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1.
PLoS One ; 16(9): e0257173, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34506557

RESUMO

Recent studies have revealed presence of fungus-originated genes in genomes of cool-season grasses, suggesting occurrence of multiple ancestral gene transfer events between the two distant lineages. The current article describes identification of glucanase-like and monooxygenase-like genes from creeping bent grass, as lateral gene transfer candidates. An in silico analysis suggested presence of the glucanase-like gene in Agrostis, Deyeuxia, and Polypogon genera, but not in other species belonging to the clade 1 of the Poeae tribe. Similarly, the monooxygenase-like gene was confined to Agrostis and Deyeuxia genera. A consistent result was obtained from PCR-based screening. The glucanase-like gene was revealed to be ubiquitously expressed in young seedlings of creeping bent grass. Although expression of the monooxygenase-like gene was suggested in plant tissues, the levels were considerably lower than those of the glucanase-like gene. A phylogenetic analysis revealed close relationships of the two genes between the corresponding genes in fungal endophyte species of the Epichloë genus, suggesting that the genes originated from the Epichloë lineage.


Assuntos
Agrostis/enzimologia , Agrostis/genética , Celulases/genética , Fungos/enzimologia , Genes de Plantas , Oxigenases de Função Mista/genética , Sequência de Aminoácidos , Celulases/química , Celulases/metabolismo , Regulação da Expressão Gênica de Plantas , Transferência Genética Horizontal , Oxigenases de Função Mista/química , Oxigenases de Função Mista/metabolismo , Filogenia
2.
Molecules ; 26(17)2021 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-34500767

RESUMO

Chitosan (CTS) is a deacetylated derivative of chitin that is involved in adaptive response to abiotic stresses. However, the regulatory role of CTS in heat tolerance is still not fully understood in plants, especially in grass species. The aim of this study was to investigate whether the CTS could reduce heat-induced senescence and damage to creeping bentgrass associated with alterations in antioxidant defense, chlorophyll (Chl) metabolism, and the heat shock pathway. Plants were pretreated exogenously with or without CTS (0.1 g L-1) before being exposed to normal (23/18 °C) or high-temperature (38/33 °C) conditions for 15 days. Heat stress induced detrimental effects, including declines in leaf relative water content and photochemical efficiency, but significantly increased reactive oxygen species (ROS) accumulation, membrane lipid peroxidation, and Chl loss in leaves. The exogenous application of CTS significantly alleviated heat-induced damage in creeping bentgrass leaves by ameliorating water balance, ROS scavenging, the maintenance of Chl metabolism, and photosynthesis. Compared to untreated plants under heat stress, CTS-treated creeping bentgrass exhibited a significantly higher transcription level of genes involved in Chl biosynthesis (AsPBGD and AsCHLH), as well as a lower expression level of Chl degradation-related gene (AsPPH) and senescence-associated genes (AsSAG12, AsSAG39, Asl20, and Ash36), thus reducing leaf senescence and enhancing photosynthetic performance under heat stress. In addition, the foliar application of CTS significantly improved antioxidant enzyme activities (SOD, CAT, POD, and APX), thereby effectively reducing heat-induced oxidative damage. Furthermore, heat tolerance regulated by the CTS in creeping bentgrass was also associated with the heat shock pathway, since AsHSFA-6a and AsHSP82 were significantly up-regulated by the CTS during heat stress. The potential mechanisms of CTS-regulated thermotolerance associated with other metabolic pathways still need to be further studied in grass species.


Assuntos
Agrostis/efeitos dos fármacos , Antioxidantes/farmacologia , Quitosana/farmacologia , Clorofila/metabolismo , Temperatura Alta , Folhas de Planta/efeitos dos fármacos , Agrostis/metabolismo , Resposta ao Choque Térmico/efeitos dos fármacos , Folhas de Planta/metabolismo
3.
Sci Total Environ ; 791: 148400, 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-34412406

RESUMO

Metal(loid) soil pollution resulting from mining activities is an important issue that has negative effects on the environment (soil acidification, lack of vegetation, groundwater pollution) and human health (cancer, chronic diseases). In the context of a phytostabilization process for the bioremediation of a mine soil highly contaminated by arsenic (As) and lead (Pb), a pot experiment was set up to study the effect of plant sowing and microbial inoculation on soil properties, metal(loid) (im)mobilization in soil and accumulation in plant, and plant growth. For this, mine soil was sown with endemic metallicolous Agrostis seeds and/or inoculated with endogenous microbial consortia previously selected for their As and Pb tolerance. Agrostis was able to develop on the contaminated mine soil and immobilized metal(loid)s through metal(loid) accumulation in the roots. Its growth was improved by microbial consortium inoculation. Moreover, microbial consortium inoculation increased soil organic content and electrical conductivity, and led to an increase in soil microbial activities (linked to C and P cycles); however, it also induced a metal(loid) mobilization. In conclusion, microbial consortium inoculation stimulated the growth of endemic Agrostis plants and thus ameliorated the phytostabilization of a former mine soil highly polluted by As and Pb. This study is thus a good example of the benefits of coupling several approaches such as phytostabilization and bioaugmentation for the bioremediation of former mine contaminated sites.


Assuntos
Agrostis , Poluentes do Solo , Biodegradação Ambiental , Humanos , Consórcios Microbianos , Solo , Poluentes do Solo/análise
4.
Mycologia ; 113(5): 956-967, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34236950

RESUMO

Leptosphaerulina leaf blight occurs on most turfgrasses. Hitherto, Leptosphaerulina species associated with this disease include L. americana, L. argentinensis, L. australis, and L. trifolii. However, following Koch's postulates, L. australis was confirmed as saprobes but not pathogens, and the other three species have not been tested. The pathogenicity of Leptosphaerulina spp. is still questionable. In this study, we isolated 19 Leptosphaerulina strains from diseased golf turfgrasses in China, and they were identified as L. gaeumannii, L. saccharicola, and a new species, L. macrospora, through multilocus (ITS, 28S, rpb2, and tub2) phylogenetic analyses and morphological observations. Pathogenicity test revealed that the three Leptosphaerulina species identified in this study cannot infect live/healthy turfgrass tissues of Poa pratensis and Agrostis stolonifera and only produced pseudothecia on the dead leaves of stressed seedlings. Considering the results of pathogenicity tests in this and previous studies, we speculate that most Leptosphaerulina species isolated from diseased turfgrass are not pathogens but saprobes. Applying proper management practices to prevent severe turfgrass stress is a key measure to reduce or eliminate the effects of Leptosphaerulina on golf turfgrass.


Assuntos
Agrostis , Ascomicetos , Golfe , Poa , Filogenia
5.
Appl Environ Microbiol ; 87(10)2021 04 27.
Artigo em Inglês | MEDLINE | ID: mdl-33741622

RESUMO

Dollar spot, caused by the fungal pathogen Clarireedia spp., is an economically important foliar disease of amenity turfgrass in temperate climates worldwide. This disease often occurs in a highly variable manner, even on a local scale with relatively uniform environmental conditions. The objective of this study was to investigate mechanisms behind this local variation, focusing on contributions of the soil and rhizosphere microbiome. Turfgrass, rhizosphere, and bulk soil samples were collected from within a 256-m2 area of healthy turfgrass, transported to a controlled environment chamber, and inoculated with Clarireedia jacksonii Bacterial communities were profiled by targeting the 16S rRNA gene, and 16 different soil chemical properties were assessed. Despite their initial uniform appearance, the samples differentiated into highly susceptible and moderately susceptible groups following inoculation in the controlled environment chamber. The highly susceptible samples harbored a unique rhizosphere microbiome with suggestively lower relative abundance of putative antibiotic-producing bacterial taxa and higher predicted abundance of genes associated with xenobiotic biodegradation pathways. In addition, stepwise regression revealed that bulk soil iron content was the only significant soil characteristic that positively regressed with decreased dollar spot susceptibility during the peak disease development stage. These findings suggest that localized variation in soil iron induces the plant to select for a particular rhizosphere microbiome that alters the disease outcome. More broadly, further research in this area may indicate how plot-scale variability in soil properties can drive variable plant disease development through alterations in the rhizosphere microbiome.IMPORTANCE Dollar spot is the most economically important disease of amenity turfgrass, and more fungicides are applied targeting dollar spot than any other turfgrass disease. Dollar spot symptoms are small (3 to 5 cm), circular patches that develop in a highly variable manner within plot scale even under seemingly uniform conditions. The mechanism behind this variable development is unknown. This study observed that differences in dollar spot development over a 256-m2 area were associated with differences in bulk soil iron concentration and correlated with a particular rhizosphere microbiome. These findings provide interesting avenues for future research to further characterize the mechanisms behind the highly variable development of dollar spot, which may inform innovative control strategies. Additionally, these results suggest that small changes in soil properties can alter plant activity and hence the plant-associated microbial community, which has important implications for a broad array of agricultural and horticultural plant pathosystems.


Assuntos
Agrostis/microbiologia , Ascomicetos , Ferro/análise , Doenças das Plantas/microbiologia , Rizosfera , Microbiologia do Solo , Solo/química , Bactérias/genética , Bactérias/isolamento & purificação , Microbiota , RNA Ribossômico 16S/genética
6.
Plant Cell Environ ; 44(6): 1769-1787, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33583055

RESUMO

Small heat shock proteins (sHSPs), a family of the ubiquitous stress proteins in plants acting as molecular chaperones to protect other proteins from stress-induced damage, have been implicated in plant growth and development as well as plant response to environmental stress, especially heat stress. In this study, a chloroplast-localized sHSP, AsHSP26.8, was overexpressed in creeping bentgrass (Agrostis stolonifera L.) to study its role in regulating plant growth and stress response. Transgenic (TG) creeping bentgrass plants displayed arrested root development, slow growth rate, twisted leaf blades and are more susceptible to heat and salt but less sensitive to drought stress compared to wild-type (WT) controls. RNA-seq analysis revealed that AsHSP26.8 modulated the expression of genes in auxin signalling and stress-related genes such as those encoding HSPs, heat shock factors and other transcription factors. Our results provide new evidence demonstrating that AsHSP26.8 negatively regulates plant growth and development and plays differential roles in plant response to a plethora of diverse abiotic stresses.


Assuntos
Agrostis/fisiologia , Proteínas de Cloroplastos/metabolismo , Proteínas de Choque Térmico Pequenas/metabolismo , Estresse Fisiológico/fisiologia , Agrostis/crescimento & desenvolvimento , Membrana Celular/genética , Membrana Celular/patologia , Clorofila/metabolismo , Proteínas de Cloroplastos/genética , Regulação da Expressão Gênica de Plantas , Proteínas de Choque Térmico Pequenas/genética , Folhas de Planta/genética , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Plantas Geneticamente Modificadas , Potássio/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Sódio/metabolismo , Água/metabolismo
7.
Plant Signal Behav ; 16(3): 1858247, 2021 03 04.
Artigo em Inglês | MEDLINE | ID: mdl-33470151

RESUMO

γ-Aminobutyric acid (GABA) acts as an important regulator involved in the mediation of cell signal transduction and stress tolerance in plants. However, the function of GABA in transcriptional regulation is not fully understood in plants under water stress. The creeping bentgrass (Agrostis stolonifera) was pretreated with or without GABA (0.5 mM) for 24 hours before being exposed to 5 days of water stress. Physiological analysis showed that GABA-treated plants maintained significantly higher endogenous GABA content, leaf relative water content, net photosynthetic rate, and lower osmotic potential than untreated plants under water stress. The GABA application also significantly alleviated stress-induced increases in superoxide anion (O2 .-) content, hydrogen peroxide (H2O2) content, and electrolyte leakage through enhancing total antioxidant capacity, superoxide dismutase (SOD) activity, and peroxidase (POD) activity in response to water stress. The transcriptomic analysis demonstrated that the GABA-induced changes in differentially expressed genes (DEGs) involved in carbohydrates, amino acids, and secondary metabolism helped to maintain better osmotic adjustment, energy supply, and metabolic homeostasis when creeping bentgrass suffers from water stress. The GABA triggered Ca2+-dependent protein kinase (CDPK) signaling and improved transcript levels of DREB1/2 and WRKY1/24/41 that could be associated with the upregulation of stress-related functional genes such as POD, DHNs, and HSP70 largely contributing to improved tolerance to water stress in relation to the antioxidant, prevention of cell dehydration, and protein protection in leaves.


Assuntos
Adaptação Fisiológica/genética , Agrostis/genética , Agrostis/fisiologia , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Estresse Fisiológico/genética , Ácido gama-Aminobutírico/metabolismo , Antioxidantes/metabolismo , Análise por Conglomerados , Desidratação , Perfilação da Expressão Gênica , Ontologia Genética , Anotação de Sequência Molecular , Transcriptoma/genética
8.
Sci Rep ; 11(1): 2347, 2021 01 27.
Artigo em Inglês | MEDLINE | ID: mdl-33504859

RESUMO

Plants can adjust defence strategies in response to signals from neighbouring plants attacked by aboveground herbivores. Whether similar responses exist to belowground herbivory remains less studied, particularly regarding the spatiotemporal dynamics of such belowground signalling. We grew the grass Agrostis stolonifera with or without root-feeding nematodes (Meloidogyne minor). Leachates were extracted at different distances from these plants and at different times after inoculation. The leachates were applied to receiver A. stolonifera plants, of which root, shoot, and total biomass, root/shoot ratio, shoot height, shoot branch number, maximum rooting depth and root number were measured 3 weeks after leachate application. Receiver plants allocated significantly more biomass to roots when treated with leachates from nematode-inoculated plants at early infection stages. However, receiver plants' root/shoot ratio was similar when receiving leachates collected at later stages from nematode-infected or control plants. Overall, early-collected leachates reduced growth of receiver plants significantly. Plants recently infected by root-feeding nematodes can thus induce increased root proliferation of neighbouring plants through root-derived compounds. Possible explanations for this response include a better tolerance of anticipated root damage by nematodes or the ability to grow roots away from the nematode-infected soil. Further investigations are still needed to identify the exact mechanisms.


Assuntos
Raízes de Plantas/parasitologia , Tylenchoidea/patogenicidade , Agrostis/parasitologia , Animais , Biomassa
9.
Plant Dis ; 105(2): 276-284, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32787654

RESUMO

Dollar spot is caused by the fungus Clarireedia spp. and is the most economically important disease of golf course turfgrass in temperate regions of the United States. Previous research has demonstrated that nitrogen (N) fertilization may reduce dollar spot severity, but the results have been inconsistent, and the impact of N as part of repeated foliar fertilization applications to golf course putting greens remains unclear. Two independent trials were replicated in Madison, Wisconsin and Glenview, Illinois in the 2015, 2016, and 2017 growing seasons. The objective of the first trial was to evaluate the effect of four different N rates applied as urea (4.9, 9.8, 19.4, and 29.3 kg N/ha applied every 2 weeks) on dollar spot severity, and the objective of the second trial was to evaluate the effect of three N sources (calcium nitrate, ammonium sulfate, and ammonium nitrate applied every 2 weeks) on dollar spot severity. Results from the N rate trial at both locations indicated that only the highest (29.3 kg N/ha) rate consistently reduced dollar spot severity relative to the nontreated control. Nitrogen source had minimal and inconsistent impacts on dollar spot severity based on location and year. Although these results show that meaningful reductions in dollar spot severity can be achieved by manipulating N fertilizer application rates, the rate of N needed for disease suppression may be impractical for most superintendents to apply and result in undesirable nontarget impacts.


Assuntos
Agrostis , Ascomicetos , Illinois , Nitrogênio/análise , Estados Unidos , Wisconsin
10.
Environ Geochem Health ; 43(4): 1457-1475, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31673918

RESUMO

Metal(loid) contamination of soil, resulting from the mining activities, is a major issue worldwide, due to its negative effects on the environment and health. Therefore, these contaminated soils need to be remediated. One realistic method is the assisted phytostabilization, which aims at establishing a vegetation cover on the soil that will reduce metal(loid) bioavailability and spreading through the prevention of wind erosion and water leaching. In addition, amendments are applied to improve soil conditions and ameliorate plant growth. In this goal, biochar and compost showed good results in terms of amelioration of soil fertility and reduction in lead bioavailability. However, they usually have a negative effect on arsenic. On the contrary, iron sulfate showed capacity to reduce arsenic mobility through interaction with its iron hydroxides. Finally, the choice of the appropriate plant species is crucial for the success of assisted phytostabilization. One good option is to use endemic species, adapted to the metal(loid) stress, with a fast growth and large shoot and root systems. The aims of this study were to (1) evaluate the effects of applying biochar, compost and iron sulfate, alone or combined, to a former mine soil on the soil properties and Agrostis capillaris growth, and (2) assess the difference between two Agrostis capillaris ecotypes, an endemic metallicolous ecotype and a non-metallicolous ecotype. Results of the mesocosm experiment showed that amendment application improved soil properties, i.e., reduced soil acidity, increased nutrient availability and lower metal(loid) stress, the best being the combination biochar-compost-iron sulfate. These ameliorations allowed a better plant growth. Finally, the metallicolous ecotype performed better in terms of growth than the non-metallicolous one and could thus be used in an assisted phytostabilization process on the former mine site.


Assuntos
Agrostis/efeitos dos fármacos , Carvão Vegetal , Chumbo/farmacocinética , Poluentes do Solo/farmacocinética , Solo/química , Agrostis/fisiologia , Arsênio/análise , Arsênio/farmacocinética , Biodegradação Ambiental , Compostagem , Ecótipo , Compostos Ferrosos/química , França , Chumbo/análise , Mineração , Poluentes do Solo/análise
11.
Plant Dis ; 105(3): 691-694, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32720885

RESUMO

Fungi in the genus Clarireedia are widespread and destructive pathogens of grasses worldwide, and are best known as the causal agents of dollar spot disease in turfgrass. Here, we report genome assemblies of seven Clarireedia isolates, including ex-types of the two most widespread species, Clarireedia jacksonii and C. monteithiana. These datasets provide a valuable resource for ongoing studies of the dollar spot pathogens that include population diversity, host-pathogen interactions, marker development, and disease control.


Assuntos
Agrostis , Ascomicetos , Ascomicetos/genética , Interações Hospedeiro-Patógeno , Poaceae
12.
Environ Geochem Health ; 43(4): 1491-1505, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32424789

RESUMO

Metal(loid) soil pollution is a major environmental and health issue, requiring these areas to be remediated, for example through phytoremediation processes. In order to allow proper plant establishment and growth, amendments must be applied to highly contaminated and poorly fertile soils. Amendments are diverse, but many studies have shown the beneficial effects of biochar, manure and ochre, although studies on their combined use are scarce. Moreover, no studies have evaluated the effect of these combined amendments on endemic plant growth. Endemic plants growing on contaminated soils showed higher tolerance toward pollutants compared to plants coming from unpolluted areas. Therefore, the aim of the present study was to evaluate both the effect of amendments (single or combined) on the physicochemical properties of a former mining technosol, and the growth and metal(loid) accumulation ability of endemic Agrostis capillaris plants. This study revealed an improvement in the soil physicochemical properties following the application of amendments, with combined amendments showing better results than the application of just one. On top of this, Agrostis plants performed better on the amended technosols, especially the ones receiving manure, due to its high nutrient content. Finally, based on soil properties, plant growth and the metal(loid) accumulation profile, the use of biochar combined with manure seems to be the most appropriate treatment. Indeed, this treatment showed an improvement in both soil fertility and plant growth. Moreover, Agrostis plants grown in these conditions were among those showing higher root metal(loid) concentration associated with a lower translocation toward aerial parts.


Assuntos
Agrostis/metabolismo , Arsênio/metabolismo , Biodegradação Ambiental , Carvão Vegetal , Ecótipo , Chumbo/metabolismo , Esterco , Mineração , Poluentes do Solo/metabolismo , Desenvolvimento Vegetal , Solo/química
13.
Environ Sci Pollut Res Int ; 28(11): 14115-14120, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33205278

RESUMO

Lawns and flower are major aesthetical and environmental elements of the urban ecosystem. However, harsh urban conditions such as pollution by heavy metals are unfavorable for plants. For example, copper is toxic for ornamental plants, limiting the spread of lawn grass and flowering plants. Therefore, here we hypothesized that plants could be adapted to urban conditions by breeding. We first showed the possibility of using environmental biotechnology in urban greening to obtain, tolerating copper flowering plants and lawn grasses. We tested the adaptation of creeping bentgrass (Agrostis stolonifera L.) and painted daisy (Chrysanthemum carinatum Schousb.) to сopper. We measured Cu resistance in the next generations of those plant species. Results show that some next generations of plant regenerants have increased resistance up to 100 mg/kg Cu for Agrostis stolonifera, and up to 30 mg/kg for Chrysanthemum carinatum. Our findings thus imply that city plants may be adapted and improved by сell selection. Our approach thus represents a novel biotechnology consisting of adapting plants to pollution by сell selection.


Assuntos
Agrostis , Poaceae , Cobre , Ecossistema , Melhoramento Vegetal
14.
BMC Plant Biol ; 20(1): 506, 2020 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-33148164

RESUMO

BACKGROUND: Chitosan (CTS), a natural polysaccharide, exhibits multiple functions of stress adaptation regulation in plants. However, effects and mechanism of CTS on alleviating salt stress damage are still not fully understood. Objectives of this study were to investigate the function of CTS on improving salt tolerance associated with metabolic balance, polyamine (PAs) accumulation, and Na+ transport in creeping bentgrass (Agrostis stolonifera). RESULTS: CTS pretreatment significantly alleviated declines in relative water content, photosynthesis, photochemical efficiency, and water use efficiency in leaves under salt stress. Exogenous CTS increased endogenous PAs accumulation, antioxidant enzyme (SOD, POD, and CAT) activities, and sucrose accumulation and metabolism through the activation of sucrose synthase and pyruvate kinase activities, and inhibition of invertase activity. The CTS also improved total amino acids, glutamic acid, and γ-aminobutyric acid (GABA) accumulation. In addition, CTS-pretreated plants exhibited significantly higher Na+ content in roots and lower Na+ accumulation in leaves then untreated plants in response to salt stress. However, CTS had no significant effects on K+/Na+ ratio. Importantly, CTS enhanced salt overly sensitive (SOS) pathways and also up-regulated the expression of AsHKT1 and genes (AsNHX4, AsNHX5, and AsNHX6) encoding Na+/H+ exchangers under salt stress. CONCLUSIONS: The application of CTS increased antioxidant enzyme activities, thereby reducing oxidative damage to roots and leaves. CTS-induced increases in sucrose and GABA accumulation and metabolism played important roles in osmotic adjustment and energy metabolism during salt stress. The CTS also enhanced SOS pathway associated with Na+ excretion from cytosol into rhizosphere, increased AsHKT1 expression inhibiting Na+ transport to the photosynthetic tissues, and also up-regulated the expression of AsNHX4, AsNHX5, and AsNHX6 promoting the capacity of Na+ compartmentalization in roots and leaves under salt stress. In addition, CTS-induced PAs accumulation could be an important regulatory mechanism contributing to enhanced salt tolerance. These findings reveal new functions of CTS on regulating Na+ transport, enhancing sugars and amino acids metabolism for osmotic adjustment and energy supply, and increasing PAs accumulation when creeping bentgrass responds to salt stress.


Assuntos
Agrostis/fisiologia , Quitosana/metabolismo , Poliaminas/metabolismo , Plantas Tolerantes a Sal/fisiologia , Sódio/metabolismo , Agrostis/metabolismo , Metabolismo Energético , Fotossíntese , Folhas de Planta/metabolismo , Folhas de Planta/fisiologia , Raízes de Plantas/metabolismo , Raízes de Plantas/fisiologia , Tolerância ao Sal , Plantas Tolerantes a Sal/metabolismo , Água/metabolismo
15.
J Plant Physiol ; 254: 153284, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33010664

RESUMO

The response of plant species to external factors depends partly on the interaction with the environment and with the other species that coexist in the same ecosystem. Several studies have investigated the main traits that determine the competitive capacity of plant species, and although the relevance of the traits is not clear, traits both from belowground and aboveground have been observed. In this paper, we grew Trifolium pratense and Agrostis capillaris in intra- and interspecific competition, analyzing the photosynthetic metabolism and nitrogen uptake, among other variables. The results indicated that T. pratense possesses better competition ability due to the higher competitive performance for soil resources compared to A. capillaris, explained by a higher root biomass and a higher nitrogen uptake rate in the former than in the latter. These traits permitted T. pratense to show higher photosynthetic rate than A. capillaris when both species were grown in mixture. Furthermore, the interspecific competition provoked A. capillaris to activate its antioxidant metabolism, through SOD activity, to detoxify the reactive oxygen species generated due to its lower capacity for using the photochemical energy absorbed. In this experiment, we conclude that the competitiveness seems to be more related with soil resources competition than with light competition, and that the photosynthetic rate decline in A. capillaris is more a secondary effect as a consequence of nitrogen limitation.


Assuntos
Agrostis/fisiologia , Pradaria , Trifolium/fisiologia , Agrostis/crescimento & desenvolvimento , Agrostis/metabolismo , Clorofila/metabolismo , Peroxidação de Lipídeos , Nitrogênio/metabolismo , Fotossíntese/fisiologia , Transpiração Vegetal/fisiologia , Solo , Superóxido Dismutase/metabolismo , Trifolium/crescimento & desenvolvimento , Trifolium/metabolismo
16.
Plant Physiol Biochem ; 157: 185-194, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33120110

RESUMO

The frequency and severity of global abiotic stresses such as heat, drought, and salt stress are increasing due to climate changes. Objectives of this study were to investigate effects of γ-aminobutyric acid (GABA) priming on inducing plants' acclimation to abiotic stress associated with alterations of endogenous polyamines (PAs), amino acids, and sugars in creeping bentgrass (Agrostis stolonifera). The pretreatment with GABA fertigation significantly alleviated heat-, drought-, and salt-induced declines in leaf relative water content, chlorophyll content, cell membrane stability, photochemical efficiency (Fv/Fm), and performance index on absorption basis (PIABS), and also further decreased stress-caused decline in osmotic potential in leaves. The GABA priming uniformly increased total PAs, spermidine, amino acids involved in GABA shunt (GABA, glutamic acid, and alanine), and other amino acids (phenylalanine, aspartic acid, and glycine) accumulation under heat, drought, and salt stress. The GABA priming also significantly improved methionine content under heat and drought stress, maltose, galactose, and talose content under heat and salt stress, or cysteine, serine, and threonine content under drought and salt stress. Interestingly, the GABA priming uniquely led to significant accumulation of spermine, fructose, and glucose under heat stress, putrescine, proline, and mannose under drought stress, or arginine, trehalose and xylose under salt stress, respectively. These particular PAs, sugars, and amino acids differentially or commonly regulated by GABA could play critical roles in osmotic adjustment, osmoprotection, antioxidant, energy source, and signal molecular for creeping bentgrass to acclimate diverse abiotic stresses.


Assuntos
Agrostis/fisiologia , Poliaminas/metabolismo , Estresse Fisiológico , Ácido gama-Aminobutírico/metabolismo , Adaptação Fisiológica , Secas , Temperatura Alta , Salinidade
17.
Plant Dis ; 104(12): 3118-3123, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33058719

RESUMO

Dollar spot is one of the most economically important diseases of turfgrasses. Recent taxonomic revisions have placed the dollar spot fungal pathogens in the new genus Clarireedia, with five species described. The main goal of this study was to develop a quantitative real-time PCR (qPCR) molecular detection assay based on the internal transcribed spacer (ITS) of the ribosomal RNA genes to quantify the abundance of Clarireedia spp. from environmental (field) samples. The qPCR assay was able to detect isolates of the four tested Clarireedia spp. but did not cross react with nontarget fungi, including closely related taxa, other turfgrass pathogens, or other fungal species commonly isolated from turfgrass. The assay is capable of detecting as little as 38.0 fg (3.8 × 10-14 g) of Clarireedia genomic DNA in 3 h. The qPCR assay detected Clarireedia spp. in both symptomatic and asymptomatic creeping bentgrass (Agrostis stolonifera) foliar tissue. Clarireedia spp. were rarely detected in the thatch or soil, indicating that these pathogens are not widely distributed in these areas of the environment. The fact that the pathogen was detected in asymptomatic tissue suggests that creeping bentgrass may be able to tolerate a certain quantity of the pathogens in leaves before disease symptoms appear; however, further research is needed to validate this hypothesis.


Assuntos
Agrostis , Ascomicetos , Agrostis/genética , Ascomicetos/genética , Doenças das Plantas , Folhas de Planta , Reação em Cadeia da Polimerase em Tempo Real
18.
Int J Mol Sci ; 21(20)2020 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-33050389

RESUMO

γ-Aminobutyric acid (GABA) plays an important role in regulating stress tolerance in plants. Purposes of this study was to determine the effect of an exogenous supply of GABA on tolerance to water stress in creeping bentgrass (Agrostis stolonifera), and further reveal the GABA-induced key mechanisms related to water balance, nitrogen (N) metabolism and nitric oxide (NO) production in response to water stress. Plants were pretreated with or without 0.5 mM GABA solution in the roots for 3 days, and then subjected to water stress induced by -0.52 MPa polyethylene glycol 6000 for 12 days. The results showed that water stress caused leaf water deficit, chlorophyll (Chl) loss, oxidative damage (increases in superoxide anion, hydrogen peroxide, malondialdehyde, and protein carbonyl content), N insufficiency, and metabolic disturbance. However, the exogenous addition of GABA significantly increased endogenous GABA content, osmotic adjustment and antioxidant enzyme activities (superoxide dismutase, catalase, dehydroascorbate reductase, glutathione reductase and monodehydroascorbate reductase), followed by effectively alleviating water stress damage, including declines in oxidative damage, photoinhibition, and water and Chl loss. GABA supply not only provided more available N, but also affected N metabolism through activating nitrite reductase and glutamine synthetase activities under water stress. The supply of GABA did not increase glutamate content and glutamate decarboxylase activity, but enhanced glutamate dehydrogenase activity, which might indicate that GABA promoted the conversion and utilization of glutamate for maintaining Chl synthesis and tricarboxylic acid cycle when creeping bentgrass underwent water stress. In addition, GABA-induced NO production, depending on nitrate reductase and NO-associated protein pathways, could be associated with the enhancement of antioxidant defense. Current findings reveal the critical role of GABA in regulating signal transduction and metabolic homeostasis in plants under water-limited condition.


Assuntos
Agrostis/fisiologia , Secas , Óxido Nítrico/metabolismo , Nitrogênio/metabolismo , Transdução de Sinais , Estresse Fisiológico , Água/metabolismo , Ácido gama-Aminobutírico/metabolismo , Adaptação Biológica , Estresse Oxidativo
19.
Molecules ; 25(18)2020 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-32961841

RESUMO

γ-Aminobutyric acid (GABA) participates in the regulation of adaptability to abiotic stress in plants. The objectives of this study were to investigate the effects of GABA priming on improving thermotolerance in creeping bentgrass (Agrostis stolonifera) based on analyses of physiology and proteome using iTRAQ technology. GABA-treated plants maintained significantly higher endogenous GABA content, photochemical efficiency, performance index on absorption basis, membrane stability, and osmotic adjustment (OA) than untreated plants during a prolonged period of heat stress (18 days), which indicated beneficial effects of GABA on alleviating heat damage. Protein profiles showed that plants were able to regulate some common metabolic processes including porphyrin and chlorophyll metabolism, glutathione metabolism, pyruvate metabolism, carbon fixation, and amino acid metabolism for heat acclimation. It is noteworthy that the GABA application particularly regulated arachidonic acid metabolism and phenylpropanoid biosynthesis related to better thermotolerance. In response to heat stress, the GABA priming significantly increased the abundances of Cu/ZnSOD and APX4 that were consistent with superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities. The GABA-upregulated proteins in relation to antioxidant defense (Cu/ZnSOD and APX4) for the reactive oxygen species scavenging, heat shock response (HSP90, HSP70, and HSP16.9) for preventing denatured proteins aggregation, stabilizing abnormal proteins, promoting protein maturation and assembly, sugars, and amino acids metabolism (PFK5, ATP-dependent 6-phosphofructokinase 5; FK2, fructokinase 2; BFRUCT, ß-fructofuranosidase; RFS2, galactinol-sucrose galactosyltransferase 2; ASN2, asparagine synthetase 2) for OA and energy metabolism, and transcription factor (C2H2 ZNF, C2H2 zinc-finger protein) for the activation of stress-defensive genes could play vital roles in establishing thermotolerance. Current findings provide an illuminating insight into the new function of GABA on enhancing adaptability to heat stress in plants.


Assuntos
Agrostis/metabolismo , Proteínas de Plantas/metabolismo , Proteoma/metabolismo , Proteômica/métodos , Estresse Fisiológico/efeitos dos fármacos , Termotolerância/efeitos dos fármacos , Ácido gama-Aminobutírico/farmacologia , Aminoácidos/metabolismo , Ascorbato Peroxidases/genética , Ascorbato Peroxidases/metabolismo , Ontologia Genética , Resposta ao Choque Térmico/efeitos dos fármacos , Redes e Vias Metabólicas/efeitos dos fármacos , Proteínas de Plantas/genética , Transdução de Sinais/efeitos dos fármacos , Superóxido Dismutase/genética , Superóxido Dismutase/metabolismo , Regulação para Cima/efeitos dos fármacos
20.
Plant Physiol Biochem ; 151: 181-187, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32224389

RESUMO

Turfgrasses are monocotyledonous plants from the family Poaceae. They are widely used in green spaces and are considered one of the most economically important horticultural crops in the world. Turfgrass quality is affected by several environmental factors including light, which is involved in the quality decline of transplanted sod. Ultraviolet-B (UV-B) is an important regulator of plant growth and development. Plants growing and/or stored in protected systems, such as in sod production, may be more vulnerable to UV-B damage than those growing in the field due to acclimation. Few studies on the effects of UV-B on turfgrass physiology have been published. Therefore, the aim of this study was to evaluate the influence of UV-B irradiation on the photosynthetic performance of five cool-season turfgrasses, namely Agrostis stolonifera L., Festuca arundinacea Schreb., Poa supina Schrad., Poa pratensis L. and Lolium perenne L. Turfgrasses were exposed to 18.25 kJ m-2 d-1 biologically effective UV-B in growth chambers under controlled conditions. Measurements included photosynthetic pigments, chlorophyll fluorescence and gas exchanges monitored for 16 d-UV-B treatment and after recovery. Content of pigments decreased with UV-B exposure with significant differences among the species. UV-B also affected the photosystem II (PSII) efficiency depending on the exposure period and species. Similarly, gas exchange parameters showed different effects among species after UV-B exposure compromising the assimilation of CO2. Multivariate analysis highlighted three main clusters of species confirming their different UV-B tolerance and ability to restore PSII photochemistry after recovery, from which Festuca arundinacea resulted to be the most tolerant.


Assuntos
Agrostis/fisiologia , Festuca/fisiologia , Lolium/fisiologia , Fotossíntese , Poa/fisiologia , Raios Ultravioleta , Clorofila , Complexo de Proteína do Fotossistema II
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