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1.
Environ Microbiol ; 22(3): 889-904, 2020 03.
Artículo en Inglés | MEDLINE | ID: mdl-31163094

RESUMEN

Root-associated microbial communities are important for maintaining agricultural productivity. However, belowground microbial community response to drought in temperate maize agroecosystems, as well as how these responses to water-stress are shaped by host genotype are poorly understood. Ten maize hybrids (six newer and four older) were grown in a replicated field trial. The endosphere, rhizosphere and soil bacterial and archaeal communities were sampled and analyzed using 16S rRNA gene amplicon sequencing. Sampling was done at two developmental stages in a water-limited environment with and without supplemental irrigation. Significant shifts in microbial community composition (ß-diversity) were measured between two sampling times during the season, in well-watered and water-stressed conditions and in newer and older generation maize hybrids. The microbial community diversity within samples (α-diversity) was not affected by drought stress or host factors. The phyla Actinobacteria and Firmicutes were more abundant in the rhizosphere of newer hybrids under water stress. These results highlight the importance of temporal variation, environmental stress and plant genetics as influenced by breeding history in shaping the composition of root associated microbial communities. These insights may provide new approaches to the improvement of crop stress tolerance through optimizing microbial communities.


Asunto(s)
Sequías , Microbiota/fisiología , Microbiología del Suelo , Zea mays/microbiología , Agricultura , Bacterias/genética , Microbiota/genética , Raíces de Plantas/microbiología , ARN Ribosómico 16S/genética , Rizosfera , Suelo/química , Estrés Fisiológico , Agua
2.
J Biol Chem ; 289(9): 5412-6, 2014 Feb 28.
Artículo en Inglés | MEDLINE | ID: mdl-24448804

RESUMEN

Cancer cells are characterized by elevated levels of reactive oxygen species, which are produced mainly by the mitochondria. The dismutase SOD2 localizes in the matrix and is a major antioxidant. The activity of SOD2 is regulated by the deacetylase SIRT3. Recent studies indicated that SIRT3 is decreased in 87% of breast cancers, implying that the activity of SOD2 is compromised. The resulting elevation in reactive oxygen species was shown to be essential for the metabolic reprograming toward glycolysis. Here, we show that SOD2 itself is down-regulated in breast cancer cell lines. Further, activation of oncogenes, such as Ras, promotes the rapid down-regulation of SOD2. Because in the absence of SOD2, superoxide levels are elevated in the matrix, we reasoned that mechanisms must exist to retain low levels of superoxide in other cellular compartments especially in the intermembrane space of the mitochondrial to avoid irreversible damage. The dismutase SOD1 also acts as an antioxidant, but it localizes to the cytoplasm and the intermembrane space of the mitochondria. We report here that loss of SOD2 correlates with the overexpression of SOD1. Further, we show that mitochondrial SOD1 is the main dismutase activity in breast cancer cells but not in non-transformed cells. In addition, we show that the SOD1 inhibitor LCS-1 leads to a drastic fragmentation and swelling of the matrix, suggesting that in the absence of SOD2, SOD1 is required to maintain the integrity of the organelle. We propose that by analogy to the cadherin switch during epithelial-mesenchymal transition, cancer cells also undergo a SOD switch during transformation.


Asunto(s)
Neoplasias de la Mama/enzimología , Transición Epitelial-Mesenquimal , Regulación Enzimológica de la Expresión Génica , Regulación Neoplásica de la Expresión Génica , Proteínas de Neoplasias/metabolismo , Superóxido Dismutasa/biosíntesis , Neoplasias de la Mama/genética , Neoplasias de la Mama/patología , Línea Celular Tumoral , Regulación hacia Abajo/efectos de los fármacos , Regulación hacia Abajo/genética , Inhibidores Enzimáticos/farmacología , Femenino , Humanos , Proteínas de Neoplasias/antagonistas & inhibidores , Proteínas de Neoplasias/genética , Sirtuina 3/genética , Sirtuina 3/metabolismo , Superóxido Dismutasa/antagonistas & inhibidores , Superóxido Dismutasa/genética , Superóxido Dismutasa-1 , Superóxidos/metabolismo
3.
Microorganisms ; 9(6)2021 Jun 18.
Artículo en Inglés | MEDLINE | ID: mdl-34207412

RESUMEN

The belowground microbiomes have many beneficial functions that assist plant growth, including nutrient cycling, acquisition and transport, as well as alleviation of stresses caused by nutrient limitations such as nitrogen (N). Here we analyzed the root endosphere, rhizosphere and soil bacterial communities of seven sweet sorghum genotypes differing in sensitivity to N-stress. Sorghum genotypes were grown in fields with no (low-N) or sufficient (high-N) N. The dry shoot weight ratio (low-N/high-N) was used to determine N-stress sensitivity. Our hypothesis was that genotypes tolerant and sensitive to N-stress select distinct bacterial communities. The endosphere and rhizosphere bacterial community structure were significantly different between the N-stress sensitive and tolerant genotypes in the high-N field, but not in the low-N field. However, significant changes in the relative abundance of specific bacterial taxa were observed in both fields. Streptomyces, a bacterial genus known to alleviate plant abiotic stresses, was enriched in the endosphere and rhizosphere of the tolerant genotypes in the low-N field. Our study indicates that sweet sorghum genotypes tolerant to N-stress select taxa that can potentially mitigate the N-stress, suggesting that the interactions between N-stress tolerant lines and the root-associated microbiome might be vital for coping with N-stress.

4.
J Exp Bot ; 61(12): 3395-405, 2010 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-20566566

RESUMEN

Recent reports suggest that early sensing of soil water stress by plant roots and the concomitant reduction in stomatal conductance may not be mediated by root-sourced abscisic acid (ABA), but that other xylem-borne chemicals may be the primary stress signal(s). To gain more insight into the role of root-sourced ABA, the timing and location of the expression of genes for key enzymes involved in ABA biosynthesis in Zea mays roots was measured and a comprehensive analysis of root xylem sap constituents from the early to the later stages of water stress was conducted. Xylem sap and roots were sampled from plants at an early stage of water stress when only a reduction in leaf conductance was measured, as well as at later stages when leaf xylem pressure potential decreased. It was found that the majority of ABA biosynthetic genes examined were only significantly expressed in the elongation region of roots at a later stage of water stress. Apart from ABA, sulphate was the only xylem-borne chemical that consistently showed significantly higher concentrations from the early to the later stages of stress. Moreover, there was an interactive effect of ABA and sulphate in decreasing maize transpiration rate and Vicia faba stomatal aperture, as compared to ABA alone. The expression of a sulphate transporter gene was also analysed and it was found that it had increased in the elongation region of roots from the early to the later stages of water stress. Our results support the suggestion that in the early stage of water stress, increased levels of ABA in xylem sap may not be due to root biosynthesis, ABA glucose ester catabolism or pH-mediated redistribution, but may be due to shoot biosynthesis and translocation to the roots. The analysis of xylem sap mineral content and bioassays indicate that the anti-transpirant effect of the ABA reaching the stomata at the early stages of water stress may be enhanced by the increased concentrations of sulphate in the xylem which is also transported from the roots to the leaves.


Asunto(s)
Ácido Abscísico/biosíntesis , Raíces de Plantas/metabolismo , Sulfatos/química , Xilema/química , Zea mays/química , Transporte Biológico , Deshidratación/metabolismo , Hojas de la Planta/metabolismo , Transpiración de Plantas , ARN de Planta/genética , Transducción de Señal , Suelo/análisis , Agua/metabolismo , Zea mays/enzimología , Zea mays/genética
5.
Plant Direct ; 3(3): e00122, 2019 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31245765

RESUMEN

Sorghum (Sorghum bicolor [L.] Moench) is the fifth most productive cereal crop worldwide with some hybrids having high biomass yield traits making it promising for sustainable, economical biofuel production. To maximize biofuel feedstock yields, a more complete understanding of metabolic responses to low nitrogen (N) will be useful for incorporation in crop improvement efforts. In this study, 10 diverse sorghum entries (including inbreds and hybrids) were field-grown under low and full N conditions and roots were sampled at two time points for metabolomics and 16S amplicon sequencing. Roots of plants grown under low N showed altered metabolic profiles at both sampling dates including metabolites important in N storage and synthesis of aromatic amino acids. Complementary investigation of the rhizosphere microbiome revealed dominance by a single operational taxonomic unit (OTU) in an early sampling that was taxonomically assigned to the genus Pseudomonas. Abundance of this Pseudomonas OTU was significantly greater under low N in July and was decreased dramatically in September. Correlation of Pseudomonas abundance with root metabolites revealed a strong negative association with the defense hormone salicylic acid (SA) under full N but not under low N, suggesting reduced defense response. Roots from plants with N stress also contained reduced phenylalanine, a precursor for SA, providing further evidence for compromised metabolic capacity for defense response under low N conditions. Our findings suggest that interactions between biotic and abiotic stresses may affect metabolic capacity for plant defense and need to be concurrently prioritized as breeding programs become established for biofuels production on marginal soils.

6.
Plant Cell Environ ; 31(3): 325-40, 2008 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-18088330

RESUMEN

Plants produce compounds in roots that are transported to shoots via the xylem sap. Some of these compounds are vital for signalling and adaptation to environmental stress such as drought. In this study, we screened the xylem sap using mass spectrometry to quantify the changes in new and previously identified sap constituents under extended drought. We detected and quantified the changes in the concentration of 31 compounds present in the xylem sap under progressively increasing drought stress. We found changes in the hormones abscisic acid (ABA) and cytokinin, and the presence of high concentrations of the aromatic cytokinin 6-benzylaminopurine (BAP). Several phenylpropanoid compounds (coumaric, caffeic and ferulic acids) were found in xylem sap. The concentrations of some of these phenylpropanoid compounds changed under drought. In parallel, an analysis of the xylem sap proteome was conducted. We found a higher abundance of cationic peroxidases, which with the increase in phenylpropanoids may lead to a reduction in lignin biosynthesis in the xylem vessels and could induce cell wall stiffening. The application of new methodologies provides insights into the range of compounds in sap and how alterations in composition may lead to changes in development and signalling during adaptation to drought.


Asunto(s)
Desastres , Regulación de la Expresión Génica de las Plantas , Proteínas de Plantas/metabolismo , Proteoma/metabolismo , Xilema/metabolismo , Zea mays/metabolismo , Células Cultivadas , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Concentración de Iones de Hidrógeno , Proteínas de Plantas/genética , Raíces de Plantas/metabolismo , Brotes de la Planta/metabolismo , Proteoma/genética , Proteómica , Transducción de Señal , Factores de Tiempo , Agua/metabolismo , Agua/farmacología , Xilema/efectos de los fármacos , Zea mays/efectos de los fármacos , Zea mays/genética
7.
J Vis Exp ; (137)2018 07 24.
Artículo en Inglés | MEDLINE | ID: mdl-30102263

RESUMEN

Plant and soil microbiome studies are becoming increasingly important for understanding the roles microorganisms play in agricultural productivity. The purpose of this manuscript is to provide detail on how to rapidly sample soil, rhizosphere, and endosphere of replicated field trials and analyze changes that may occur in the microbial communities due to sample type, treatment, and plant genotype. The experiment used to demonstrate these methods consists of replicated field plots containing two, pure, warm-season grasses (Panicum virgatum and Andropogon gerardii) and a low-diversity grass mixture (A. gerardii, Sorghastrum nutans, and Bouteloua curtipendula). Briefly, plants are excavated, a variety of roots are cut and placed in phosphate buffer, and then shaken to collect the rhizosphere. Roots are brought to the laboratory on ice and surface sterilized with bleach and ethanol (EtOH). The rhizosphere is filtered and concentrated by centrifugation. Excavated soil from around the root ball is placed into plastic bags and brought to the lab where a small amount of soil is taken for DNA extractions. DNA is extracted from roots, soil, and rhizosphere and then amplified with primers for the V4 region of the 16S rRNA gene. Amplicons are sequenced, then analyzed with open access bioinformatics tools. These methods allow researchers to test how the microbial community diversity and composition varies due to sample type, treatment, and plant genotype. Using these methods along with statistical models, the representative results demonstrate there are significant differences in microbial communities of roots, rhizosphere, and soil. Methods presented here provide a complete set of steps for how to collect field samples, isolate, extract, quantify, amplify, and sequence DNA, and analyze microbial community diversity and composition in replicated field trials.


Asunto(s)
Microbiota/genética , Raíces de Plantas/química , Plantas/genética , Poaceae/química , Rizosfera , Suelo/química , Bacterias/genética , Microbiología del Suelo
8.
Sci Rep ; 7(1): 15019, 2017 11 03.
Artículo en Inglés | MEDLINE | ID: mdl-29101364

RESUMEN

Rising atmospheric concentrations of CO2 and O3 are key features of global environmental change. To investigate changes in the belowground bacterial community composition in response to elevated CO2 and O3 (eCO2 and eO3) the endosphere, rhizosphere and soil were sampled from soybeans under eCO2 and maize under eO3. The maize rhizosphere and endosphere α-diversity was higher than soybean, which may be due to a high relative abundance of Rhizobiales. Only the rhizosphere microbiome composition of the soybeans changed in response to eCO2, associated with an increased abundance of nitrogen fixing microbes. In maize, the microbiome composition was altered by the genotype and linked to differences in root exudate profiles. The eO3 treatment did not change the microbial communities in the rhizosphere, but altered the soil communities where hybrid maize was grown. In contrast to previous studies that focused exclusively on the soil, this study provides new insights into the effects of plant root exudates on the composition of the belowground microbiome in response to changing atmospheric conditions. Our results demonstrate that plant species and plant genotype were key factors driving the changes in the belowground bacterial community composition in agroecosystems that experience rising levels of atmospheric CO2 and O3.


Asunto(s)
Dióxido de Carbono , Glycine max/genética , Ozono , Raíces de Plantas/microbiología , Rizosfera , Zea mays/genética , Microbiota/genética , Suelo , Microbiología del Suelo
9.
Plant Physiol ; 145(4): 1533-48, 2007 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-17951457

RESUMEN

Previous work on the adaptation of maize (Zea mays) primary roots to water deficit showed that cell elongation is maintained preferentially toward the apex, and that this response involves modification of cell wall extension properties. To gain a comprehensive understanding of how cell wall protein (CWP) composition changes in association with the differential growth responses to water deficit in different regions of the elongation zone, a proteomics approach was used to examine water soluble and loosely ionically bound CWPs. The results revealed major and predominantly region-specific changes in protein profiles between well-watered and water-stressed roots. In total, 152 water deficit-responsive proteins were identified and categorized into five groups based on their potential function in the cell wall: reactive oxygen species (ROS) metabolism, defense and detoxification, hydrolases, carbohydrate metabolism, and other/unknown. The results indicate that stress-induced changes in CWPs involve multiple processes that are likely to regulate the response of cell elongation. In particular, the changes in protein abundance related to ROS metabolism predicted an increase in apoplastic ROS production in the apical region of the elongation zone of water-stressed roots. This was verified by quantification of hydrogen peroxide content in extracted apoplastic fluid and by in situ imaging of apoplastic ROS levels. This response could contribute directly to the enhancement of wall loosening in this region. This large-scale proteomic analysis provides novel insights into the complexity of mechanisms that regulate root growth under water deficit conditions and highlights the spatial differences in CWP composition in the root elongation zone.


Asunto(s)
Aumento de la Célula , Pared Celular/metabolismo , Raíces de Plantas/metabolismo , Agua/fisiología , Zea mays/metabolismo , Adaptación Fisiológica , Electroforesis en Gel Bidimensional , Proteínas de Plantas/metabolismo , Raíces de Plantas/crecimiento & desarrollo , Proteoma/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Agua/metabolismo , Zea mays/crecimiento & desarrollo , Zea mays/fisiología
10.
J Proteome Res ; 5(4): 963-72, 2006 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-16602704

RESUMEN

The xylem in plants has mainly been described as a conduit for water and minerals, but emerging evidence also indicates that the xylem contains protein. To study the proteins in xylem sap, we characterized the identity and composition of the maize xylem sap proteome. The composition of the xylem sap proteome in maize revealed proteins related to different phases of xylem differentiation including cell wall metabolism, secondary cell wall synthesis, and programmed cell death. Many proteins were found to be present as multiple isoforms and some of these isoforms are glycosylated. Proteins involved in defense mechanisms were also present in xylem sap and the sap proteins were shown to have antifungal activity in bioassays.


Asunto(s)
Estructuras de las Plantas/química , Estructuras de las Plantas/fisiología , Proteoma/análisis , Zea mays/anatomía & histología , Zea mays/química , Antifúngicos/química , Antifúngicos/farmacología , Electroforesis en Gel Bidimensional , Glicosilación , Histocitoquímica , Nanotecnología , Neurospora crassa/efectos de los fármacos , Mapeo Peptídico , Extractos Vegetales/química , Proteínas de Plantas/análisis , Proteínas de Plantas/aislamiento & purificación , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Análisis de Secuencia de Proteína , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción , Tripsina/farmacología , Zea mays/crecimiento & desarrollo , Zea mays/fisiología
11.
J Exp Bot ; 56(419): 2389-400, 2005 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-16043455

RESUMEN

Many different techniques have been used for xylem sap collection, but few direct comparisons of techniques have been conducted and few comparisons have been based on comprehensive analyses of xylem sap. Moreover, the suitability of extraction techniques for use on plants grown under water-stress conditions has not been addressed. Xylem sap was extracted from both well-watered and water-stressed Zea mays plants using three different techniques. The main aim was to determine how the extraction method altered the correlations between sap constituents and stomatal conductance in order to determine which relationships change with extraction technique. A 'root pressure' technique was the simplest method of extracting large volumes of sap, but the low sap delivery rates altered the composition of sap. Two pressurization techniques that varied in the position from which sap was collected were tested. The pressurization techniques allowed for the control of delivery rates that influence sap constituent concentrations. The position from which xylem sap was collected on the plant was also found to be important. All three techniques produced consistent correlations between ABA and chloride delivery rates and changes in stomatal conductance, suggesting that each technique could be applied to identify certain putative xylem-borne signals.


Asunto(s)
Hojas de la Planta/fisiología , Estructuras de las Plantas/fisiología , Agua/fisiología , Zea mays/fisiología , Desecación , Concentración de Iones de Hidrógeno , Suelo/análisis , Zea mays/crecimiento & desarrollo
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