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1.
Science ; 378(6624): 1079-1085, 2022 12 09.
Artigo em Inglês | MEDLINE | ID: mdl-36480621

RESUMO

North America has experienced a massive increase in cropland use since 1800, accompanied more recently by the intensification of agricultural practices. Through genome analysis of present-day and historical samples spanning environments over the past two centuries, we studied the effect of these changes in farming on the extent and tempo of evolution across the native range of the common waterhemp (Amaranthus tuberculatus), a now pervasive agricultural weed. Modern agriculture has imposed strengths of selection rarely observed in the wild, with notable shifts in allele frequency trajectories since agricultural intensification in the 1960s. An evolutionary response to this extreme selection was facilitated by a concurrent human-mediated range shift. By reshaping genome-wide diversity across the landscape, agriculture has driven the success of this weed in the 21st century.


Assuntos
Adaptação Fisiológica , Amaranthus , Efeitos Antropogênicos , Fazendas , Plantas Daninhas , Humanos , América do Norte , Plantas Daninhas/genética , Plantas Daninhas/fisiologia , Amaranthus/genética , Amaranthus/fisiologia , Adaptação Fisiológica/genética , Seleção Genética , Variação Genética
2.
PLoS One ; 17(2): e0263798, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35139125

RESUMO

Redroot pigweed (Amaranthus retroflexus L.) and slender amaranth (Amaranthus viridis L.) are becoming problematic weeds in summer crops, including cotton in Australia. A series of laboratory and field experiments were performed to examine the germination ecology, and seed persistence of two populations of A. retroflexus and A. viridis collected from the Goondiwindi and Gatton regions of Australia. Both populations of A. retroflexus and A. viridis behaved similarly to different environmental conditions. Initial dormancy was observed in fresh seeds of both species; however, germination reached maximum after an after-ripening period of two months at room temperature. Light was not a mandatory prerequisite for germination of both species as they could germinate under complete darkness. Although both species showed very low germination at the alternating day/night temperature of 15/5 C, these species germinated more than 40% between ranges of 25/15 C to 35/25 C. Maximum germination of A. retroflexus (93%) and A. viridis (86%) was observed at 35/25 C and 30/20, respectively. Germination of A. retroflexus and A. viridis was completely inhibited at osmotic potentials of -1.0 and -0.6 MPa, respectively. No germination was observed in both species at the sodium chloride concentration of 200 mM. A. retroflexus seedling emergence (87%) was maximum from the seeds buried at 1 cm while the maximum germination of A. viridis (72%) was observed at the soil surface. No seedling emergence was observed from a burial depth of 8 cm for both species. In both species, seed persistence increased with increasing burial depth. At 24 months after seed placement, seed depletion ranged from 75% (10 cm depth) to 94% (soil surface) for A. retroflexus, and ranged from 79% to 94% for A. viridis, respectively. Information gained from this study will contribute to an integrated control programs for A. retroflexus and A. viridis.


Assuntos
Amaranthus/crescimento & desenvolvimento , Gossypium/crescimento & desenvolvimento , Plantas Daninhas/crescimento & desenvolvimento , Amaranthus/classificação , Amaranthus/fisiologia , Austrália , Produtos Agrícolas/crescimento & desenvolvimento , Ecologia , Germinação/fisiologia , Humanos , Plantas Daninhas/fisiologia , Estações do Ano , Plântula/crescimento & desenvolvimento , Sementes/crescimento & desenvolvimento , Controle de Plantas Daninhas
3.
BMC Plant Biol ; 21(1): 500, 2021 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-34717554

RESUMO

BACKGROUND: Strawberries are a common crop whose yield success depends on the availability of pollinators. Invasive alien plants, such as Impatiens glandulifera and I. parviflora, are also attractive for bees and hoverflies, respectively, and occur in close proximity to strawberry cultivation areas. The aim of the study was to test whether alien plants may decrease pollination of strawberry cultivation. However, even if the pollinators are abundant, efficiency of their pollination may decrease as a result of revisits of flowers that were already probed. It is addressed by pollinators by scent marking. Moreover, such revisits can be determined by nectar replenishment, which may occur rapidly in nectar-rich flowers. We studied revisits to I. glandulifera by bumblebees and defined the factors that influence the probability of revisits (air temperature; pollinator species; family caste and size; flower area; sun radiation; and time of day). RESULTS: We found that the two alien species decreased the number of pollinators visiting strawberries. Apoidea, Bombini and Syrphidae significantly decreased on Fragaria × ananassa when alien Impatiens were present. We also revealed the influence of increasing air temperature on bumblebee foraging, which was particularly significant for female workers. At very high temperatures (> 37°C), bumblebee males revisited probed flowers less often than female workers. CONCLUSIONS: Our results demonstrate that in experimental conditions attractive alien species decrease pollination of strawberries, which may negatively affect production of this crop. Although the results have not been verified in real-life strawberry fields yet, we recommend that alien plant species that share the same pollinators and occur in close proximity of strawberries are controlled. Moreover, we found that revisits of probed flowers may weaken feeding efficiency of bumblebees. If revisits are not induced by nectar replenishment, then global warming may pose a serious threat to the survival of colonies, which may have consequences also for the plants that attract them, e.g., for strawberries.


Assuntos
Abelhas/fisiologia , Produtos Agrícolas/crescimento & desenvolvimento , Flores/crescimento & desenvolvimento , Fragaria/crescimento & desenvolvimento , Impatiens/crescimento & desenvolvimento , Plantas Daninhas/fisiologia , Polinização/fisiologia , Animais
4.
PLoS One ; 16(8): e0256623, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34437599

RESUMO

Imports of seeds for sowing are a major pathway for the introduction of contaminant seeds, and many agricultural weeds globally naturalised originally have entered through this pathway. Effective management of this pathway is a significant means of reducing future plant introductions and helps minimise agricultural losses. Using a national border inspection database, we examined the frequency, origin and identity of contaminant seeds within seed for sowing shipments entering New Zealand between 2014-2018. Our analysis looked at 41,610 seed lots across 1,420 crop seed species from over 90 countries. Overall, contamination was rare, occurring in 1.9% of all seed lots. Among the different crop types, the arable category had the lowest percentage of seed lots contaminated (0.5%) and the forage category had the highest (12.6%). Crop seeds Capsicum, Phaseolus and Solanum had the lowest contamination rates (0.0%). Forage crops Medicago (27.3%) and Trifolium (19.8%) had the highest contamination rates. Out of 191 genera recorded as contaminants, Chenopodium was the most common. Regulated quarantine weeds were the rarest contaminant type, only occurring in 0.06% of seed lots. Sorghum halepense was the most common quarantine species and was only found in vegetable seed lots. Vegetable crop seed lots accounted for approximately half of all quarantine species detections, Raphanus sativus being the most contaminated vegetable crop. Larger seed lots were significantly more contaminated and more likely to contain a quarantine species than smaller seed lots. These findings support International Seed Testing Association rules on maximum seed lot weights. Low contamination rates suggest industry practices are effective in minimising contaminant seeds. Considering New Zealand inspects every imported seed lot, utilises a working sample size 5 times larger than International Seed Testing Association rules require, trades crop seed with approximately half of the world's countries and imports thousands of crop seed species, our study provides a unique overview of contaminant seeds that move throughout the seed for sowing system.


Assuntos
Comércio , Plantas Daninhas/fisiologia , Sementes/fisiologia , Produtos Agrícolas/fisiologia , Nova Zelândia , Especificidade da Espécie
5.
Nat Plants ; 7(6): 725-729, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-34099902

RESUMO

Recent carbon dioxide (CO2) concentrations promoted higher parthenin concentrations in an invasive Parthenium hysterophorus biotype. Mean concentrations of parthenin, an allelopathic and defensive sesquiterpene lactone, were 49% higher at recent (~400 ppm) than at mid-twentieth-century (~300 ppm) CO2 concentrations, but did not vary in a non-invasive biotype, suggesting that recent increases in atmospheric CO2 may have already altered the chemistry of this destructive weed, potentially contributing to its invasive success.


Assuntos
Asteraceae/metabolismo , Dióxido de Carbono , Plantas Daninhas/metabolismo , Sesquiterpenos/metabolismo , Alelopatia , Asteraceae/fisiologia , Ecótipo , Espécies Introduzidas , Brotos de Planta/metabolismo , Plantas Daninhas/fisiologia , Toxinas Biológicas/metabolismo
6.
Plant Cell Environ ; 44(12): 3479-3491, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-33993534

RESUMO

Species interactions and mechanisms affect plant coexistence and community assembly. Despite increasing knowledge of kin recognition and allelopathy in regulating inter-specific and intra-specific interactions among plants, little is known about whether kin recognition mediates allelopathic interference. We used allelopathic rice cultivars with the ability for kin recognition grown in kin versus non-kin mixtures to determine their impacts on paddy weeds in field trials and a series of controlled experiments. We experimentally tested potential mechanisms of the interaction via altered root behaviour, allelochemical production and resource partitioning in the dominant weed competitor, as well as soil microbial communities. We consistently found that the establishment and growth of paddy weeds were more inhibited by kin mixtures compared to non-kin mixtures. The effect was driven by kin recognition that induced changes in root placement, altered weed carbon and nitrogen partitioning, but was associated with similar soil microbial communities. Importantly, genetic relatedness enhanced the production of intrusive roots towards weeds and reduced the production of rice allelochemicals. These findings suggest that relatedness allows allelopathic plants to discriminate their neighbouring collaborators (kin) or competitors and adjust their growth, competitiveness and chemical defense accordingly.


Assuntos
Alelopatia , Oryza/fisiologia , Feromônios/metabolismo , Plantas Daninhas/fisiologia
8.
Bull Math Biol ; 83(2): 13, 2021 01 07.
Artigo em Inglês | MEDLINE | ID: mdl-33415490

RESUMO

We explore the dynamics of invasive weeds by partial differential equation (PDE) modelling and applying dynamical system and phase portrait techniques. We begin by applying the method of characteristics to a preexisting PDE model of the spreading of T. fluminensis, an invasive weed which has been responsible for native forest depletion. We explore the system both at particular points in space and over all of space, in one dimension, as a function of time. Our model suggests that an increase in the rate of spread of the weed through space will increase the efficacy of control measures taken at the weed's spatial boundary. We then propose new competition models based on the previous model and explore the existence of travelling wave solutions. These models represent both the cases with (i) a competing native plant species which spreads through the forest and (ii) a non-mobile, established native plant species. In the former case, the model suggests that an increased mass-action coefficient between the competing species is sufficient and necessary for the transition of the forest into a state of coexistence. In the latter case, the result is not as strong: a sufficiently large rate of competition between the species excludes the possibility of native plant extinction and hence suggests that forest depletion will not occur, but does not imply coexistence. We perform some numerical simulations to support our analytic results. In all cases, we give a discussion on the physical and biological interpretations of our results. We conclude with some suggestions for future work and with a discussion of the advantages and disadvantages of the methods.


Assuntos
Espécies Introduzidas , Modelos Biológicos , Plantas Daninhas , Plantas Daninhas/fisiologia , Dinâmica Populacional , Tradescantia/fisiologia
9.
Theor Appl Genet ; 134(3): 941-958, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33388884

RESUMO

KEY MESSAGE: Genome-wide association revealed that resistance to Striga hermonthica is influenced by multiple genomic regions with moderate effects. It is possible to increase genetic gains from selection for Striga resistance using genomic prediction. Striga hermonthica (Del.) Benth., commonly known as the purple witchweed or giant witchweed, is a serious problem for maize-dependent smallholder farmers in sub-Saharan Africa. Breeding for Striga resistance in maize is complicated due to limited genetic variation, complexity of resistance and challenges with phenotyping. This study was conducted to (i) evaluate a set of diverse tropical maize lines for their responses to Striga under artificial infestation in three environments in Kenya; (ii) detect quantitative trait loci associated with Striga resistance through genome-wide association study (GWAS); and (iii) evaluate the effectiveness of genomic prediction (GP) of Striga-related traits. An association mapping panel of 380 inbred lines was evaluated in three environments under artificial Striga infestation in replicated trials and genotyped with 278,810 single-nucleotide polymorphism (SNP) markers. Genotypic and genotype x environment variations were significant for measured traits associated with Striga resistance. Heritability estimates were moderate (0.42) to high (0.92) for measured traits. GWAS revealed 57 SNPs significantly associated with Striga resistance indicator traits and grain yield (GY) under artificial Striga infestation with low to moderate effect. A set of 32 candidate genes physically near the significant SNPs with roles in plant defense against biotic stresses were identified. GP with different cross-validations revealed that prediction of performance of lines in new environments is better than prediction of performance of new lines for all traits. Predictions across environments revealed high accuracy for all the traits, while inclusion of GWAS-detected SNPs led to slight increase in the accuracy. The item-based collaborative filtering approach that incorporates related traits evaluated in different environments to predict GY and Striga-related traits outperformed GP for Striga resistance indicator traits. The results demonstrated the polygenic nature of resistance to S. hermonthica, and that implementation of GP in Striga resistance breeding could potentially aid in increasing genetic gain for this important trait.


Assuntos
Resistência à Doença/genética , Melhoramento Vegetal , Doenças das Plantas/genética , Plantas Daninhas/fisiologia , Polimorfismo de Nucleotídeo Único , Locos de Características Quantitativas , Striga/fisiologia , Zea mays/genética , Alelos , Mapeamento Cromossômico/métodos , Cromossomos de Plantas/genética , Resistência à Doença/imunologia , Ligação Genética , Marcadores Genéticos , Estudo de Associação Genômica Ampla , Doenças das Plantas/parasitologia , Zea mays/imunologia , Zea mays/parasitologia
10.
Photosynth Res ; 149(1-2): 121-134, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32297101

RESUMO

Biological invasion is a hot topic in ecological research. Most studies on the physiological mechanisms of plants focus on leaves, but few studies focus on stems. To study the tolerance of invasive plant (Sphagneticola trilobata L.) to low temperature, relevant physiological indicators (including anthocyanin and chlorophyll) in different organs (leaves and stems) were analyzed, using a native species (Sphagneticola calendulacea L.) as the control. The results showed that, upon exposure to low temperature for 15 days, the stems of two Sphagneticola species were markedly reddened, their anthocyanin content increased, chlorophyll and chlorophyll fluorescence parameters decreased, and the accumulation of reactive oxygen species in the stem increased. The percentage increases of antioxidants and total antioxidant capacities in stems were significantly higher in S. trilobata than in S. calendulacea. This showed that S. trilobata had higher cold tolerance in stems while leaves were opposite. To further verify the higher cold tolerance of the stem of S. trilobata, a defoliation experiment was designed. We found that the defoliated stem of S. trilobata reduced anthocyanin accumulation and increased chlorophyll content, while alleviating membrane lipid damage and electrical conductivity, and the defoliated stem still showed an increase in stem diameter and biomass under low temperature. The discovery of the physiological and adaptive mechanisms of the stem of S. trilobata to low temperature will provide a theoretical basis for explaining how S. trilobata maintains its annual growth in South China. This is of great significance for predicting the future spread of cloned and propagated invasive plants.


Assuntos
Adaptação Fisiológica , Asteraceae/fisiologia , Temperatura Baixa/efeitos adversos , Fotossíntese/fisiologia , Folhas de Planta/fisiologia , Caules de Planta/fisiologia , Plantas Daninhas/fisiologia , China , Espécies Introduzidas
11.
Sci Rep ; 10(1): 19315, 2020 11 09.
Artigo em Inglês | MEDLINE | ID: mdl-33168869

RESUMO

Carabids are generalist predators that contribute to the agricultural ecosystem service of seedbank regulation via weed seed predation. To facilitate adoption of this ecosystem services by farmers, knowledge of weed seed predation and the resilience of seedbank regulation with co-varying availability of alternative prey is crucial. Using assessments of the seedbank and predation on seed cards in 57 cereal fields across Europe, we demonstrate a regulatory effect on the soil seedbank, at a continental scale, by groups formed of omnivore, seed-eating (granivore + omnivore) and all species of carabids just prior to the crop-harvest. Regulation was associated with a positive relationship between the activity-density of carabids and seed predation, as measured on seed cards. We found that per capita seed consumption on the cards co-varied negatively with the biomass of alternative prey, i.e. Aphididae, Collembola and total alternative prey biomass. Our results underline the importance of weed seedbank regulation by carabids, across geographically significant scales, and indicate that the effectiveness of this biocontrol may depend on the availability of alternative prey that disrupt the weed seed predation.


Assuntos
Agricultura/métodos , Besouros/fisiologia , Ecossistema , Plantas Daninhas/fisiologia , Sementes/fisiologia , Animais , Biomassa , Ecologia , Grão Comestível , Europa (Continente) , Hordeum , Modelos Lineares , Comportamento Predatório , Triticum
12.
Plant Physiol Biochem ; 157: 70-78, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33091798

RESUMO

Aegilops tauschii Coss, a notorious wheat field weed, poses a serious threat to wheat in China. Tillers are an important agronomic tool for yield. In this study, a total of 12 Ae. tauschii populations were collected from China to investigate the effect of plant density on tiller occurrence and its phytohormonal regulation. We assayed the growth parameters of Ae. tauschii and the levels of endogenous hormones at different plant densities. The results showed that plant density had a significant effect on the quantity and quality of Ae. tauschii seeds produced per plant. In particular, the tiller and spike numbers per plant were negatively affected by plant density (P < 0.0001). The contents of 13 endogenous hormones in the tiller nodes changed in response to plant density. Among them, indole-3-acetic acid (IAA) and gibberellin (GA) positively responded to plant density. However, the reverse result was found for cytokinin (CTK). Interestingly, phylogenetic tree analysis of auxin (AeYUCCA), CK (AeIPT) and GA (AeCPS) biosynthesis related genes found that phylogenies in the Gramineae for the three different genes were various, hinting at horizontal gene transfer. Moreover, the dynamics of the expression of AeYUCCA, AeIPT and AeCPS were roughly consistent with their phytohormone contents during tillering stage. When externally sprayed on plants of Ae. tauschii, 2,4-D isooctyl ester and GA3 markedly reduced its tillering while 6-BA had no significant effect.


Assuntos
Aegilops/fisiologia , Reguladores de Crescimento de Plantas/fisiologia , Plantas Daninhas/fisiologia , Sementes/fisiologia , China
13.
Proc Natl Acad Sci U S A ; 117(41): 25618-25627, 2020 10 13.
Artigo em Inglês | MEDLINE | ID: mdl-32989136

RESUMO

Global trade has considerably accelerated biological invasions. The annual tropical teosintes, the closest wild relatives of maize, were recently reported as new agricultural weeds in two European countries, Spain and France. Their prompt settlement under climatic conditions differing drastically from that of their native range indicates rapid genetic evolution. We performed a phenotypic comparison of French and Mexican teosintes under European conditions and showed that only the former could complete their life cycle during maize cropping season. To test the hypothesis that crop-to-wild introgression triggered such rapid adaptation, we used single nucleotide polymorphisms to characterize patterns of genetic variation in French, Spanish, and Mexican teosintes as well as in maize germplasm. We showed that both Spanish and French teosintes originated from Zea mays ssp. mexicana race "Chalco," a weedy teosinte from the Mexican highlands. However, introduced teosintes differed markedly from their Mexican source by elevated levels of genetic introgression from the high latitude Dent maize grown in Europe. We identified a clear signature of divergent selection in a region of chromosome 8 introgressed from maize and encompassing ZCN8, a major flowering time gene associated with adaptation to high latitudes. Moreover, herbicide assays and sequencing revealed that French teosintes have acquired herbicide resistance via the introgression of a mutant herbicide-target gene (ACC1) present in herbicide-resistant maize cultivars. Altogether, our results demonstrate that adaptive crop-to-wild introgression has triggered both rapid adaptation to a new climatic niche and acquisition of herbicide resistance, thereby fostering the establishment of an emerging noxious weed.


Assuntos
Adaptação Biológica/genética , Introgressão Genética/genética , Plantas Daninhas/genética , Zea mays/genética , Adaptação Biológica/fisiologia , Europa (Continente) , Evolução Molecular , Introgressão Genética/fisiologia , Resistência a Herbicidas/genética , Resistência a Herbicidas/fisiologia , Herbicidas/farmacologia , Plantas Daninhas/efeitos dos fármacos , Plantas Daninhas/fisiologia , Zea mays/efeitos dos fármacos , Zea mays/fisiologia
14.
PLoS One ; 15(8): e0237715, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32822374

RESUMO

Transcriptomic responses of plants to weed presence gives insight on the physiological and molecular mechanisms involved in the stress response. This study evaluated transcriptomic and morphological responses of two teosinte (Zea mays ssp parviglumis) (an ancestor of domesticated maize) lines (Ames 21812 and Ames 21789) to weed presence and absence during two growing seasons. Responses were compared after 6 weeks of growth in Aurora, South Dakota, USA. Plant heights between treatments were similar in Ames 21812, whereas branch number decreased when weeds were present. Ames 21789 was 45% shorter in weedy vs weed-free plots, but branch numbers were similar between treatments. Season-long biomass was reduced in response to weed stress in both lines. Common down-regulated subnetworks in weed-stressed plants were related to light, photosynthesis, and carbon cycles. Several unique response networks (e.g. aging, response to chitin) and gene sets were present in each line. Comparing transcriptomic responses of maize (determined in an adjacent study) and teosinte lines indicated three common gene ontologies up-regulated when weed-stressed: jasmonic acid response/signaling, UDP-glucosyl and glucuronyltransferases, and quercetin glucosyltransferase (3-O and 7-O). Overall, morphologic and transcriptomic differences suggest a greater varietal (rather than a conserved) response to weed stress, and implies multiple responses are possible. These findings offer insights into opportunities to define and manipulate gene expression of several different pathways of modern maize varieties to improve performance under weedy conditions.


Assuntos
Plantas Daninhas , Transcriptoma , Zea mays/crescimento & desenvolvimento , Regulação da Expressão Gênica de Plantas , Ontologia Genética , Luz , Fotossíntese , Plantas Daninhas/fisiologia , Estresse Fisiológico , Zea mays/genética , Zea mays/fisiologia
15.
J Environ Sci Health B ; 55(11): 1009-1019, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32816605

RESUMO

The present study addresses the herbicidal activity and biological effects of the metribuzin (MET) and tribenuron-methyl (TBM) herbicides used to control various weed species (Amaranthus retroflexus, Sinapis arvensis, and Leucanthemum maximum). The effects of the free herbicides and the herbicides embedded in granules of degradable polymer poly-3-hydroxybutyrate [P(3HB)] blended with birch wood flour were compared. Metribuzin, regardless of the form, caused 100% mortality of the three weeds by day 21. The herbicidal activity of tribenuron-methyl was lower than that of metribuzin, but the embedded TBM was superior to the free herbicide in the length and strength of its action on the weeds. Both metribuzin forms dramatically decreased the main parameters of fluorescence: maximum quantum yield of photosystem-II [Y(II)max], maximum quantum yield of non-photochemical quenching [Y(NPQ)max], and maximum rate of non-cyclic electron transport [ETRmax] and concentrations of chlorophyll a and b. The effect of the embedded TBM on the photosynthetic activity of the weeds was lower in the first two weeks of the growth of herbicide-treated plants but lasted longer than the effect of the free TBM and increased over time. Embedding of metribuzin in the matrix of degradable blend did not decrease its herbicidal activity.


Assuntos
Sulfonatos de Arila/farmacologia , Herbicidas/farmacologia , Plantas Daninhas/efeitos dos fármacos , Triazinas/farmacologia , Amaranthus/efeitos dos fármacos , Sulfonatos de Arila/química , Betula/química , Clorofila A/metabolismo , Preparações de Ação Retardada , Herbicidas/química , Hidroxibutiratos/química , Leucanthemum/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Plantas Daninhas/metabolismo , Plantas Daninhas/fisiologia , Poliésteres/química , Sinapis/efeitos dos fármacos , Triazinas/química , Madeira/química
16.
Proc Biol Sci ; 287(1930): 20201118, 2020 07 08.
Artigo em Inglês | MEDLINE | ID: mdl-32635863

RESUMO

Arable weeds are key organisms for biodiversity maintenance and ecosystem service provision in agroecosystems. Disentangling the drivers of weed diversity is critical to counteract the global decline of farmland biodiversity. Even if distinct scale-dependent processes were alternatively proposed, no general framework unifying the multi-scale drivers of weed dynamics has yet emerged. Here, we investigate the joint effects of field- and landscape-scale processes on weed assemblages in 444 arable fields. First, field margins sheltered greater weed diversity than field core, evidencing their role as biodiversity refugia. Second, community similarity between field core and margin decreased with the distance to margin, highlighting a major role of local dispersal. Third, weed diversity at field margins increased with organic field cover in the landscape, pointing out massive regional dispersal. Fourth, while both local and landscape dispersal explained up to 41% of field core weed diversity, crop type strongly modulated their strength, depicting an intense filtering effect by agricultural management. This study sheds new light on the complex multi-scale interactions shaping weed diversity, field margins playing a key role by strengthening regional dispersal and sustaining local dispersal. Land-sharing strategies improving habitat heterogeneity both locally and regionally should largely promote agroecosystem multifunctionality and sustainability.


Assuntos
Biodiversidade , Plantas Daninhas/fisiologia , Dispersão de Sementes , Agricultura , Animais , Ecossistema
17.
Nat Commun ; 11(1): 3086, 2020 06 18.
Artigo em Inglês | MEDLINE | ID: mdl-32555156

RESUMO

Intense selection by pesticides and antibiotics has resulted in a global epidemic of evolved resistance. In agriculture and medicine, using mixtures of compounds from different classes is widely accepted as optimal resistance management. However, this strategy may promote the evolution of more generalist resistance mechanisms. Here we test this hypothesis at a national scale in an economically important agricultural weed: blackgrass (Alopecurus myosuroides), for which herbicide resistance is a major economic issue. Our results reveal that greater use of herbicide mixtures is associated with lower levels of specialist resistance mechanisms, but higher levels of a generalist mechanism implicated in enhanced metabolism of herbicides with diverse modes of action. Our results indicate a potential evolutionary trade-off in resistance management, whereby attempts to reduce selection for specialist resistance traits may promote the evolution of generalist resistance. We contend that where specialist and generalist resistance mechanisms co-occur, similar trade-offs will be evident, calling into question the ubiquity of resistance management based on mixtures and combination therapies.


Assuntos
Evolução Molecular , Resistência a Herbicidas , Herbicidas , Poaceae/fisiologia , Controle de Plantas Daninhas , Produtos Agrícolas/fisiologia , Ecologia , Genes de Plantas , Geografia , Mutação , Fenótipo , Plantas Daninhas/fisiologia , Sementes , Regulação para Cima
18.
J Plant Physiol ; 250: 153184, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32464590

RESUMO

Although it is well known that parasitic weeds such as Orobanche (broomrape) significantly reduce the yield of economically important crops, their infection-induced oxidative changes need more exploration in their host plants. Moreover, applying an eco-friendly approach to minimize the infection is not yet available. This study was conducted to understand the effect of Orobanche ramosa infection on oxidative and redox status of tomato plants and the impact of hormonal (indole acetic acid (IAA); 0.09 mM and salicylic acid (SA); 1.0 mM) seed-priming upon mitigating the infection threats. Although Orobanche invades tomato roots, its inhibitory effects on shoot biomass were also indicted. Orobanche infection usually induces oxidative damage i.e., high lipid peroxidation, lipoxygenase activity and H2O2 levels, particularly for roots. Interestingly, hormonal seed-priming significantly enhanced tomato shoots and roots growth under both healthy and infected conditions. Also, IAA and SA treatment significantly reduced Orobanche infection-induced oxidative damage. The protective effect of seed-priming was explained by increasing the antioxidant defense markers including the antioxidant metabolites (i.e., total antioxidant capacity, carotenoids, phenolics, flavonoids, ASC, GSH, tocopherols) and enzymes (CAT, POX, GPX, SOD, GR, APX, MDHAR, DHAR), particularly in infected tomato seedlings. Additionally, cluster analysis indicated the differential impact of IAA- and SA-seed-priming, whereas lower oxidative damage and higher antioxidant enzymes' activities in tomato root were particularly reported for IAA treatment. The principal component analysis (PCA) also proclaimed an organ specificity depending on their response to Orobanche infection. Collectively, here and for the first time, we shed the light on the potential of seed-priming with either IAA or SA to mitigate the adverse effect of O. ramosa stress in tomato plants, especially at oxidative stress levels.


Assuntos
Ácidos Indolacéticos/farmacologia , Orobanche/fisiologia , Estresse Oxidativo/fisiologia , Reguladores de Crescimento de Plantas/farmacologia , Plantas Daninhas/fisiologia , Ácido Salicílico/farmacologia , /fisiologia , /efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Sementes/efeitos dos fármacos , Sementes/parasitologia , Sementes/fisiologia
19.
Curr Opin Insect Sci ; 38: 79-83, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32240966

RESUMO

Biocontrol of invasive alien weeds has produced great benefits, but concerns over undesirable impacts on non-target plants and/or indirect interactions between biocontrol agents and other biota impede the implementation of biocontrol in some countries. Although great strides have been made, continuing uncertainties predicting the realized host range of candidate agents is probably resulting in some being erroneously rejected due to overestimation of risk. Further refinement of host-range testing protocols is therefore desirable. Indirect interactions are inherently harder to predict, and the risk of both direct and indirect non-target impacts may change over time due to biocontrol agents evolving or expanding their range under climate change. Future research directions to better understand the risk of non-target impacts over time are discussed.


Assuntos
Controle Biológico de Vetores/métodos , Plantas Daninhas/fisiologia , Controle de Plantas Daninhas/métodos , Mudança Climática
20.
Curr Opin Insect Sci ; 38: 84-91, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32240967

RESUMO

Classical biological control (also called importation biological control) of weeds has a remarkable track record for efficiency and safety, but further improvement is still needed, particularly to account for potential evolutionary changes after release. Here, we discuss the increasing yet limited evidence of post-introduction evolution and describe approaches to predict evolutionary change. Recent advances include using experimental evolution studies over several generations that combine -omics tools with behavioral bioassays. This novel approach in weed biocontrol is well suited to explore the potential for rapid evolutionary change in real-time and thus can be used to estimate more accurately potential benefits and risks of agents before their importation. We outline this approach with a chrysomelid beetle used to control invasive common ragweed.


Assuntos
Ambrosia/fisiologia , Evolução Biológica , Besouros/fisiologia , Herbivoria , Controle Biológico de Vetores/métodos , Plantas Daninhas/fisiologia , Controle de Plantas Daninhas/métodos , Animais
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