scholarly journals Contribution of Structural Chromosome Mutants to the Study of Meiosis in Plants

2015 ◽  
Vol 147 (1) ◽  
pp. 55-69 ◽  
Author(s):  
Tomás Naranjo
Keyword(s):  
Arabidopsis Thaliana ◽  
Gene Silencing ◽  
Plant Species ◽  
Chromosome Segregation ◽  
Molecular Mechanisms ◽  
Meiotic Process ◽  
Meiotic Mutants ◽  
Chromosome Domains ◽  
Structural Chromosome ◽  
Complex Events

Dissection of the molecular mechanisms underlying the transition through the complex events of the meiotic process requires the use of gene mutants or RNAi-mediated gene silencing. A considerable number of meiotic mutants have been isolated in plant species such as Arabidopsis thaliana, maize or rice. However, structural chromosome mutants are also important for the identification of the role developed by different chromosome domains in the meiotic process. This review summarizes the contribution of studies carried out in plants using structural chromosome variations. Meiotic events concerning the search of the homologous partner, the control of number and distribution of chiasmata, the mechanism of pairing correction, and chromosome segregation are considered.

Activity and Phylogenetics of the Broadly Occurring Family of Microbial Nep1-Like Proteins

2019 ◽  
Vol 57 (1) ◽  
pp. 367-386 ◽  
Author(s):  
Michael F. Seidl ◽  
Guido Van den Ackerveken
Keyword(s):  
Arabidopsis Thaliana ◽  
Plant Species ◽  
Historical Perspective ◽  
Plasma Membranes ◽  
Molecular Mechanisms ◽  
Plant Immunity ◽  
Taxonomic Distribution ◽  
Outer Leaflet ◽  
Molecular Patterns ◽  
Shed Light

Necrosis- and ethylene-inducing peptide 1 (Nep1)-like proteins (NLP) have an extremely broad taxonomic distribution; they occur in bacteria, fungi, and oomycetes. NLPs come in two forms, those that are cytotoxic to eudicot plants and those that are noncytotoxic. Cytotoxic NLPs bind to glycosyl inositol phosphoryl ceramide (GIPC) sphingolipids that are abundant in the outer leaflet of plant plasma membranes. Binding allows the NLP to become cytolytic in eudicots but not monocots. The function of noncytotoxic NLPs remains enigmatic, but the expansion of NLP genes in oomycete genomes suggests they are important. Several plant species have evolved the capacity to recognize NLPs as molecular patterns and trigger plant immunity, e.g., Arabidopsis thaliana detects nlp peptides via the receptor-like protein RLP23. In this review, we provide a historical perspective from discovery to understanding of molecular mechanisms and describe the latest developments in the NLP field to shed light on these fascinating microbial proteins.

scholarly journals Arabidopsis thaliana interaction with Ensifer meliloti can support plant growth under N-deficiency

2020 ◽  
Author(s):  
Grace Armijo ◽  
Tatiana Kraiser ◽  
María P. Medina ◽  
Diana E. Gras ◽  
Ana Zúñiga ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Life Cycle ◽  
Plant Growth ◽  
Plant Species ◽  
Molecular Mechanisms ◽  
Growth Promotion ◽  
N Fixation ◽  
N Nutrition ◽  
Ensifer Meliloti ◽  
N Deficiency

ABSTRACTNitrogen (N) is an essential macronutrient for plants. Some plant species obtain this nutrient by interacting with N-fixing bacteria. These beneficial interactions are well described in legumes but have also been observed in non-legume plant species that are unable to form root nodules. We studied the expanding role of beneficial plant-bacteria interactions for N-nutrition in the widely used model plant Arabidopsis thaliana. We found that the bacteria Ensifer meliloti enhanced A. thaliana growth under severe N-deficiency conditions, allowing plants to complete their life cycle. Our results showed that bacteria colonize the rhizosphere associated with the epidermis of the plant root. We also demonstrated that A. thaliana possesses genes that are critical for this beneficial interaction and are required for plant-growth promotion by E. meliloti under N-deficiency.This work shows association between A. thaliana and E. meliloti for plant nutrition under severe N-deficiency, and suggests that plants have conserved-molecular mechanisms to interact with N-fixing bacteria to procure N and escape adverse conditions. Under these circumstances, the supply of N via N-fixation is critical for survival, allowing the plant to complete its life cycle. Our findings provide a new framework and an experimental model system that expand our understanding of plant-rhizobia interactions for plant N-nutrition.

scholarly journals Suppression of eNOS-derived superoxide by caveolin-1: a biopterin-dependent mechanism

2011 ◽  
Vol 301 (3) ◽  
pp. H903-H911 ◽  
Author(s):  
Kanchana Karuppiah ◽  
Lawrence J. Druhan ◽  
Chun-an Chen ◽  
Travis Smith ◽  
Jay L. Zweier ◽  
...  
Keyword(s):  
Gene Silencing ◽  
Oxidase Activity ◽  
Molecular Mechanisms ◽  
Critical Role ◽  
Caveolin 1 ◽  
Calcium Calmodulin Dependent ◽  
Enos Uncoupling ◽  
Nadph Oxidation ◽  
Interfering Rna

In the vasculature, nitric oxide (NO) is generated by endothelial NO synthase (eNOS) in a calcium/calmodulin-dependent reaction. In the absence of the requisite eNOS cofactor tetrahydrobiopterin (BH4), NADPH oxidation is uncoupled from NO generation, leading to the production of superoxide. Although this phenomenon is apparent with purified enzyme, cellular studies suggest that formation of the BH4 oxidation product, dihydrobiopterin, is the molecular trigger for eNOS uncoupling rather than BH4 depletion alone. In the current study, we investigated the effects of both BH4 depletion and oxidation on eNOS-derived superoxide production in endothelial cells in an attempt to elucidate the molecular mechanisms regulating eNOS oxidase activity. Results demonstrated that pharmacological depletion of endothelial BH4 does not result in eNOS oxidase activity, whereas BH4 oxidation gave rise to significant eNOS-oxidase activity. These findings suggest that the endothelium possesses regulatory mechanisms, which prevent eNOS oxidase activity from pterin-free eNOS. Using a combination of gene silencing and pharmacological approaches, we demonstrate that eNOS-caveolin-1 association is increased under conditions of reduced pterin bioavailability and that this sequestration serves to suppress eNOS uncoupling. Using small interfering RNA approaches, we demonstrate that caveolin-1 gene silencing increases eNOS oxidase activity to 85% of that observed under conditions of BH4 oxidation. Moreover, when caveolin-1 silencing was combined with a pharmacological inhibitor of AKT, BH4 depletion increased eNOS-derived superoxide to 165% of that observed with BH4 oxidation. This study identifies a critical role of caveolin-1 in the regulation of eNOS uncoupling and provides new insight into the mechanisms through which disease-associated changes in caveolin-1 expression may contribute to endothelial dysfunction.

scholarly journals Overexpression of SgGH3.1 from Fine-Stem Stylo (Stylosanthes guianensis var. intermedia) Enhances Chilling and Cold Tolerance in Arabidopsis thaliana

Genes ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1367
Author(s):  
Ming Jiang ◽  
Long-Long Ma ◽  
Huai-An Huang ◽  
Shan-Wen Ke ◽  
Chun-Sheng Gui ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Cold Stress ◽  
Stress Responses ◽  
Molecular Mechanisms ◽  
Transcriptome Profiling ◽  
Pasture Legumes ◽  
Cold Tolerant ◽  
Whole Transcriptome ◽  
Altered Sensitivity ◽  
Exogenous Iaa

Stylosanthes (stylo) species are commercially significant tropical and subtropical forage and pasture legumes that are vulnerable to chilling and frost. However, little is known about the molecular mechanisms behind stylos’ responses to low temperature stress. Gretchen-Hagen 3 (GH3) proteins have been extensively investigated in many plant species for their roles in auxin homeostasis and abiotic stress responses, but none have been reported in stylos. SgGH3.1, a cold-responsive gene identified in a whole transcriptome profiling study of fine-stem stylo (S. guianensis var. intermedia) was further investigated for its involvement in cold stress tolerance. SgGH3.1 shared a high percentage of identity with 14 leguminous GH3 proteins, ranging from 79% to 93%. Phylogenetic analysis classified SgGH3.1 into Group Ⅱ of GH3 family, which have been proven to involve with auxins conjugation. Expression profiling revealed that SgGH3.1 responded rapidly to cold stress in stylo leaves. Overexpression of SgGH3.1 in Arabidopsis thaliana altered sensitivity to exogenous IAA, up-regulated transcription of AtCBF1-3 genes, activated physiological responses against cold stress, and enhanced chilling and cold tolerances. This is the first report of a GH3 gene in stylos, which not only validated its function in IAA homeostasis and cold responses, but also gave insight into breeding of cold-tolerant stylos.

scholarly journals FRA1 modulates cortical microtubule localization of CMU proteins

2019 ◽  
Author(s):  
Anindya Ganguly ◽  
Chuanmei Zhu ◽  
Weizu Chen ◽  
Ram Dixit
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Wall ◽  
Molecular Mechanisms ◽  
Cortical Microtubule ◽  
Cellulose Synthase ◽  
Lateral Stability ◽  
Cortical Microtubules ◽  
Tail Region ◽  
Opposing Effect ◽  
Growth And Reproduction

ABSTRACTConstruction of the cell wall demands harmonized deposition of cellulose and matrix polysaccharides. Cortical microtubules orient the deposition of cellulose by guiding the trajectory of plasma membrane-embedded cellulose synthase complexes. Vesicles containing matrix polysaccharides are thought to be transported by the FRA1 kinesin to facilitate their secretion along cortical microtubules. The cortical microtubule cytoskeleton thus provides a platform to coordinate the delivery of cellulose and matrix polysaccharides, but the underlying molecular mechanisms remain unknown. Here, we show that the tail region of the FRA1 kinesin physically interacts with CMU proteins which are important for the microtubule-dependent guidance of cellulose synthase complexes. Interaction with CMUs did not affect microtubule binding or motility of the FRA1 kinesin but had an opposing effect on the cortical microtubule localization of CMU1 and CMU2 proteins, thus regulating the lateral stability of cortical microtubules. Phosphorylation of the FRA1 tail region by CKL6 inhibited binding to CMUs and consequently reversed the extent of cortical microtubule decoration by CMU1 and CMU2. Genetic experiments demonstrated the significance of this interaction to the growth and reproduction of Arabidopsis thaliana plants. We propose that modulation of CMU’s microtubule localization by FRA1 provides a mechanism to control the coordinated deposition of cellulose and matrix polysaccharides.

Evaluation of virus-induced gene silencing methods for forage legumes including alfalfa, sainfoin, and fenugreek

2019 ◽  
Vol 99 (6) ◽  
pp. 917-926 ◽  
Author(s):  
Champa Wijekoon ◽  
Stacy D. Singer ◽  
Randall J. Weselake ◽  
Udaya Subedi ◽  
Surya N. Acharya
Keyword(s):  
Gene Silencing ◽  
Plant Species ◽  
Reverse Genetics ◽  
Functional Characterization ◽  
Homologous Gene ◽  
Virus Induced Gene Silencing ◽  
Forage Legumes ◽  
Crop Species ◽  
Barrel Medic ◽  
Trigonella Foenum Graecum L

Virus-induced gene silencing (VIGS) is a rapid reverse genetics tool that has been developed in a wide variety of plant species for assessing gene functions. However, while VIGS has been utilized successfully in the diploid model leguminous species Medicago truncatula (Gaertn.) (barrel medic), such a platform has yet to be established in forage legume crop species. Therefore, we evaluated the effectiveness of this method in forage legumes using a previously developed PEBV (pea early browning virus) system whereby a fragment of the pea (Pisum sativum L.) PHYTOENE DESATURASE (PDS) gene was transferred into a range of alfalfa (Medicago sativa L.), sainfoin (Onobrychis viciifolia Scop.), and fenugreek (Trigonella foenum-graecum L.) cultivars using leaf infiltration and apical meristem injection. Barrel medic was used as a positive control. Gene silencing was observed after 10–15 d through the presence of a leaf bleaching phenotype, and was confirmed using quantitative real-time RT-PCR. Silencing of PDS was achieved in a selection of cultivars in all species assessed, with the highest silencing efficiency apparent in fenugreek. The introduction of a highly homologous gene fragment from a heterologous plant species to target endogenous genes for transient VIGS-based silencing in a range of species of interest represents a potentially useful strategy for the rapid functional characterization of candidate genes in forages.

scholarly journals Structural and functional studies of Arabidopsis thaliana legumain beta reveal isoform specific mechanisms of activation and substrate recognition

2020 ◽  
Vol 295 (37) ◽  
pp. 13047-13064 ◽  
Author(s):  
Elfriede Dall ◽  
Florian B. Zauner ◽  
Wai Tuck Soh ◽  
Fatih Demir ◽  
Sven O. Dahms ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Arabidopsis Thaliana ◽  
Cyclic Peptides ◽  
Molecular Mechanisms ◽  
Functional Studies ◽  
Plant Characteristic ◽  
Activation Mechanisms ◽  
Binding Pockets ◽  
First Time ◽  
Autocatalytic Activation

The vacuolar cysteine protease legumain plays important functions in seed maturation and plant programmed cell death. Because of their dual protease and ligase activity, plant legumains have become of particular biotechnological interest, e.g. for the synthesis of cyclic peptides for drug design or for protein engineering. However, the molecular mechanisms behind their dual protease and ligase activities are still poorly understood, limiting their applications. Here, we present the crystal structure of Arabidopsis thaliana legumain isoform β (AtLEGβ) in its zymogen state. Combining structural and biochemical experiments, we show for the first time that plant legumains encode distinct, isoform-specific activation mechanisms. Whereas the autocatalytic activation of isoform γ (AtLEGγ) is controlled by the latency-conferring dimer state, the activation of the monomeric AtLEGβ is concentration independent. Additionally, in AtLEGβ the plant-characteristic two-chain intermediate state is stabilized by hydrophobic rather than ionic interactions, as in AtLEGγ, resulting in significantly different pH stability profiles. The crystal structure of AtLEGβ revealed unrestricted nonprime substrate binding pockets, consistent with the broad substrate specificity, as determined by degradomic assays. Further to its protease activity, we show that AtLEGβ exhibits a true peptide ligase activity. Whereas cleavage-dependent transpeptidase activity has been reported for other plant legumains, AtLEGβ is the first example of a plant legumain capable of linking free termini. The discovery of these isoform-specific differences will allow us to identify and rationally design efficient ligases with application in biotechnology and drug development.

scholarly journals Genetic and molecular basis of floral induction in Arabidopsis thaliana

2020 ◽  
Vol 71 (9) ◽  
pp. 2490-2504 ◽  
Author(s):  
Atsuko Kinoshita ◽  
René Richter
Keyword(s):  
Arabidopsis Thaliana ◽  
Reproductive Success ◽  
Environmental Conditions ◽  
Molecular Basis ◽  
Recent Progress ◽  
Molecular Mechanisms ◽  
Floral Induction ◽  
Life Cycles ◽  
Complex Processes ◽  
Technological Advances

Abstract Many plants synchronize their life cycles in response to changing seasons and initiate flowering under favourable environmental conditions to ensure reproductive success. To confer a robust seasonal response, plants use diverse genetic programmes that integrate environmental and endogenous cues and converge on central floral regulatory hubs. Technological advances have allowed us to understand these complex processes more completely. Here, we review recent progress in our understanding of genetic and molecular mechanisms that control flowering in Arabidopsis thaliana.

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