- Mexico City, Mexico City, Mexico
<p>The expression levels of a battery of genes involved in C and N metabolism and transport were measured in roots (<b>A</b>), and leaves (<b>B</b>), of <i>A. cruentus</i> plants inoculated with... more
<p>The expression levels of a battery of genes involved in C and N metabolism and transport were measured in roots (<b>A</b>), and leaves (<b>B</b>), of <i>A. cruentus</i> plants inoculated with <i>Burkholderia caribensis</i> XV. The relative expression levels were determined by qPCR at 3, 5 and 7 weeks after seed inoculation, using the 2<sup>−ΔΔCt</sup> method, as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088094#pone.0088094-Livak1" target="_blank">[94]</a>. The bars represent mean values ± SE. Dashed lines indicate upper and lower limits beyond which genes were considered to be up- and down-regulated, respectively. Experiments were performed thrice, and results from a representative experiment are shown.</p
Research Interests: Biochemistry, Microbiology, Agronomy, Plant Ecology, Genomics, and 15 moreMetabolism, Ecology, Agricultural Biotechnology, Medicine, Plant Science, Gene expression, Biological Sciences, PCR, Crops, Plant Biochemistry, Nitrogen metabolism, Agricultural Production, Cereals, Molecular Cell Biology, and Plant Growth and Development
<p>Relative expression levels<sup>2</sup> were determined in leaves, stems and roots of <i>A. hypochondriacus</i> plants, with contrasting pigmentation patterns, subjected to salt stress. Induced or repressed... more
<p>Relative expression levels<sup>2</sup> were determined in leaves, stems and roots of <i>A. hypochondriacus</i> plants, with contrasting pigmentation patterns, subjected to salt stress. Induced or repressed levels of expression (i.e. relative expression ≥1.5 or ≤0.5) are shown in bold text and italics, respectively.</p>1<p>The genotypes examined in this study were <i>Ah</i> cv. Nutrisol (<i>AhNut</i>; with predominantly betacyanic leaves), <i>Ah</i> India Red (<i>AhIR</i>; with predominantly betacyanic stems) and <i>Ah</i> India Green (<i>AhIG</i>; with all tissues acyanic).</p>2<p>The fold change in the expression of the target genes was calculated using the 2<sup>−ΔΔCt</sup> method according to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0099012#pone.0099012-Livak1" target="_blank">[76]</a>.</p
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<p>Real-time quantitative polymerase chain reaction analysis of the basal expression of 5 betacyanin biosynthetic genes in <b>(A)</b> leaves, <b>(B)</b> stems and <b>(C)</b> roots of three... more
<p>Real-time quantitative polymerase chain reaction analysis of the basal expression of 5 betacyanin biosynthetic genes in <b>(A)</b> leaves, <b>(B)</b> stems and <b>(C)</b> roots of three genotypes of <i>A. hypochondriacus</i> plants differing in their pigmentation patterns, as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0099012#pone-0099012-g001" target="_blank">Figure 1</a>. The genes analyzed were the following: a UDP-glucose: cyclo-DOPA 5-O glucosyltransferase (<i>cD5-GT</i>), two 4, 5-DOPA-extradiol-dioxygenase genes (<i>DODA-1</i> and <i>DODA-2</i>), a UDP-glucose: betanidin 5-<i>O</i>-glucosyltransferase (<i>B5-GT</i>), and an ortholog of the red beet cytochrome P-450 <i>R</i> gene (<i>CYP76</i>). Transcript levels of these genes were normalized using <i>A. hypochondricus</i> actin and tubulin, as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0099012#pone.0099012-Yuan1" target="_blank">[77]</a>. Data are means ± SE (n = 6). Different letters over the bars represent statistically different values at <i>P</i>≤0.05 (Tukey Kramer test). FW = fresh weight.</p
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<p>ND = Not determined.</p>1<p> = Described in Reference <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088094#pone.0088094-delosSantosVillalobos1"... more
<p>ND = Not determined.</p>1<p> = Described in Reference <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088094#pone.0088094-delosSantosVillalobos1" target="_blank">[37]</a>;</p>2<p> = Described in reference <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088094#pone.0088094-JimnezDelgadillo1" target="_blank">[91]</a>;</p>3<p> = Described in Reference <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088094#pone.0088094-delosSantosVillalobos2" target="_blank">[92]</a>.</p
Research Interests: Biochemistry, Microbiology, Agronomy, Plant Ecology, Genomics, and 15 moreMetabolism, Ecology, Agricultural Biotechnology, Medicine, Plant Science, Gene expression, Biological Sciences, Crops, Plant Biochemistry, Nitrogen metabolism, Agricultural Production, Cereals, Molecular Cell Biology, Rhizobacteria, and Plant Growth and Development
Systemin (Sys) is an octadecapeptide which, upon wounding, is released from the carboxy terminus of its precursor, prosystemin(ProSys) to promote plant defenses. Recent findings on the disordered structure of ProSysprompted us to... more
Systemin (Sys) is an octadecapeptide which, upon wounding, is released from the carboxy terminus of its precursor, prosystemin(ProSys) to promote plant defenses. Recent findings on the disordered structure of ProSysprompted us to investigate a putative biological role of the whole precursor deprived of Sys peptide. We produced transgenic tomato plants expressing a truncated ProSys gene in which the exon coding for Sys was removed and compared their defense response with that induced by the exogenous application of the recombinant deleted ProSys[ProSys(1-178)].By combining protein structure analyses, transcriptomic analysis, gene expression profiling and bioassays with different pests we demonstrate that the truncated ProSys, that does not induce the endogenous ProSys gene, promotes defense barriers in tomato plants through a hormone independent defense pathway, likely associated with the production of oligogalacturonides (OGs). Both transgenic and plants treated with the recombinant...
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A suppression‐subtractive‐hybridization (SSH) strategy was used to identify genes whose expression was modified in response to virus‐free whitefly Bemisia tabaci (Bt, biotype A) infestation in tomato (Solanum lycopersicum) plants. Thus,... more
A suppression‐subtractive‐hybridization (SSH) strategy was used to identify genes whose expression was modified in response to virus‐free whitefly Bemisia tabaci (Bt, biotype A) infestation in tomato (Solanum lycopersicum) plants. Thus, forward and reverse SSH gene libraries were generated at four points in the whitefly's life cycle, namely at (1) 2 days (adult feeding and oviposition: phase I); (2) 7 days (mobile crawler stage: phase II); (3) 12 days (second to third instar nymphal transition: phase III) and (4) 18 days (fourth instar nymphal stage: phase IV). The 169 genes with altered expression (up and downregulated) that were identified in the eight generated SSH libraries, together with 75 additional genes that were selected on the basis of their involvement in resistance responses against phytofagous insects and pathogens, were printed on a Nexterion® Slide MPX 16 to monitor their pattern of expression at the above phases. The results indicated that Bt infestation in toma...
Research Interests: Botany, Plant Biology, Biology, Medicine, Gene expression, and 15 morePlant diseases, Animals, Life Cycle, Tomato, Hemiptera, Infestation, Solanum, Bemisia tabaci, Solanum Lycopersicum, Differential Gene Expression, Lycopersicon esculentum, Biochemistry and cell biology, Physiologia, Horticultural production, and Stress Physiological
Background Amaranthus cruentus and A. hypochondriacus are crop plants grown for grain production in subtropical countries. Recently, the generation of large-scale transcriptomic data opened the possibility to study representative genes of... more
Background Amaranthus cruentus and A. hypochondriacus are crop plants grown for grain production in subtropical countries. Recently, the generation of large-scale transcriptomic data opened the possibility to study representative genes of primary metabolism to gain a better understanding of the biochemical mechanisms underlying tolerance to defoliation in these species. A multi-level approach was followed involving gene expression analysis, enzyme activity and metabolite measurements. Results Defoliation by insect herbivory (HD) or mechanical damage (MD) led to a rapid and transient reduction of non-structural carbohydrates (NSC) in all tissues examined. This correlated with a short-term induction of foliar sucrolytic activity, differential gene expression of a vacuolar invertase and its inhibitor, and induction of a sucrose transporter gene. Leaf starch in defoliated plants correlated negatively with amylolytic activity and expression of a β-amylase-1 gene and positively with a sol...
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2007 Miriam Tejeda Sartorius / Norma Angélica Martínez Gallardo / Víctor Olalde Portugal / John Paul Délano Frier JASMONIC ACID ACCELERATES THE EXPRESSION OF A PATHOGEN-SPECIFIC LIPOXYGENASE (POTLX-3) AND DELAYS FOLIAR LATE BLIGHT... more
2007 Miriam Tejeda Sartorius / Norma Angélica Martínez Gallardo / Víctor Olalde Portugal / John Paul Délano Frier JASMONIC ACID ACCELERATES THE EXPRESSION OF A PATHOGEN-SPECIFIC LIPOXYGENASE (POTLX-3) AND DELAYS FOLIAR LATE BLIGHT DEVELOPMENT IN ...
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At world level, Mexico is located as an important participant in fresh mango production and trade, standing out as producer (2∗106 t year-1) and exporter (2∗105 t year-1) of mango and importer of minimum quantities with regard to its... more
At world level, Mexico is located as an important participant in fresh mango production and trade, standing out as producer (2∗106 t year-1) and exporter (2∗105 t year-1) of mango and importer of minimum quantities with regard to its production and export. The economic activity around mango, is integrated by a group of stages that goes from fruit production to its consumption, which has been called value chain of mango; with base in scientific and empiric knowledge in relation to this cultivation, the critical points of more impact on this value chain in Mexico that we have detected, with negative repercussions for the economy of fruit farmers, are located in stages: production (flowering and anthracnosis) and industrialization (use of vegetable residuals generated in fresh mango process of industrialization). This revision presents a global analysis of stages that put in risk to this value chain in Mexico, as well as the causes and possible solutions to these, by means of alternati...
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Research Interests: Botany, Plant Biology, Biology, Medicine, Mutation, and 15 moreAnimals, Bacteria, Cluster Analysis, Hemiptera, PEST, Bacillus subtilis, Inoculation, Bemisia tabaci, Host Pathogen Interactions, Hypersensitive Response, Induced Systemic Resistance, PLANT PROTEINS, Planta, Lycopersicon esculentum, and Jasmonic Acid
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Raw data for metabolic fingerprinting of tomato roots by DLI-ESI-MS to examine the effect of mycorrhizal colonization on the global metabolic profile of WT and <em>spr2</em> mutant plants. Data were acquired in positive mode... more
Raw data for metabolic fingerprinting of tomato roots by DLI-ESI-MS to examine the effect of mycorrhizal colonization on the global metabolic profile of WT and <em>spr2</em> mutant plants. Data were acquired in positive mode by direct liquid introduction electrospray ionization (DLI-MS).
Ever since the seminal discovery of systemic wound signaling in tomato and potato plants by Green and Ryan (Science 1972), a number of candidate systemic wound signals have been proposed. These can be classified into three groups: (1)... more
Ever since the seminal discovery of systemic wound signaling in tomato and potato plants by Green and Ryan (Science 1972), a number of candidate systemic wound signals have been proposed. These can be classified into three groups: (1) Chemical signals, including the alarm hormone systemin and other peptide hormones, jasmonic acid is a phytohormone, as well as reactive oxygen species (ROS); (2) physical signals, including electrical and hydraulic signals; and (3) herbivore-induced volatile compounds, including green leafy volatiles and terpenes. These signals are generated at or close to the site of herbivore-inflicted injury and systemically move to target tissues where they induce defense responses. Chemical and physical signals depend on the connectivity of the plant body, whereas volatile compounds are released into the airspace. Different plants with different morphologies and ecological niches employ different modes of systemic signaling.
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Heat stress is poised to become a major factor negatively affecting plant performance worldwide. In terms of world food security, increased ambient temperatures are poised to reduce yields in cereals and other economically important... more
Heat stress is poised to become a major factor negatively affecting plant performance worldwide. In terms of world food security, increased ambient temperatures are poised to reduce yields in cereals and other economically important crops. Grain amaranths are known to be productive under poor and/or unfavorable growing conditions that significantly affect cereals and other crops. Several physiological and biochemical attributes have been recognized to contribute to this favorable property, including a high water-use efficiency and the activation of a carbon starvation response. This study reports the behavior of the three grain amaranth species to two different stress conditions: short-term exposure to heat shock (HS) conditions using young plants kept in a conditioned growth chamber or long-term cultivation under severe heat stress in greenhouse conditions. The latter involved exposing grain amaranth plants to daylight temperatures that hovered around 50°C, or above, for at least 4...
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El cempasúchil (Tagetes erecta) es una planta asterácea comúnmente utilizada como flor ornamental y ceremonial durante la temporada de otoño en México. Las plantas de cempasúchil cultivadas en el campo presentaron síntomas de la... more
El cempasúchil (Tagetes erecta) es una planta asterácea comúnmente utilizada como flor ornamental y ceremonial durante la temporada de otoño en México. Las plantas de cempasúchil cultivadas en el campo presentaron síntomas de la enfermedad de la mancha foliar bacteriana. Se aisló una cepa bacteriana que potencialmente causa la enfermedad de las manchas. El objetivo principal de esta investigación fue clasificar esta bacteria y evaluar su patogenicidad en cempasúchil y otras especies vegetales. El perfil bioquímico identificó esta cepa como Pseudomonas syringae LF2012. El análisis filogenético del gen ARNr 16S reveló una estrecha relación con genomoespecies de Pseudomonas. El perfil de macrorestricción I-CeuI del cromosoma confirmó su alto grado de similitud con distintos patovares de P. syringae. P. syringae LF2012 causa la enfermedad de las manchas cuando se inocula por aspersión en hojas de cempasúchil. Los ensayos de infección de plantas de otras familias (Asteraceae, Brassicacea...
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Systemin (s) and jasmonic acid (JA) play a central role in the damage response in tomato ( Solanum lycopersicum ). JA is also known to regulate the arbuscular mycorrhizal (AM) symbiosis in this and other plant species. An experiment was... more
Systemin (s) and jasmonic acid (JA) play a central role in the damage response in tomato ( Solanum lycopersicum ). JA is also known to regulate the arbuscular mycorrhizal (AM) symbiosis in this and other plant species. An experiment was made in which the possible participation of the systemin in early stages of the establishment of the mycorrhiza was evaluated. Exogenous systemin appliction to a very rapid and transient increase of root glucanase and quitinase activity patterns at 3, 6 and 12 days after emergence (dae). Arbuscular mycorrhizal fungi (AMF) species produced a gradual increment leading to transient peaks of activity, at 3 and 6 dae (for chitinase) and 9 dae (for β-1,3-glucanase). The pattern suggests the establishment of a pre-symbiotic dialogue plant - AMF which appeared to be partly modulated by systemin, judging by the synergic effect on β-1,3-glucanase activity observed in the systemin and AMF treatment. A similarly positive effect on β-1,3-glucanase activity was ob...
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While most plants die below a threshold of water content, desiccation-tolerant species display specific responses that allow them to survive extreme dehydration. Some of these responses are activated at critical stages during water loss... more
While most plants die below a threshold of water content, desiccation-tolerant species display specific responses that allow them to survive extreme dehydration. Some of these responses are activated at critical stages during water loss and could represent the difference between desiccation tolerance (DT) and death. Here, we report the development of a simple and reproducible system to determine DT in Selaginella species. The system is based on exposure of excised tissue to a dehydration agent inside small containers, and subsequent evaluation for tissue viability. We evaluated several methodologies to determine viability upon desiccation including: triphenyltetrazolium chloride (TTC) staining, the quantum efficiency of photosystem II, antioxidant potential and relative electrolyte leakage. Our results show that the TTC test is a simple and accurate assay to identify novel desiccation-tolerant Selaginella species, and can also indicate viability in other desiccation-tolerant models ...
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Transcriptomic analysis of grain amaranth (Amaranthus hypochondriacus) using 454 pyrosequencing: comparison with A. tuberculatus, expression profiling in stems and in response to biotic and abiotic stress
The data were obtained from wild-type tomato plants (roots or leaves) and spr2 mutants, with different degrees of mycorrhization.<br> Amplifications were performed using SYBR Green detection chemistry and run in triplicate in... more
The data were obtained from wild-type tomato plants (roots or leaves) and spr2 mutants, with different degrees of mycorrhization.<br> Amplifications were performed using SYBR Green detection chemistry and run in triplicate in 96-well reaction plates with the CFX96 Touch Real-Time PCR Detection System (Bio-Rad, Hercules, CA, USA). The data was analyzed by the delta delta ct method.
The functional characterization of an Amaranthus hypochondriacus Natterin-4-Like-1 gene (AhN4L-1) coding for an unknown function protein characterized by the presence of an aerolysin-like pore-forming domain in addition to two... more
The functional characterization of an Amaranthus hypochondriacus Natterin-4-Like-1 gene (AhN4L-1) coding for an unknown function protein characterized by the presence of an aerolysin-like pore-forming domain in addition to two amaranthin-like agglutinin domains is herewith described. Natterin and nattering-like proteins have been amply described in the animal kingdom. However, the role of nattering-like proteins in plants is practically unknown. The results described in this study, obtained from gene expression data in grain amaranth and from AhN4L-1-overexpressing Arabidopsis thaliana plants indicated that this gene was strongly induced by several biotic and abiotic conditions in grain amaranth, whereas data obtained from the overexpressing Arabidopsis plants further supported the defensive function of this gene, mostly against bacterial and fungal plant pathogens. GUS and GFP AhN4L-1 localization in roots tips, leaf stomata, stamens and pistils also suggested a defensive function ...
Defoliation tolerance (DT) in Amaranthus cruentus is known to reach its apex at the panicle emergence (PE) phase and to decline to minimal levels at flowering (FL). In this study, defoliation-induced changes were recorded in the content... more
Defoliation tolerance (DT) in Amaranthus cruentus is known to reach its apex at the panicle emergence (PE) phase and to decline to minimal levels at flowering (FL). In this study, defoliation-induced changes were recorded in the content of non-structural carbohydrates and raffinose family oligosaccharides (RFOs), and in the expression and/or activity of sugar starvation response-associated genes in plants defoliated at different vegetative and reproductive stages. This strategy identified sugar-starvation-related factors that explained the opposite DT observed at these key developmental stages. Peak DT at PE was associated with increased cytosolic invertase (CI) activity in all organs and with the extensive induction of various class II trehalose-phosphate synthase (TPS) genes. Contrariwise, least DT at FL coincided with a sharp depletion of starch reserves and with sucrose (Suc) accumulation, in leaves and stems, the latter of which was consistent with very low levels of CI and vac...
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Taxonomically restricted genes, or TRGs, are specific to a particular taxon that can be found only in the genomes of single species or are represented as orthologs in closely related genera. Despite being regarded with a mixture of... more
Taxonomically restricted genes, or TRGs, are specific to a particular taxon that can be found only in the genomes of single species or are represented as orthologs in closely related genera. Despite being regarded with a mixture of skepticism and awe by the scientific community, progress has been gradually attained in the understanding of their presumed origin and function in most, if not all, forms of life. Grain amaranth is not an exception, as shown by the numerous unknown function TRGs that were unveiled by a recent transcriptomic analysis undergone under different (a)biotic stress conditions. True to their nature, amaranth TRGs appear to be mostly stress-related genes that may offer a clue to better understand the ability of these remarkable plants to thrive under unfavorable ambient conditions. This chapter will concentrate on the description of what has gradually emerged from the incipient study of TRGs in grain amaranth and will place this knowledge in the context of what is known about these enigmatic genes in other organisms.
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Arbuscular mycorrhizal fungi (AMF) colonization, sampled at 32–50 days post-inoculation (dpi), was significantly reduced in suppressor of prosystemin-mediated responses2 (spr2) mutant tomato plants impaired in the ω−3 FATTY ACID... more
Arbuscular mycorrhizal fungi (AMF) colonization, sampled at 32–50 days post-inoculation (dpi), was significantly reduced in suppressor of prosystemin-mediated responses2 (spr2) mutant tomato plants impaired in the ω−3 FATTY ACID DESATURASE7 (FAD7) gene that limits the generation of linolenic acid and, consequently, the wound-responsive jasmonic acid (JA) burst. Contrary to wild-type (WT) plants, JA levels in root and leaves of spr2 mutants remained unchanged in response to AMF colonization, further supporting its regulatory role in the AM symbiosis. Decreased AMF colonization in spr2 plants was also linked to alterations associated with a disrupted FAD7 function, such as enhanced salicylic acid (SA) levels and SA-related defense gene expression and a reduction in fatty acid content in both mycorrhizal spr2 roots and leaves. Transcriptomic data revealed that lower mycorrhizal colonization efficiency in spr2 mutants coincided with the modified expression of key genes controlling gibbe...
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Systemin is a peptide hormone that regulates the wound response in tomato plants. Consequently, the overexpression of its prosystemin (ProSys) precursor protein leads to a resource-demanding constitutive activation of tomato’s... more
Systemin is a peptide hormone that regulates the wound response in tomato plants. Consequently, the overexpression of its prosystemin (ProSys) precursor protein leads to a resource-demanding constitutive activation of tomato’s wound-response. According to the growth vs. defense resource allocation premise, ProSys overexpression should negatively affect the physiological fitness of tomato plants. The present study was performed to explore why the opposite effect was steadily observed, instead. It was based on the premise that a better understanding of this unexpected outcome could help establish improved wound and related defense responses without negatively affecting crop productivity. To this effect, an experimental strategy was deployed to measure various physiological, biochemical and molecular parameters associated with either development, productivity, defense or in combination in untransformed (WT) and ProSys overexpressing (ProSys-OE) tomato plants. Thus, the chlorophyll fluo...
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A cDNA, encoding a cysteine protease inhibitor (AhCPI), was isolated from an immature seed cDNA library of grain amaranth (Amaranthus hypochondriacus L.) and characterized. It encoded a polypeptide of 247 amino acids (aa), including a... more
A cDNA, encoding a cysteine protease inhibitor (AhCPI), was isolated from an immature seed cDNA library of grain amaranth (Amaranthus hypochondriacus L.) and characterized. It encoded a polypeptide of 247 amino acids (aa), including a putative N-terminal signal peptide. Other relevant regions found in its sequence included the G and PW conserved aa motifs, the consensus LARFAV sequence for phytocystatins and the reactive site QVVAG. The predicted aa sequence for AhCPI showed a significant homology to other plant cystatins. Gene expression analyses indicated that AhCPI was constitutively expressed in mature seeds, and gradually decreased during germination. In vegetative tissues, AhCPI was expressed in the radicle and hypocotyls of seedlings and in the stems and roots of young plantlets. Its expression in roots and stems increased substantially in response to water deficit, salinity-, cold- and heat-stress, whereas heat-stress induced a rapid and transient accumulation of AhCPI transcripts in leaves. The results obtained were suggestive of multiple roles for AhCPI in grain amaranth, acting as a regulator of seed germination and as a protective agent against diverse types of abiotic stress, which induced this gene in a tissue- and stress-specific manner. The work herewith described reports a novel, and apparently, single cystatin protein in which, in agreement with other plant model systems, could have a regulatory role in germination, and further expands previous findings linking the accumulation of protease inhibitors, mostly of the serine proteinase type, with protection against (a)biotic stress in A. hypochondriacus.
Research Interests: Plant Biology, Seed germination, Abiotic Stress, Gene expression, Plant Physiology, and 15 morePlant Roots, Plant Physiology and Biochemistry, Molecular cloning, Germination, Amaranthus, Heat stress, Model System, Amino Acid Profile, Amino Acid Sequence, Base Sequence, PLANT PROTEINS, cDNA library, Cysteine Proteinase Inhibitors, Molecular Sequence Data, and Cysteine Protease
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Research Interests: Engineering, Physics, Chemistry, Photosynthesis, Biology, and 15 moreMedicine, Multidisciplinary, Phosphorus, Nitrogen, Plant Roots, PLoS one, Amino Acids, Amaranthus, Seeds, Burkholderia, Carbohydrate metabolism, Gene Expression Regulation, Gene expression profiling, Plant Leaves, and real time polymerase chain reaction
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... Proteinase inhibitors have also been implicated in the regulation of programmed cell death events required for normal development and differentiation (Fukuda 1997, Solomon et al. ... The abiotic stress experiments were performed... more
... Proteinase inhibitors have also been implicated in the regulation of programmed cell death events required for normal development and differentiation (Fukuda 1997, Solomon et al. ... The abiotic stress experiments were performed according to Chao et al. (1999). ...
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A study was performed to determine the effect of the systemin polypeptide on the bio-protective effect of arbuscular mycorrhizal fungi (AMF) in tomato plants infected with Alternaria solani, Phytophthora infestans or P. parasitica. Before... more
A study was performed to determine the effect of the systemin polypeptide on the bio-protective effect of arbuscular mycorrhizal fungi (AMF) in tomato plants infected with Alternaria solani, Phytophthora infestans or P. parasitica. Before infection, tomato plants were colonized with two different AMF, Glomus fasciculatum or G. clarum. In addition, a group of inoculated plants was treated with systemin, just after emergence. The exogenous application of systemin marginally suppressed the resistance against A. solani leaf blight observed in G. fasciculatum mycorrhizal plants but significantly enhanced it in plants colonized with G. clarum. Systemin induced resistance to P. parasitica in leaves of G. fasciculatum mycorrhizal plants, in which AMF colonization alone was shown to have no protective effect. Conversely, none of the treatments led to resistance to root or stem rots caused by P. infestans or P. parasitica. The above effects did not correlate with changes in the activity levels of beta-1,3-glucanase (BG), chitinase (CHI), peroxidase (PRX), and phenylalanine ammonium lyase (PAL) in leaves of infected plants. However, they corroborated previous reports showing that colonization by AMF can lead to a systemic resistance response against A. solani. Systemic resistance to A. solani was similarly observed in non-mycorrhizal systemin-treated plants, which, in contrast, showed increased susceptibility to P. infestans and P. parasitica. The results indicated that the pattern of systemic disease resistance conferred by mycorrhizal colonization was dependent on the AMF employed and could be altered by the exogenous application of systemin, by means of a still undefined mechanism.