhancement of fire feedbacks.


Assuntos
Atmosfera/química , Retroalimentação Fisiológica , Fogo , Magnoliopsida/metabolismo , Oxigênio/metabolismo , Algoritmos , Carbono/metabolismo , Ecossistema , Fósseis , Magnoliopsida/crescimento & desenvolvimento , Modelos Teóricos , Fatores de Tempo
3.
Am J Bot ; 108(1): 8-21, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33403666

RESUMO

All organisms engage in parasitic relations, as either parasites or hosts. Some species may even play both roles simultaneously. Among flowering plants, the most widespread form of parasitism is characterized by the development of an intrusive organ called the haustorium, which absorbs water and nutrients from the host. Despite this functionally unifying feature of parasitic plants, haustoria are not homologous structures; they have evolved 12 times independently. These plants represent ca. 1% of all extant flowering species and show a wide diversity of life histories. A great variety of plants may also serve as hosts, including other parasitic plants. This phenomenon of parasitic exploitation of another parasite, broadly known as hyper- or epiparasitism, is well described among bacteria, fungi, and animals, but remains poorly understood among plants. Here, we review empirical evidence of plant hyperparasitism, including variations of self-parasitism, discuss the diversity and ecological importance of these interactions, and suggest possible evolutionary mechanisms. Hyperparasitism may provide benefits in terms of improved nutrition and enhanced host-parasite compatibility if partners are related. Different forms of self-parasitism may facilitate nutrient sharing among and within parasitic plant individuals, while also offering potential for the evolution of hyperparasitism. Cases of hyperparasitic interactions between parasitic plants may affect the ecology of individual species and modulate their ecosystem impacts. Parasitic plant phenology and disperser feeding behavior are considered to play a major role in the occurrence of hyperparasitism, especially among mistletoes. There is also potential for hyperparasites to act as biological control agents of invasive primary parasitic host species.


Assuntos
Magnoliopsida , Orobanchaceae , Parasitos , Animais , Ecossistema , Interações Hospedeiro-Parasita , Plantas
4.
Ann Bot ; 127(2): 231-239, 2021 01 07.
Artigo em Inglês | MEDLINE | ID: mdl-33410906

RESUMO

BACKGROUND AND AIMS: The great diversity of floral characteristics among animal-pollinated plants is commonly understood to be the result of coevolutionary interactions between plants and pollinators. Floral antagonists, such as nectar thieves, also have the potential to exert an influence upon the selection of floral characteristics, but adaptation against floral antagonists has attracted comparatively little attention. We found that the corollas of hornet-pollinated Codonopsis lanceolata (Campanulaceae) and the tepals of bee-pollinated Fritillaria koidzumiana (Liliaceae) are slippery to nectar-thieving ants living in the plant's habitat; because the flowers of both species have exposed nectaries, slippery perianths may function as a defence against nectar-thieving ants. METHODS: We conducted a behavioural experiment and observed perianth surface microstructure by scanning electron microscopy to investigate the mechanism of slipperiness. Field experiments were conducted to test whether slippery perianths prevent floral entry by ants, and whether ant presence inside flowers affects pollination. KEY RESULTS: Scanning electron microscopy observations indicated that the slippery surfaces were coated with epicuticular wax crystals. The perianths lost their slipperiness when wiped with hexane. Artificial bridging of the slippery surfaces using non-slippery materials allowed ants to enter flowers more frequently. Experimental introduction of live ants to the Codonopsis flowers evicted hornet pollinators and shortened the duration of pollinator visits. However, no statistical differences were found in the fruit or seed sets of flowers with and without ants. CONCLUSIONS: Slippery perianths, most probably based on epicuticular wax crystals, prevent floral entry by ants that negatively affect pollinator behaviour. Experimental evidence of floral defence based on slippery surfaces is rare, but such a mode of defence may be widespread amongst flowering plants.


Assuntos
Formigas , Magnoliopsida , Animais , Abelhas , Flores , Néctar de Plantas , Polinização
5.
Am J Bot ; 108(1): 22-36, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33482683

RESUMO

The phrase "Darwin's abominable mystery" is frequently used with reference to a range of outstanding questions about the evolution of the plant group today known as the angiosperms. Here, I seek to more fully understand what prompted Darwin to coin the phrase in 1879, and the meaning he attached to it, by surveying the systematics, paleobotanical records, and phylogenetic hypotheses of his time. In the light of this historical research, I argue that Darwin was referring to the origin only of a subset of what are today called angiosperms: a (now obsolete) group equivalent to the "dicotyledons" of the Hooker and Bentham system. To Darwin and his contemporaries, the dicotyledons' fossil record began abruptly and with great diversity in the Cretaceous, whereas the gymnosperms and monocotyledons were thought to have fossil records dating back to the Carboniferous or beyond. Based on their morphology, the dicotyledons were widely seen by botanists in Darwin's time (unlike today) as more similar to the gymnosperms than to the monocotyledons. Thus, morphology seemed to point to gymnosperm progenitors of dicotyledons, but this hypothesis made the monocotyledons, given their (at the time) apparently longer fossil record, difficult to place. Darwin had friendly disagreements about the mystery of the dicotyledons' abrupt appearance in the fossil record with others who thought that their evolution must have been more rapid than his own gradualism would allow. But the mystery may have been made "abominable" to him because it was seen by some contemporary paleobotanists, most notably William Carruthers, the Keeper of Botany at the British Museum, as evidence for divine intervention in the history of life. Subsequent developments in plant systematics and paleobotany after 1879 meant that Darwin's letter was widely understood to be referring to the abrupt appearance of all angiosperms when it was published in 1903, a meaning that has been attached to it ever since.


Assuntos
Botânica , Magnoliopsida , Evolução Biológica , Fósseis , História do Século XIX , Masculino , Filogenia
6.
Oecologia ; 195(1): 163-171, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33392791

RESUMO

The causes of the gradients in species richness remain contentious because of multiple competing hypotheses, significant knowledge gaps, and regional effects of environmental and historical factors on species pools. Coastal zones are subject to particular sets of environmental constraints, thus identifying the drivers of species richness therein should shed light on the regional gradients of species diversity. Here, we investigate the geographic patterns and drivers of plant diversity across coastal regions while allowing for pervasive sampling deficiencies. Based on 142708 records of flowering plant occurrences, we mapped species richness and estimated the level of knowledge across the coastal zone of Brazil. Based on inventory completeness, we used linear regression models to test the predictive power of environmental variables that represent different environmental hypotheses. Few cells (25%) were well-surveyed, reflecting little knowledge about the distribution and diversity of flowering plants on the highly-populated Brazilian coast. Still, we found support for the habitat heterogeneity hypothesis as the best explanation of the variation in species richness of flowering plants in this region. Soil properties and water constraints are also important factors. Although our work emphasises the paucity of information on plant diversity in tropical and human-dominated areas, we show that knowledge limitations should not curb our capability of addressing hypotheses about species diversity.


Assuntos
Biodiversidade , Magnoliopsida , Brasil , Ecossistema , Humanos , Plantas
7.
Am Nat ; 197(1): E30-E39, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33417516

RESUMO

AbstractSoil microorganisms influence a variety of processes in plant communities. Many theoretical and empirical studies have shown that dynamic feedbacks between plants and soil microbes can stabilize plant coexistence by generating negative frequency-dependent plant population dynamics. However, inferring the net effects of soil microbes on plant coexistence requires also quantifying the degree to which they provide one species an average fitness advantage, an effect that has received little empirical attention. We conducted a greenhouse study to quantify microbially mediated stabilization and fitness differences among 15 pairs of annual plants that co-occur in southern California grasslands. We found that although soil microbes frequently generate negative frequency-dependent dynamics that stabilize plant interactions, they simultaneously generate large average fitness differences between species. The net result is that if the plant species are otherwise competitively equivalent, the impact of plant-soil feedbacks is to often favor species exclusion over coexistence, a result that becomes evident only by quantifying the microbially mediated fitness difference. Our work highlights that comparing the stabilizing effects of plant-soil feedbacks to the fitness difference they generate is essential for understanding the influence of soil microbes on plant diversity.


Assuntos
Magnoliopsida/fisiologia , Microbiologia do Solo , Magnoliopsida/microbiologia , Dinâmica Populacional
8.
Gene ; 765: 145103, 2021 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-32889057

RESUMO

Malvaceae s.l. is the largest family of Malvales, comprising more than 4225 species. Within Malvaceae, the phylogenetic relationships among subfamilies remain controversial. To resolve these relationships and explore plastome evolution in Malvaceae, we assembled a complete plastome data set of 39 Malvales species, including newly reported sequences for 13 Malvaceae and two Dipterocarpaceae species. All species possessed the typical quadripartite structure of angiosperm plastomes, but significant independent expansions of the Inverted Repeat regions were detected in Abelmoschus esculentus and Durio zibethinus. Nine coding sequences were identified with positively selected sites in Malvaceae. Several highly variable noncoding and coding regions were identified in the plastomes of Malvaceae that may be valuable for phylogenetic reconstruction at lower taxonomic levels. Phylogenetic reconstructions based on 78 protein-coding genes strongly supported nearly all relationships among Malvaceae subfamilies. The diversification of the subfamilies of Malvaceae was dated to the late Cretaceous and early Eocene, during a time of global warmth.


Assuntos
Malvaceae/genética , Plastídeos/genética , Evolução Molecular , Genes de Plantas/genética , Variação Genética/genética , Magnoliopsida/genética , Fases de Leitura Aberta/genética , Filogenia
9.
Proc Biol Sci ; 287(1941): 20202593, 2020 12 23.
Artigo em Inglês | MEDLINE | ID: mdl-33352073

RESUMO

Heteranthery, the presence of two or more anther types in the same flower, is taxonomically widespread among bee-pollinated angiosperms, yet has puzzled botanists since Darwin. We test two competing hypotheses for its evolution: the long-standing 'division of labour' hypothesis, which posits that some anthers are specialized as food rewards for bees whereas others are specialized for surreptitious pollination, and our new hypothesis that heteranthery is a way to gradually release pollen that maximizes pollen delivery. We examine the evolution of heteranthery and associated traits across the genus Clarkia (Onagraceae) and study plant-pollinator interactions in two heterantherous Clarkia species. Across species, heteranthery is associated with bee pollination, delayed dehiscence and colour crypsis of one anther whorl, and movement of that anther whorl upon dehiscence. Our mechanistic studies in heterantherous species show that bees notice, forage on and export pollen from each anther whorl when it is dehiscing, and that heteranthery promotes pollen export. We find no support for division of labour, but multifarious evidence that heteranthery is a mechanism for gradual pollen presentation that probably evolved through indirect male-male competition for siring success.


Assuntos
Abelhas , Flores , Magnoliopsida , Animais , Aptidão Genética , Pólen , Polinização , Seleção Genética
10.
Am J Bot ; 107(12): 1677-1692, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33315246

RESUMO

PREMISE: We tested 25 classic and novel hypotheses regarding trait-origin, trait-trait, and trait-environment relationships to account for flora-wide variation in life history, habit, and especially reproductive traits using a plastid DNA phylogeny of most native (96.6%, or 1494/1547 species) and introduced (87.5%, or 690/789 species) angiosperms in Wisconsin, USA. METHODS: We assembled data on life history, habit, flowering, dispersal, mating system, and occurrence across open/closed/mixed habitats across species in the state phylogeny. We used phylogenetically structured analyses to assess the strength and statistical significance of associations predicted by our models. RESULTS: Introduced species are more likely to be annual herbs, occupy open habitats, have large, visually conspicuous, hermaphroditic flowers, and bear passively dispersed seeds. Among native species, hermaphroditism is associated with larger, more conspicuous flowers; monoecy is associated with small, inconspicuous flowers and passive seed dispersal; and dioecy is associated with small, inconspicuous flowers and fleshy fruits. Larger flowers with more conspicuous colors are more common in open habitats, and in understory species flowering under open (spring) canopies; fleshy fruits are more common in closed habitats. Wind pollination may help favor dioecy in open habitats. CONCLUSIONS: These findings support predictions regarding how breeding systems depend on flower size, flower color, and fruit type, and how those traits depend on habitat. This study is the first to combine flora-wide phylogenies with complete trait databases and phylogenetically structured analyses to provide powerful tests of evolutionary hypotheses about reproductive traits and their variation with geographic source, each other, and environmental conditions.


Assuntos
Magnoliopsida , Flores , Magnoliopsida/genética , Melhoramento Vegetal , Polinização , História Reprodutiva , Wisconsin
11.
PLoS One ; 15(10): e0239847, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33095792

RESUMO

Green lacewings (Neuroptera: Chrysopidae) are key biological control agents found in a broad range of crops. Given the importance of enhancing their presence and conservation, in this study, we aim to identify and to determine the relative importance of the pollen consumed by Chrysoperla lucasina (Lacroix, 1936) from 29 pollen types offered by 51 native plant species sown in an experimental farm in Villarrubia in the south of Spain. For the purposes of this study, C. lucasina specimens were captured in the late spring of 2016 and 2017. The pollen types and other components in the alimentary canal of C. lucasina were microscopically identified using the transparency method, which is a novel technique applied to green lacewings captured in the field. The results show that (i) C. lucasina feeds on over half of the pollen types offered by the sown plant species, with no differences in behaviour by sex or year; (ii) Capsella bursa-pastoris was the most frequently identified pollen type in the alimentary canal; (iii) the majority of pollen types identified correspond to sown native plant species and not to surrounding plant species; and that (iv) most of the adults studied also consumed honeydew. Our feeding study has important implications for the selection of plant mixtures for ground cover restoration and flower vegetation strips in Mediterranean agroecosystems, which complements our previous findings on how C. lucasina use native plant species as host and reproduction sites. The plant species Capsella bursa-pastoris and Biscutella auriculata, which are best suited to provide pollen, host and reproduction sites for C. lucasina in late spring, should consequently be included in the proposed plant mixtures for Mediterranean agroecosystems.


Assuntos
Dieta , Insetos/fisiologia , Pólen/classificação , Polinização , Animais , Feminino , Magnoliopsida , Masculino
12.
Nat Commun ; 11(1): 5320, 2020 10 21.
Artigo em Inglês | MEDLINE | ID: mdl-33087730

RESUMO

MicroRNAs (miRNAs) are endogenous small RNAs of ∼21 nt that regulate multiple biological pathways in multicellular organisms. They derive from longer transcripts that harbor an imperfect stem-loop structure. In plants, the ribonuclease type III DICER-LIKE1 assisted by accessory proteins cleaves the precursor to release the mature miRNA. Numerous studies highlight the role of the precursor secondary structure during plant miRNA biogenesis; however, little is known about the relevance of the precursor sequence. Here, we analyzed the sequence composition of plant miRNA primary transcripts and found specifically located sequence biases. We show that changes in the identity of specific nucleotides can increase or abolish miRNA biogenesis. Most conspicuously, our analysis revealed that the identity of the nucleotides at unpaired positions of the precursor plays a crucial role during miRNA biogenesis in Arabidopsis.


Assuntos
Arabidopsis/genética , Arabidopsis/metabolismo , MicroRNAs/biossíntese , MicroRNAs/genética , RNA de Plantas/biossíntese , RNA de Plantas/genética , Proteínas de Arabidopsis/metabolismo , Pareamento Incorreto de Bases , Proteínas de Ciclo Celular/metabolismo , Magnoliopsida/genética , Magnoliopsida/metabolismo , MicroRNAs/química , MicroRNAs/metabolismo , Simulação de Dinâmica Molecular , Conformação de Ácido Nucleico , Polimorfismo de Nucleotídeo Único , Processamento Pós-Transcricional do RNA , RNA de Plantas/química , Ribonuclease III/metabolismo
13.
Proc Biol Sci ; 287(1934): 20200962, 2020 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-32873209

RESUMO

Although polyploidy is widespread across the plant Tree of Life, its long-term evolutionary significance is still poorly understood. Here, we examine the effects of polyploidy in explaining the large-scale evolutionary patterns within angiosperms by focusing on a single family exhibiting extensive interspecific variation in chromosome numbers. We inferred ploidy from haploid chromosome numbers for 80% of species in the most comprehensive species-level chronogram for the Brassicaceae. After evaluating a total of 94 phylogenetic models of diversification, we found that ploidy influences diversification rates across the Brassicaceae. We also found that despite diversifying at a similar rate to diploids, polyploids have played a significant role in driving present-day differences in species richness among clades. Overall, in addition to highlighting the complexity in the evolutionary consequences of polyploidy, our results suggest that rare successful polyploids persist while significantly contributing to the long-term evolution of clades. Our findings further indicate that polyploidy has played a major role in driving the long-term evolution of the Brassicaceae and highlight the potential of polyploidy in shaping present-day diversity patterns across the plant Tree of Life.


Assuntos
Brassicaceae/genética , Diploide , Poliploidia , Evolução Biológica , Variação Genética , Genoma de Planta , Magnoliopsida , Filogenia , Ploidias
14.
BMC Ecol ; 20(1): 53, 2020 09 29.
Artigo em Inglês | MEDLINE | ID: mdl-32993593

RESUMO

BACKGROUND: Pollen limitation occurs widely and has an important effect on flowering plants. The East Himalaya-Hengduan Mountains region is a global biodiversity hotspot. However, to our knowledge, no study has synthetically assessed the degree of pollen limitation in this area. The present study aims to reveal the degree of pollen limitation for the flowering plants growing on East Himalaya-Hengduan Mountains and to test whether the reproductive features or the elevation is closely correlated with the degree of pollen limitation in this area. RESULTS: We complied data from 76 studies, which included 96 species and 108 independent data records. We found that the flowering plants in this area undergo severe pollen limitation [overall Hedges' d = 2.004, with a 95% confidence interval (1.3264, 2.6743)] that is much higher than that of the flowering plants growing in many other regions around the world. The degree of pollen limitation was tested to determine the correlation with the capacity for autonomous self-reproduction and with the pollination pattern (generalized vs. specialized pollination) of plants. In addition, we found a clear relationship between elevation and the degree of pollen limitation, which indicates that plants might undergo more severe pollen limitation in relatively high places. CONCLUSIONS: This paper is the first to address the severe pollen limitation of the flowering plants growing in East Himalaya-Hengduan Mountains region. Moreover, we reveal the positive correlation between elevation and the degree of pollen limitation.


Assuntos
Magnoliopsida , Biodiversidade , Flores , Plantas , Pólen , Polinização , Reprodução
15.
PLoS One ; 15(9): e0238914, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32946472

RESUMO

The Atlantic Forest is considered the fourth most important biodiversity hotspot. Although almost 96% of its original area has been devastated, a large part of its remaining conserved area is inhabited by traditional communities. This research focused on two Quilombola communities who reside within the Núcleo Picinguaba of the Serra do Mar State Park, State of São Paulo, Brazil. The objective was to use a combination of ethnoecological and ecological approaches to select priority species for which to develop participatory conservation and sustainable management plans in protected areas in Brazil. We collaborated with community members to collect ethnobotanical and ethnoecological data and then measured the abundance of native species in local forests through phytosociological sampling. We used this information to assess the degree of threat to useful species using the Conservation Priority Index, adding an additional layer of analysis based on habitat successional categories. We then overlayed those useful species identified as highest risk locally with those federally listed as threatened or endangered. Based on this, we identified three species as priority for the development of sustainable management plans: Virola bicuhyba, Cedrella fissilis and Plinia edulis.


Assuntos
Conservação dos Recursos Naturais/métodos , Espécies em Perigo de Extinção/estatística & dados numéricos , Magnoliopsida/crescimento & desenvolvimento , Oceano Atlântico , Brasil/etnologia , Ecossistema , Etnobotânica , Florestas , Humanos , Magnoliopsida/classificação
16.
Am J Bot ; 107(9): 1253-1259, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32882073

RESUMO

PREMISE: As repeatedly shown, the remarkable variation in the genome size of angiosperms can be shaped by extrinsic selective pressures, including nutrient availability. Carnivory has evolved independently in 10 angiosperm clades, but all carnivorous plants share a common affinity to nutrient-poor habitats. As such, carnivory and genome reduction could be responses to the same environmental pressure. Indeed, the smallest genomes among flowering plants are found in the carnivorous family Lentibulariaceae, where a unique mutation in cytochrome c oxidase (COX) is suspected to promote genome miniaturization. Despite these hypotheses, a phylogenetically informed test of genome size and nutrient availability across carnivorous clades has so far been missing. METHODS: Using linear mixed models, we compared genome sizes of 127 carnivorous plants from 7 diverse angiosperm clades with 1072 of their noncarnivorous relatives. We also tested whether genome size in Lentibulariaceae reflects the presence of the COX mutation. RESULTS: The genome sizes of carnivorous plants do not differ significantly from those of their noncarnivorous relatives. Based on available data, no significant association between the COX mutation and genome miniaturization could be confirmed, not even when considering polyploidy. CONCLUSIONS: Carnivory alone does not seem to significantly affect genome size decrease. Plausibly, it might actually counterbalance the effect of nutrient limitation on genome size evolution. The role of the COX mutation in genome miniaturization needs to be evaluated by analysis of a broader data set because current knowledge of its presence across Lentibulariaceae covers less than 10% of the species diversity in this family.


Assuntos
Carnivoridade , Magnoliopsida/genética , Tamanho do Genoma , Genoma de Planta , Humanos , Filogenia , Poliploidia
17.
Int J Syst Evol Microbiol ; 70(10): 5453-5459, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32910750

RESUMO

The members of the genus Frankia are, with a few exceptions, a group of nitrogen-fixing symbiotic actinobacteria that nodulate mostly woody dicotyledonous plants belonging to three orders, eight families and 23 genera of pioneer dicots. These bacteria have been characterized phylogenetically and grouped into four molecular clusters. One of the clusters, cluster 1 contains strains that induce nodules on Alnus spp. (Betulaceae), Myrica spp., Morella spp. and Comptonia spp. (Myricaceae) that have global distributions. Some of these strains produce not only hyphae and vesicles, as other cluster 1 strains do, but also numerous sporangia in their host symbiotic tissues, hence their phenotype being described as spore-positive (Sp+). While Sp+ strains have resisted repeated attempts at cultivation, their genomes have recently been characterized and found to be different from those of all described species, being markedly smaller than their phylogenetic neighbours. We thus hereby propose to create a 'Candidatus Frankia alpina' species for some strains present in nodules of Alnus alnobetula and A. incana that grow in alpine environments at high altitudes or in subarctic environments at high latitudes.


Assuntos
Alnus/microbiologia , Frankia/classificação , Fixação de Nitrogênio , Filogenia , Nódulos Radiculares de Plantas/microbiologia , Técnicas de Tipagem Bacteriana , Magnoliopsida/microbiologia , Simbiose
18.
PLoS One ; 15(9): e0239268, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32991580

RESUMO

Nitraria sibirica Pall. is a shrub species belonging to the family of Nitrariaceae. It plays pivotal role in arid ecosystems since it is tolerant to high salinity and drought. This species is widely distributed throughout Mongolia and it is mostly found in arid ecosystems of Mongolian Gobi Desert. In this study, we developed allometric equations for estimating above-ground biomass of N. sibirica using various structural descriptors and pinpointed the best models. Variables that precisely predicted above-ground biomass were a combination of basal diameter, crown area, and height. The allometric growth equation constructed is not merely helpful to achieve accurate estimations of the above-ground biomass in shrub vegetation in the Gobi Desert of Mongolia, but also can provide a reference for the above-ground biomass of Nitraria species growing in analogous habitats worldwide. Therefore, our research purposes an important advance for biomass estimation in Gobi ecosystems and complements previous studies of shrub biomass worldwide. This study provides reasonable estimates of biomass of N. sibirica, which will be valuable in evaluations of biological resources, especially for quantifying the main summer diet of Gobi bears, and also can be an alternative tool for assessing carbon cycling in Gobi Desert.


Assuntos
Clima Desértico , Ecossistema , Magnoliopsida/crescimento & desenvolvimento , Biomassa , Mongólia , Estações do Ano
19.
PLoS One ; 15(9): e0232313, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32960879

RESUMO

Pollination services and honeybee health in general are important in the African savannahs particularly to farmers who often rely on honeybee products as a supplementary source of income. Therefore, it is imperative to understand the floral cycle, abundance and spatial distribution of melliferous plants in the African savannah landscapes. Furthermore, placement of apiaries in the landscapes could benefit from information on spatiotemporal patterns of flowering plants, by optimising honeybees' foraging behaviours, which could improve apiary productivity. This study sought to assess the suitability of simulated multispectral data for mapping melliferous (flowering) plants in the African savannahs. Bi-temporal AISA Eagle hyperspectral images, resampled to four sensors (i.e. WorldView-2, RapidEye, Spot-6 and Sentinel-2) spatial and spectral resolutions, and a 10-cm ultra-high spatial resolution aerial imagery coinciding with onset and peak flowering periods were used in this study. Ground reference data was collected at the time of imagery capture. The advanced machine learning random forest (RF) classifier was used to map the flowering plants at a landscape scale and a classification accuracy validated using 30% independent test samples. The results showed that 93.33%, 69.43%, 67.52% and 82.18% accuracies could be achieved using WorldView-2, RapidEye, Spot-6 and Sentinel-2 data sets respectively, at the peak flowering period. Our study provides a basis for the development of operational and cost-effective approaches for mapping flowering plants in an African semiarid agroecological landscape. Specifically, such mapping approaches are valuable in providing timely and reliable advisory tools for guiding the implementation of beekeeping systems at a landscape scale.


Assuntos
Criação de Abelhas/métodos , Monitoramento Ambiental/métodos , Magnoliopsida/crescimento & desenvolvimento , Animais , Abelhas/fisiologia , Conjuntos de Dados como Assunto , Pradaria , Quênia , Aprendizado de Máquina , Fotografação , Polinização
20.
Am J Bot ; 107(8): 1148-1164, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32830865

RESUMO

PREMISE: Whole-genome duplications (WGDs) are prevalent throughout the evolutionary history of plants. For example, dozens of WGDs have been phylogenetically localized across the order Brassicales, specifically, within the family Brassicaceae. A WGD event has also been identified in the Cleomaceae, the sister family to Brassicaceae, yet its placement, as well as that of WGDs in other families in the order, remains unclear. METHODS: Phylo-transcriptomic data were generated and used to infer a nuclear phylogeny for 74 Brassicales taxa. Genome survey sequencing was also performed on 66 of those taxa to infer a chloroplast phylogeny. These phylogenies were used to assess and confirm relationships among the major families of the Brassicales and within Brassicaceae. Multiple WGD inference methods were then used to assess the placement of WGDs on the nuclear phylogeny. RESULTS: Well-supported chloroplast and nuclear phylogenies for the Brassicales and the putative placement of the Cleomaceae-specific WGD event Th-ɑ are presented. This work also provides evidence for previously hypothesized WGDs, including a well-supported event shared by at least two members of the Resedaceae family, and a possible event within the Capparaceae. CONCLUSIONS: Phylogenetics and the placement of WGDs within highly polyploid lineages continues to be a major challenge. This study adds to the conversation on WGD inference difficulties by demonstrating that sampling is especially important for WGD identification and phylogenetic placement. Given its economic importance and genomic resources, the Brassicales continues to be an ideal group for assessing WGD inference methods.


Assuntos
Duplicação Gênica , Magnoliopsida/genética , Evolução Molecular , Genoma , Genoma de Planta/genética , Humanos , Filogenia , Poliploidia
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