Plant defense
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Rescooped by Renato Dantas from Plant-Microbe Symbiosis
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Drought stress provokes the down-regulation of methionine and ethylene biosynthesis pathways in Medicago truncatula roots and nodules

Symbiotic nitrogen fixation is one of the first physiological processes inhibited in legume plants under water-deficit conditions. Despite the progress made in the last decades, the molecular mechanisms behind this regulation are not fully understood yet. Recent proteomic work carried out in the model legume Medicago truncatula provided the first indications of a possible involvement of nodule methionine (Met) biosynthesis and related pathways in response to water deficit conditions. To better understand this involvement, the drought-induced changes in expression and content of enzymes involved in the biosynthesis of Met, S-adenosyl-L-methionine (SAM) and ethylene in M. truncatula root and nodules were analyzed using targeted approaches. Nitrogen-fixing plants were subjected to a progressive water deficit and a subsequent recovery period. Besides the physiological characterization of the plants, the content of total sulfur, sulfate and main S-containing metabolites was measured. Results presented here show that S availability is not a limiting factor in the drought-induced decline of nitrogen fixation rates in M. truncatula plants and provide evidences for a down-regulation of the Met and ethylene biosynthesis pathways in roots and nodules in response to water deficit conditions.


Via Jean-Michel Ané
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Rescooped by Renato Dantas from Plant Stress
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Phototropism Growing towards an Understanding of Plant Movement

Phototropism Growing towards an Understanding of Plant Movement | Plant defense | Scoop.it

Via Mary Williams, R K Upadhyay
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Posttranslationally Modified Small-Peptide Signals in Plants

Posttranslationally Modified Small-Peptide Signals in Plants | Plant defense | Scoop.it

Cell-to-cell signaling is essential for many processes in plant growth and development, including coordination of cellular responses to developmental and environmental cues. Cumulative studies have demonstrated that peptide signaling plays a greater-than-anticipated role in such intercellular communication. Some peptides act as signals during plant growth and development, whereas others are involved in defense responses or symbiosis. Peptides secreted as signals often undergo posttranslational modification and proteolytic processing to generate smaller peptides composed of approximately 10 amino acid residues. Such posttranslationally modified small-peptide signals constitute one of the largest groups of secreted peptide signals in plants. The location of the modification group incorporated into the peptides by specific modification enzymes and the peptide chain length defined by the processing enzymes are critical for biological function and receptor interaction. This review covers 20 years of research into posttranslationally modified small-peptide signals in plants.

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Rescooped by Renato Dantas from Plant Biology Teaching Resources (Higher Education)
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Molecular Plant (2012): The Long-Sought-After Salicylic Acid Receptors

Molecular Plant (2012): The Long-Sought-After Salicylic Acid Receptors | Plant defense | Scoop.it

The plant hormone salicylic acid (SA) plays a prominent role in modulating plant immune responses against diverse pathogens. SA also influences other physiological processes in plants, such as senescence-associated gene expression, basal thermogenesis, and seed germination (Vlot et al., 2009). Because of the critical role of SA in regulating plant immunity, growth, and development, there has been immense research about SA, which has resulted in the discovery of numerous plant genes involved in SA biosynthesis or signal transduction. One of the most notable findings was the identification of NPR1 (non-expressor of pathogenesis protein 1) (Cao et al., 1994; Delaney et al., 1995), a gene that encodes a master regulatory protein of SA-dependent defense responses and is a transcriptional co-activator of the TGA clade of bZIP transcription factors (transcription factors that contain basic region/leucine zipper motif)...

 

Elham Attarana and Sheng Yang He


Via Nicolas Denancé, Mary Williams
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One-Step Synthesis of Betalains Using a Novel Betalamic Acid Derivatized Support

One-Step Synthesis of Betalains Using a Novel Betalamic Acid Derivatized Support | Plant defense | Scoop.it

Betalains are plant pigments with high antioxidant and cancer chemopreventive properties used by the food industry as safe colorants. Betalains are restricted to species of the order Caryophyllales and difficulty in obtaining individual molecules has limited their structural identification and application. This study was designed to develop a betalamic acid-derivatized support generated from a primary amine polymer. The novel material presents color properties of a pseudo-betaxanthin and it is stable for at least six months. The bond formed can be displaced at mild conditions by the addition of amines in aqueous solutions over a broad pH range and at 25 ºC. This releases the betalamic acid while forming the corresponding pigment. This one-step procedure significantly simplifies the process of obtaining semi-synthetic betalains and it is optimized here for the formation of betaxanthins and betacyanins derived from tyramine, dopamine, pyrrolidine and indoline. The new method makes access to single betalains available to the entire scientific community and could stimulate research and applications in the field.

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Rescooped by Renato Dantas from Plant Stress
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The Brassinosteroid Signaling Pathway - New Key Players and Interconnections with Other Signaling Networks Crucial for Plant Development and Stress Tolerance

The Brassinosteroid Signaling Pathway - New Key Players and Interconnections with Other Signaling Networks Crucial for Plant Development and Stress Tolerance | Plant defense | Scoop.it

Recent studies clearly indicated that some of the components of BR signaling pathway act as multifunctional proteins involved in other signaling networks regulating diverse physiological processes, such as photomorphogenesis, cell death control, stomatal development, flowering, plant immunity to pathogens and metabolic responses to stress conditions, including salinity. Regulation of some of these processes is mediated through a crosstalk between BR signalosome and the signaling cascades of other hormones, including auxin, abscisic acid, ethylene and salicylic acid. Unravelling the complicated mechanisms of BR signaling and its interconnections with other molecular networks may be of great importance for future practical applications in agriculture.


Via Elsa Ballini, R K Upadhyay
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Jasmonate signaling and crosstalk with gibberellin and ethylene

Jasmonate signaling and crosstalk with gibberellin and ethylene | Plant defense | Scoop.it

The phytohormone jasmonate (JA) plays essential roles in plant growth, development and defense. In response to the JA signal, the CORONATINE INSENSITIVE 1 (COI1)-based SCF complexes recruit JASMONATE ZIM-domain (JAZ) repressors for ubiquitination and degradation, and subsequently regulate their downstream signaling components essential for various JA responses. Tremendous progress has been made in understanding the JA signaling pathway and its crosstalk with other phytohormone pathways during the past two decades. Recent studies have revealed that a variety of positive and negative regulators act as targets of JAZs to control distinctive JA responses, and that JAZs and these regulators function as crucial interfaces to mediate synergy and antagonism between JA and other phytohormones. Owing to different regulatory players in JA perception and JA signaling, a fine-tuning of JA-dependent processes in plant growth, development and defense is achieved. In this review, we will summarize the latest progresses in JA signaling and its crosstalk with gibberellin and ethylene.

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Understanding Plant Disease Resistance

Prof. Lee Hadwiger of Washington State University's Department of Plant Pathology describes how pea plants resist bean diseases. Hadwiger and his colleagues ...
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