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1.
Chemosphere ; 262: 127865, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32791369

RESUMO

Chromium is a toxic heavy metal. Plants, animals and human metabolic processes are disturbed due to higher levels of chromium. PGPR are involved in seed germination, growth improvement, metabolic process and in most of the physiological processes of plants. Press mud in soil provides substrate to the microbes. PGPR can convert the more toxic form of Cr (VI) into less toxic form Cr (III). This study was conducted to find out the reduction potential of pre-isolated rhizobacteria and their role in strengthening of plant growth and physiological attributes. Soil collected from the research area was spiked with 20 mg kg-1 of Cr (VI) by using potassium dichromate (K2Cr2O7) salt before sowing. Results revealed that Cr (VI) significantly suppressed the shoot length, root length and photosynthetic rate of okra up to 19, 37 and 31%, respectively. However, inoculation decreases the uptake of Cr (VI) in root and shoot up to 37 and 31% and by press mud 33 and 20%, respectively. Combined application of inoculation and press mud significantly recovered the negative impact of chromium and plant growth was almost at par compared with contaminated treatment without inoculation.


Assuntos
Abelmoschus/crescimento & desenvolvimento , Cromo/análise , Poluentes do Solo/análise , Abelmoschus/metabolismo , Fotossíntese , Desenvolvimento Vegetal , Solo , Microbiologia do Solo
2.
Chemosphere ; 262: 127803, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32755694

RESUMO

Mine tailings pose a huge hazard for environmental and human health, and the establishment of vegetation cover is crucial to reduce pollutant dispersion for the surroundings. However, their hostile physicochemical conditions hamper plant growth, compromising phytoremediation strategies. This study aims to investigate the role of organo-mineral amendments and plant growth-promoting rhizobacteria (PGPR) on the improvement of mine tailings properties and Lolium perenne L. (ryegrass) growth. Plants were grown in mine tailings mixed with an agricultural soil (1:1), 10% compost, and supplied with two different inorganic amendments - rock phosphate (6%) or lime (3%), and inoculated with the rhizobacterial strains Advenellakashmirensis BKM20 (B1) and Mesorhizobium tamadayense BKM04 (B2). The application of organo-mineral amendments ameliorated tailings characteristics, which fostered plant growth and further enhanced soil fertility and microbial activity. These findings were consistent with the increase of total organic carbon levels, with the higher numbers of heterotrophic and phosphate solubilizing bacteria, and higher dehydrogenase and urease activities, found in these substrates after plant establishment. Plant growth was further boosted by PGPR inoculation, most noticeable by co-inoculation of both strains. Moreover, inoculated plants showed increased activities for several antioxidant enzymes (catalase, peroxidase, polyphenoloxidase, and glutathione reductase) which indicate a reinforced antioxidant system. The application of agricultural soil, compost and lime associated with the inoculation of a mixture of PGPR proved to enhance the establishment of vegetation cover, thus promoting the stabilization of Kettara mine tailings. Nonetheless, further studies are needed in order to confirm its effectiveness under field conditions.


Assuntos
Biodegradação Ambiental , Recuperação e Remediação Ambiental/métodos , Mesorhizobium/fisiologia , Desenvolvimento Vegetal , Poluentes do Solo/análise , Bactérias , Compostos de Cálcio , Lolium/crescimento & desenvolvimento , Minerais , Mineração , Óxidos , Solo/química
3.
Nat Commun ; 11(1): 5219, 2020 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-33060584

RESUMO

Nitrogen (N) is a macronutrient that boosts carbon (C) metabolism and plant growth leading to biomass accumulation. The molecular connection between nitrogen utilization efficiency (NUE) and biomass production remains unclear. Here, via quantitative trait loci analysis and map-based cloning, we reveal that natural variation at the MYB61 locus leads to differences in N use and cellulose biogenesis between indica and japonica subspecies of rice. MYB61, a transcriptional factor that regulates cellulose synthesis, is directly regulated by a known NUE regulator GROWTH-REGULATING FACTOR4 (GRF4), which coordinates cellulosic biomass production and N utilization. The variation at MYB61 has been selected during indica and japonica domestication. The indica allele of MYB61 displays robust transcription resulting in higher NUE and increased grain yield at reduced N supply than that of japonica. Our study hence unravels how C metabolism is linked to N uptake and may provide an opportunity to reduce N use for sustainable agriculture.


Assuntos
Nitrogênio/metabolismo , Oryza/crescimento & desenvolvimento , Oryza/genética , Oryza/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Alelos , Biomassa , Celulose/biossíntese , Grão Comestível/genética , Grão Comestível/metabolismo , Regulação da Expressão Gênica de Plantas , Variação Genética , Desenvolvimento Vegetal , Locos de Características Quantitativas , Transdução de Sinais , Transcrição Genética
4.
Yi Chuan ; 42(8): 739-751, 2020 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-32952110

RESUMO

Flowering is the adaptability of plants in response to the environment, which is regulated by the complex flowering control network formed by a variety of exogenous and endogenous signals. Plant hormones, the most important endogenous signal participants, play important roles in the process of plant flowering. Recent reports reveal the pivotal roles of hormones in the epigenetic regulation and flowering promotion pathway. In addition, synergistic or antagonistic interaction has been observed among many hormones. Numerous hormones have been found to be involved in the regulation of the multiple flowering development regulation and signaling pathways mediated by DELLA protein in the gibberellin (GA) pathway. In this review, we summarize the recent advances ofthe flowering mechanisms related to GA pathway and discuss the effects of abscisic acid (ABA), auxin (IAA), cytokinin (CTK), salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) on flowering, including their cross-regulation with DELLA, miRNAs, and transcription factor (TFs). This review provides a reference for further comprehensive analysis of the hormone-regulated network of plant flower formation.


Assuntos
Flores , Desenvolvimento Vegetal , Reguladores de Crescimento de Planta , Epigênese Genética , Flores/genética , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Humanos , MicroRNAs , Desenvolvimento Vegetal/genética , Reguladores de Crescimento de Planta/genética , Reguladores de Crescimento de Planta/metabolismo , Plantas/genética
5.
Ecotoxicol Environ Saf ; 205: 111350, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32961487

RESUMO

Atmospheric nitrogen dioxide (NO2) negatively affects plant (crop) growth and development, as well the yield and quality in some regions or environments. Arbuscular mycorrhizal fungus (AMF)-mediated amelioration of NO2-induced plant damage has been reported, but the underlying mechanisms remained unclear. This study explored the beneficial effect of AMF symbiosis on tomato plant responses to NO2 at physiology, biochemistry, and gene expression, with an emphasis on nitrate metabolism, antioxidative defense, and photosynthetic performance. Pot-grown plants were used in the experiments, which were performed in laboratory from February to November 2019. NO2 fumigation with a dose of 10 ± 1 ppm was carried out after 50 d of plant growth, and data were collected following 8 h of fumigation. NO2 fumigation (+NO2) and AMF inoculation (+AMF), alone and especially in combination (NO2 + AMF), increased the gene expression of nitrate- and nitrite reductase, and their enzymatic activity in leaves, such as by 61%, 27%, and 126% for the activity of nitrate reductase, and by 95%, 37%, and 188% for nitrite reductase, respectively, in +NO2, +AMF, and AMF + NO2 plants relative the control (-NO2, -AMF) levels. Following NO2 exposure, +AMF leaves displayed stronger activities of superoxide dismutase, peroxidase and catalase, and higher content of glutathione and ratio of its reduced form to oxidized form, as compared with -AMF ones. Correspondingly, lesser oxidative damage was detected in +AMF than in -AMF plants, as indicated by the contents of H2O2 and malondialdehyde, electrolyte leakage, also by in situ visualization for the formation of H2O2, superoxide anion, and dead cells. The increased antioxidative capacity in +AMF plants was correlated with enhanced expression of antioxidation-related genes. Exposure to NO2 substantially impaired photosynthetic processes in both + AMF and -AMF plants, but an obvious mitigation was observed in the former than in the latter. For example, the total chlorophyll, net photosynthetic rate, stomatal conductance, and ribulose-1,5-bisphosphate carboxylase activity were 18%, 27%, 26%, and 40% higher, respectively, in +AMF than in -AMF plants under NO2 stress. The differential photosynthetic performance was also revealed by chlorophyll fluorescence imaging. We analyzed the expression patterns of some genes related to photosynthesis and carbon metabolisms, and found that all of them exclusively presented a higher expression level in +AMF plants relative to -AMF ones under NO2 stress. Taken together, this study provided evidence that AMF symbiosis played a positively regulatory role in host plant responses to NO2, probably by increasing leaf nitrate metabolism and antioxidative defense, and maintaining the photosynthetic efficiency to some extent, wherein the transcription regulation might be a main target.


Assuntos
Lycopersicon esculentum/fisiologia , Micorrizas/fisiologia , Dióxido de Nitrogênio/toxicidade , Antioxidantes/metabolismo , Clorofila/metabolismo , Peróxido de Hidrogênio/metabolismo , Lycopersicon esculentum/metabolismo , Lycopersicon esculentum/microbiologia , Micorrizas/metabolismo , Oxirredução , Fotossíntese/fisiologia , Desenvolvimento Vegetal , Folhas de Planta/metabolismo
6.
Oecologia ; 194(1-2): 165-176, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32930886

RESUMO

Changes in resource availability can alter plant growth, the influence of plants on soil characteristics, and, ultimately, plant-soil feedback (PSF). Previous studies often show that invasive plants can outperform native plants under high but not low resource conditions. However, it remains unclear whether under low resource conditions, invaders can outperform natives in the long term by generating more positive or less negative PSFs. Using three non-native invasive and three non-invasive native annual Asteraceae plants, we conducted a two-phase pot experiment, where in the first, conditioning generation plants were grown to induce changes in soil characteristics, and in the second, bioassay generation plants were regrown to evaluate how they respond to these soils. Half of the pots received a nutrient addition treatment in the conditioning generation. We found significant species-specific effects of conditioning on most of the soil characteristics, and some soil characteristics were significantly correlated with bioassay generation biomass of a subset of species, but neither species nor invasive or native status affected bioassay generation biomass. All invasive species generated neutral PSFs across soil nutrient conditions. The native Emilia sonchifolia tended to condition the soil that favored its own growth more than others, and under low nutrient conditions, the native Eclipta prostrata conditioned the soil that disfavored its own growth more than others. These results indicate that invaders may not outperform natives through PSFs under low resource conditions, and increasing resource availability may change the types of PSFs for some native but not invasive plants.


Assuntos
Asteraceae , Solo , Biomassa , Espécies Introduzidas , Desenvolvimento Vegetal
7.
Nat Commun ; 11(1): 4621, 2020 09 22.
Artigo em Inglês | MEDLINE | ID: mdl-32963240

RESUMO

Arctic warming can influence tundra ecosystem function with consequences for climate feedbacks, wildlife and human communities. Yet ecological change across the Arctic tundra biome remains poorly quantified due to field measurement limitations and reliance on coarse-resolution satellite data. Here, we assess decadal changes in Arctic tundra greenness using time series from the 30 m resolution Landsat satellites. From 1985 to 2016 tundra greenness increased (greening) at ~37.3% of sampling sites and decreased (browning) at ~4.7% of sampling sites. Greening occurred most often at warm sampling sites with increased summer air temperature, soil temperature, and soil moisture, while browning occurred most often at cold sampling sites that cooled and dried. Tundra greenness was positively correlated with graminoid, shrub, and ecosystem productivity measured at field sites. Our results support the hypothesis that summer warming stimulated plant productivity across much, but not all, of the Arctic tundra biome during recent decades.


Assuntos
Ecossistema , Estações do Ano , Tundra , Regiões Árticas , Mudança Climática , Monitoramento Ambiental , Desenvolvimento Vegetal , Plantas , Solo , Temperatura
8.
Sci Total Environ ; 747: 141274, 2020 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-32791411

RESUMO

This study was conducted to estimate the influence of composted rice straw (CRS) on the growth and nutritional composition of purple cabbage (Brassica oleracea L. var. capitate L.). In order to select the proper preparation method of CRS based media, growing media were prepared by mixing peat, perlite, vermiculite and sand with CRS in different ratios. The general proportions of CRS in substrates were 25% and 50% (v/v). A mixture of 50% peat with 50% perlite (v/v) was the control (CK). Completely randomized design was used in the experiment under greenhouse conditions. The physicochemical characteristics of all growing media were determined before transplanting. Plant growth parameters as well as the mineral elements were also measured. In general, plants grown in most CRS based media were improved in growth and element nutrition in comparison with control. 25% CRS addition was the most-suitable rate for the growth of purple cabbage. The highest leaves yield obtained from T3 (25% CRS: 25% peat: 50% vermiculite, v:v:v) increased by 105.99% compared to control. CRS can be an alternative constituent to replace the generally using peat in growing media.


Assuntos
Brassica , Compostagem , Oryza , Desenvolvimento Vegetal , Solo
9.
Ecotoxicol Environ Saf ; 204: 111020, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32810706

RESUMO

Over the past 30 years, the ever-rising demands of the modern and growing population have led to the rapid development of agricultural and industrial sectors worldwide. However, this expansion has exposed the environment to various pollutants including heavy metal (HM)s. Almost all HMs are serious toxicants and can pose serious health risks to living organisms in addition to their bioaccumulative and non-biodegradable nature. Different techniques have been developed to restore the ecological functions of the HM-contaminated soil (HMCS). However, the major downfalls of the commonly used remediation technologies are the generation of secondary wastes, high operating costs, and high energy consumption. Phytoremediation is a prominent approach that is more innocuous than the existing remediation approaches. Some microbes-plant interactions enhance the bioremediation process, with heavy metal resistant-plant growth promoting bacteria (HMRPGPB) being widely used to assist phytoremediation of HMs. However, the most common of all major microbial assisted-phytoremediation disturbances is that the HM-contaminated soil is generally deficient in nutrients and cannot sustain the rapid growth of the applied HMRPGPB. In this case, biochar has recently been approved as a potential carrier of microbial agents. The biochar-HMRPGPB-plant association could provide a promising green approach to remediate HM-polluted sites. Therefore, this review addresses the mechanisms through which biochar and HMRPGPB can enhance phytoremediation. This knowledge of biochar-HMRPGPB-plant interactions is significant with respect to sustainable management of the HM-polluted environment in terms of both ecology and economy, and it offers the possibility of further development of new green technologies.


Assuntos
Bactérias/metabolismo , Biodegradação Ambiental , Carvão Vegetal/farmacologia , Embriófitas/metabolismo , Metais Pesados/metabolismo , Poluentes do Solo/metabolismo , Desenvolvimento Vegetal/efeitos dos fármacos , Desenvolvimento Vegetal/fisiologia , Solo/química
10.
Proc Natl Acad Sci U S A ; 117(35): 21747-21756, 2020 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-32817425

RESUMO

Arabidopsis AINTEGUMENTA (ANT), an AP2 transcription factor, is known to control plant growth and floral organogenesis. In this study, our transcriptome analysis and in situ hybridization assays of maize embryonic leaves suggested that maize ANT1 (ZmANT1) regulates vascular development. To better understand ANT1 functions, we determined the binding motif of ZmANT1 and then showed that ZmANT1 binds the promoters of millet SCR1, GNC, and AN3, which are key regulators of Kranz anatomy, chloroplast development, and plant growth, respectively. We generated a mutant with a single-codon deletion and two frameshift mutants of the ANT1 ortholog in the C4 millet Setaria viridis by the CRISPR/Cas9 technique. The two frameshift mutants displayed reduced photosynthesis efficiency and growth rate, smaller leaves, and lower grain yields than wild-type (WT) plants. Moreover, their leaves sporadically exhibited distorted Kranz anatomy and vein spacing. Conducting transcriptomic analysis of developing leaves in the WT and the three mutants we identified differentially expressed genes (DEGs) in the two frameshift mutant lines and found many down-regulated DEGs enriched in photosynthesis, heme, tetrapyrrole binding, and antioxidant activity. In addition, we predicted many target genes of ZmANT1 and chose 13 of them to confirm binding of ZmANT1 to their promoters. Based on the above observations, we proposed a model for ANT1 regulation of cell proliferation and leaf growth, vascular and vein development, chloroplast development, and photosynthesis through its target genes. Our study revealed biological roles of ANT1 in several developmental processes beyond its known roles in plant growth and floral organogenesis.


Assuntos
Translocador 1 do Nucleotídeo Adenina/metabolismo , Zea mays/crescimento & desenvolvimento , Zea mays/genética , Translocador 1 do Nucleotídeo Adenina/fisiologia , Sistemas de Transporte de Aminoácidos Neutros/genética , Sistemas de Transporte de Aminoácidos Neutros/metabolismo , Cloroplastos/metabolismo , Flores/genética , Flores/crescimento & desenvolvimento , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas/genética , Milhetes/genética , Milhetes/metabolismo , Organogênese Vegetal/genética , Fotossíntese/genética , Fotossíntese/fisiologia , Desenvolvimento Vegetal/genética , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Fatores de Transcrição/metabolismo , Transcriptoma
11.
Proc Natl Acad Sci U S A ; 117(35): 21757-21765, 2020 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-32817510

RESUMO

An evolutionarily ancient plant hormone receptor complex comprising the α/ß-fold hydrolase receptor KARRIKIN INSENSITIVE 2 (KAI2) and the F-box protein MORE AXILLARY GROWTH 2 (MAX2) mediates a range of developmental responses to smoke-derived butenolides called karrikins (KARs) and to yet elusive endogenous KAI2 ligands (KLs). Degradation of SUPPRESSOR OF MAX2 1 (SMAX1) after ligand perception is considered to be a key step in KAR/KL signaling. However, molecular events which regulate plant development downstream of SMAX1 removal have not been identified. Here we show that Lotus japonicus SMAX1 is specifically degraded in the presence of KAI2 and MAX2 and plays an important role in regulating root and root hair development. smax1 mutants display very short primary roots and elongated root hairs. Their root transcriptome reveals elevated ethylene responses and expression of ACC Synthase 7 (ACS7), which encodes a rate-limiting enzyme in ethylene biosynthesis. smax1 mutants release increased amounts of ethylene and their root phenotype is rescued by treatment with ethylene biosynthesis and signaling inhibitors. KAR treatment induces ACS7 expression in a KAI2-dependent manner and root developmental responses to KAR treatment depend on ethylene signaling. Furthermore, in Arabidopsis, KAR-induced root hair elongation depends on ACS7 Thus, we reveal a connection between KAR/KL and ethylene signaling in which the KAR/KL signaling module (KAI2-MAX2-SMAX1) regulates the biosynthesis of ethylene to fine-tune root and root hair development, which are important for seedling establishment at the beginning of the plant life cycle.


Assuntos
Proteínas de Arabidopsis/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Lotus/metabolismo , Raízes de Plantas/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Transporte/metabolismo , Etilenos/biossíntese , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Germinação/fisiologia , Hidrolases/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/genética , Lotus/genética , Liases/genética , Liases/metabolismo , Organogênese Vegetal/genética , Desenvolvimento Vegetal/genética , Reguladores de Crescimento de Planta/metabolismo , Plântula/metabolismo , Transdução de Sinais/efeitos dos fármacos
12.
Trends Plant Sci ; 25(10): 954-958, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32736923

RESUMO

Despite increasing understanding of 5-methylcytosine (m5C) on RNAs in mammals, the function of m5C in plants remains obscure. A dynamic function of m5C in plant development and stress adaptation had been suggested, and Tang et al. have now uncovered a role for RNA m5C methyltransferase in rice adaptation to high temperature.


Assuntos
Oryza , 5-Metilcitosina , Animais , Oryza/genética , Desenvolvimento Vegetal , RNA , RNA Mensageiro , Temperatura
13.
Arch Microbiol ; 202(10): 2739-2749, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32737540

RESUMO

The signal orchestration between legumes and the rhizobia attribute to symbiotic nitrogen fixation through nodule formation. Root nodules serve as a nutrient-rich reservoir and harbor diverse microbial communities. However, the existence of non-rhizobial endophytes (NRE) and their role inside the root nodules are being explored; there is no evidence on yeast microflora inhabiting nodule niche. This study focused on unraveling the presence of yeast in the root nodules and their possible function in either nodulation or signal exchange. From the root nodules of blackgram, two yeast strains were isolated and identified as Candida glabrata VYP1 and Candida tropicalis VYW1 based on 18S rRNA gene sequencing and phylogeny. These strains possessed plant growth-promoting traits viz., IAA, ACC deaminase, siderophore, ammonia, and polyamine production. The functional capacity of endophytic yeast strains, and their interaction with Rhizobium sp. was further unveiled via profiling volatile organic compounds (VOC). Among the VOCs, α-glucopyranoside and pyrroloquinoline pitches a pivotal role in activating lectin pathways and phosphorous metabolism. Further, lectin pathways are crucial for nodulating bacterium, and our study showed that these endophytic yeasts assist nodulation by Rhizobium sp. via activating the nod factors. The plant growth-promoting traits of NRE yeast strains coupled with their metabolite production, could recruit them as potential drivers in the plant-microbe interaction.


Assuntos
Candida glabrata/isolamento & purificação , Candida tropicalis/isolamento & purificação , Endófitos/isolamento & purificação , Vigna/microbiologia , Compostos Orgânicos Voláteis/análise , Candida glabrata/genética , Candida tropicalis/genética , Carbono-Carbono Liases , Endófitos/classificação , Interações Microbianas , Fixação de Nitrogênio/fisiologia , Filogenia , Desenvolvimento Vegetal , Nodulação , Pirróis/análise , Quinolinas/análise , Rhizobium/fisiologia , Nódulos Radiculares de Plantas/microbiologia , Simbiose/fisiologia
14.
J Environ Manage ; 273: 111118, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32741760

RESUMO

The concept of soil health refers to specific soil properties and the ability to support and sustain crop growth and productivity, while maintaining long-term environmental quality. The key components of healthy soil are high populations of organisms that promote plant growth, such as the plant growth promoting rhizobacteria (PGPR). PGPR plays multiple beneficial and ecological roles in the rhizosphere soil. Among the roles of PGPR in agroecosystems are the nutrient cycling and uptake, inhibition of potential phytopathogens growth, stimulation of plant innate immunity, and direct enhancement of plant growth by producing phytohormones or other metabolites. Other important roles of PGPR are their environmental cleanup capacities (soil bioremediation). In this work, we review recent literature concerning the diverse mechanisms of PGPR in maintaining healthy conditions of agricultural soils, thus reducing (or eliminating) the toxic agrochemicals dependence. In conclusion, this review provides comprehensive knowledge on the current PGPR basic mechanisms and applications as biocontrol agents, plant growth stimulators and soil rhizoremediators, with the final goal of having more agroecological practices for sustainable agriculture.


Assuntos
Desenvolvimento Vegetal , Solo , Agricultura , Raízes de Plantas , Rizosfera , Microbiologia do Solo
15.
Sci Total Environ ; 743: 140682, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32758827

RESUMO

New eco-friendly approaches are required to improve plant biomass production. Beneficial plant growth-promoting (PGP) bacteria may be exploited as excellent and efficient biotechnological tools to improve plant growth in various - including stressful - environments. We present an overview of bacterial mechanisms which contribute to plant health, growth, and development. Plant growth promoting rhizobacteria (PGPR) can interact with plants directly by increasing the availability of essential nutrients (e.g. nitrogen, phosphorus, iron), production and regulation of compounds involved in plant growth (e.g. phytohormones), and stress hormonal status (e.g. ethylene levels by ACC-deaminase). They can also indirectly affect plants by protecting them against diseases via competition with pathogens for highly limited nutrients, biocontrol of pathogens through production of aseptic-activity compounds, synthesis of fungal cell wall lysing enzymes, and induction of systemic responses in host plants. The potential of PGPR to facilitate plant growth is of fundamental importance, especially in case of abiotic stress, where bacteria can support plant fitness, stress tolerance, and/or even assist in remediation of pollutants. Providing additional evidence and better understanding of bacterial traits underlying plant growth-promotion can inspire and stir up the development of innovative solutions exploiting PGPR in times of highly variable environmental and climatological conditions.


Assuntos
Desenvolvimento Vegetal , Reguladores de Crescimento de Planta , Bactérias , Plantas , Microbiologia do Solo , Estresse Fisiológico
16.
Ann Bot ; 126(4): 687-699, 2020 09 14.
Artigo em Inglês | MEDLINE | ID: mdl-32756867

RESUMO

BACKGROUND AND AIMS: Using internal trophic pressure as a regulating variable to model the complex interaction loops between organogenesis, production of assimilates and partitioning in functional-structural models of plant growth has attracted increasing interest in recent years. However, this approach is hampered by the fact that internal trophic pressure is a non-measurable quantity that can be assessed only through model parametric estimation, for which the methodology is not straightforward, especially when the model is stochastic. METHODS: A stochastic GreenLab model of plant growth (called 'GL4') is developed with a feedback effect of internal trophic competition, represented by the ratio of biomass supply to demand (Q/D), on organogenesis. A methodology for its parameter estimation is presented and applied to a dataset of 15 two-year-old Coffea canephora trees. Based on the fitting results, variations in Q/D are reconstructed and analysed in relation to the estimated variations in organogenesis parameters. KEY RESULTS: Our stochastic retroactive model was able to simulate realistically the progressive set-up of young plant architecture and the branch pruning effect. Parameter estimation using real data for Coffea trees provided access to the internal trophic dynamics. These dynamics correlated with the organogenesis probabilities during the establishment phase. CONCLUSIONS: The model can satisfactorily reproduce the measured data, thus opening up promising avenues for further applying this original procedure to other experimental data. The framework developed can serve as a model-based toolkit to reconstruct the hidden internal trophic dynamics of plant growth.


Assuntos
Coffea , Desenvolvimento Vegetal , Biomassa , Simulação por Computador , Modelos Biológicos
17.
Ecotoxicol Environ Saf ; 205: 111145, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32846296

RESUMO

This study characterizes sunflower response to the levels of Cd encountered in moderately Cd-polluted soils. Two sunflower cultivars differing in their ability to sequestrate Cd in roots were exposed to low concentrations of Cd (0.5 nM or 100 nM) in hydroponics and sampled after 18 days (258 degree-days) when ten leaves were fully expanded. Plant growth, Cd uptake and partitioning among organs were monitored along with the ionomic (ICP-MS) and the metabolic (1H-NMR) composition of the xylem sap. Sunflower tolerance to Cd differed between the two cultivars. The cultivar with the highest ability to sequestrate Cd in roots (Kapllan) was more tolerant to Cd than the one with the lowest ability (ES RICA). The 23% penalization of plant growth observed at 100 nM in cultivar ES RICA was associated with reduced xylem loading fluxes of soluble sugars, perhaps pointing to disruption of carbohydrate metabolism. Retention of Cd in the stem was higher at 100 nM than at 0.5 nM in the Cd-sensitive cultivar ES RICA, which can be seen as a sunflower strategy to restrict the amount of Cd delivered to the leaves under Cd stress. No direct connection was found between the speciation of Cd in the xylem sap and the Cd translocation efficiency, although significant changes in the free ionic fraction of Cd were observed between the two cultivars at 0.5 nM. The relevance of these results in promoting the use of sunflower in phytomanagement of Cd-polluted soils is discussed.


Assuntos
Cádmio/metabolismo , Helianthus/metabolismo , Hidroponia , Transporte Biológico , Desenvolvimento Vegetal , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Xilema/metabolismo
18.
J Environ Manage ; 275: 111230, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32861001

RESUMO

Internal green wall systems can be combined with building structures to bring positive impacts on people's quality of life in interior spaces. However, obtaining green wall systems to optimize the performances of these living walls still needs research works. This study was conducted to investigate the plant, and air-quality performance resulted from combining ornamental plants and growing media types in an internal green wall system. The growing media types (mixed based on volume percentage) included cocopeat, perlite, cocopeat + perlite (1v:1v) and cocopeat + perlite + vermicompost (1v:1v:1v). The ornamental species included Peperomia magnoliiaefolia, Kalanchoe blossfeldiana, Aptenia cordifolia, and Carpobrotus edulis. There were significant differences among the plant species and the growing media types for improvement of the plant growth and morphophysiological factors. Organic-rich growing media of vermicompost along with perlite and cocopeat, combined with Aptenia cordifolia as the species can be used to create a horticulturally sustainable internal green wall, and also improve the health index in the building interior environments.


Assuntos
Poluição do Ar , Qualidade de Vida , Hidroponia , Desenvolvimento Vegetal , Plantas
19.
PLoS One ; 15(8): e0234166, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32797098

RESUMO

Response to simultaneous stressors is an important facet of plant ecology and land management. In a greenhouse trial, we studied how eight plant species responded to single and combined effects of three soil concentrations of the phytotoxic munitions constituent RDX and two levels of water-resourcing. In an outdoor trial, we studied the effects of high RDX soil concentration and two levels of water-resourcing in three plant species. Multiple endpoints related to RDX fate, plant health, and plant survival were evaluated in both trials. Starting RDX concentration was the most frequent factor influencing all endpoints. Water-resourcing also had significant impacts, but in fewer cases. For most endpoints, significant interaction effects between RDX concentration and water-resourcing were observed for some species and treatments. Main and interaction effects were typically variable (significant in one treatment, but not in another; associated with increasing endpoint values for one treatment and/or with decreasing endpoint values in another). This complexity has implications for understanding how RDX and water-availability combine to impact plants, as well as for applications like phytoremediation. As an additional product of these greenhouse and outdoor trials, three plants native or naturalized within the southeastern United States were identified as promising species for further study as in situ phytoremediation resources. Plumbago auriculata exhibited relatively strong and markedly consistent among-treatment mean proportional reductions in soil RDX concentrations (112% and 2.5% of the means of corresponding values observed within other species). Likewise, across all treatments, Salvia coccinea exhibited distinctively low variance in mean leaf chlorophyll content index levels (6.5% of the means of corresponding values observed within other species). Both species also exhibited mean wilting and chlorosis levels that were 66% and 35%, and 67% and 84%, of corresponding values observed in all other plants, respectively. Ruellia caroliniensis exhibited at least 43% higher mean survival across all treatments than any other test species in outdoor trials, despite exhibiting similar RDX uptake and bioconcentration levels.


Assuntos
Substâncias Explosivas/toxicidade , Plantas/efeitos dos fármacos , Poluentes do Solo/toxicidade , Triazinas/toxicidade , Acanthaceae/efeitos dos fármacos , Acanthaceae/crescimento & desenvolvimento , Acanthaceae/fisiologia , Biodegradação Ambiental , Substâncias Explosivas/administração & dosagem , Substâncias Explosivas/farmacocinética , Instalações Militares , Desenvolvimento Vegetal/efeitos dos fármacos , Fenômenos Fisiológicos Vegetais/efeitos dos fármacos , Plumbaginaceae/efeitos dos fármacos , Plumbaginaceae/crescimento & desenvolvimento , Plumbaginaceae/fisiologia , Salvia/efeitos dos fármacos , Salvia/crescimento & desenvolvimento , Salvia/fisiologia , Poluentes do Solo/administração & dosagem , Poluentes do Solo/farmacocinética , Sudeste dos Estados Unidos , Estresse Fisiológico/efeitos dos fármacos , Triazinas/administração & dosagem , Poluentes Químicos da Água/administração & dosagem , Poluentes Químicos da Água/farmacocinética , Poluentes Químicos da Água/toxicidade , Recursos Hídricos
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