Plant Signaling & Behavior最新文献

Arabidopsis DYNAMIN-RELATED PROTEIN1A (AtDRP1A) and AtDRP2B are large GTPases that function together in endocytosis for effective cytokinesis, cell enlargement and development. A recent study shows that these DRPs contribute to ligand-induced endocytosis of the immune receptor FLAGELLIN SENSING2 (AtFLS2) to modulate flg22-immune signaling, and they are required for immunity against Pseudomonas syringae pv. tomato bacteria. Here, we demonstrate that atdrp1a and atdrp2b single mutants showed increased susceptibility to Botrytis cinerea indicating that AtDRP1A and AtDRP2B are necessary for effective resistance against this necrotrophic fungus. Thus, we expanded our limited understanding of clathrin endocytic accessory proteins in immunity against plant pathogens.

Tomato (Solanum lycopersicum L.) is an important crop that possesses about 35,000 genes. The treatment of plants with elicitors or pathogen attacks causes a cascade of defense reactions. We investigated tomato responses to the BamFX^TM solution containing Zn and Cu elicitors and report the results of comparative transcriptome analysis of tomato seeds treated with Zn and Cu elicitors. The seeds were treated with optimum concentrations of Bam-FX solutions and subjected to cold methanolic extraction methods to obtain the secondary metabolites produced within them at different time intervals post-Bam-FX treatment. The metabolite mixture was analyzed using gas chromatography-mass spectrometry (GCMS). In transcriptome sequencing, GO and KEGG analyses revealed that the majority of the DEGs in BamFx-treated tomato was associated with primary and secondary metabolism, plant hormone signal transduction, TF regulation, transport, and responses to stimuli.The secondary metabolites found in the BamFX treated tomato seedlings - Esters of Fumaric acid, Succinic acid etc. The transcript levels of most auxin transporter-encoding genes changed significantly in the BamFX-treated seedlings (e.g., Solyc01g007010.3, a RING-type E3 ubiquitin transferase). The gene Solyc07g061720.3 for Gibberellin 2-oxidase and the Phorbol-ester/DAG-type domain-containing protein (Solyc02g068680.1) associated with the intracellular signaling genes were found upregulated in the BamFx-treated seeds. The time-dependent effect of the BamFX (1:500 for 60 min) was found to be regulating Abscisic acid signaling pathway genes (Solyc09g015380.1). This study identified many candidate genes for future functional analyses and laid a theoretical foundation for an improved understanding of the molecular mechanisms involved in the BamFx treatment of tomatoes to improve stress resistance.

Over the years, many different growth media have been used to grow Arabidopsis thaliana in vitro in petri dishes. For these media the nutrient composition may vary, sugars may or may not be added, the medium may or may not be buffered and there is a choice between different gelling agents. The magnitude of possible combinations of these variables obstructs easy comparison of seedling phenotypes grown on the different media. This is especially obvious when it concerns the study of root hairs that are extremely sensitive to changes in their environment. To demonstrate this effect, we have grown Arabidopsis thaliana wild-type seeds on 18 different combinations of growth media and quantified root hair development. Comparison of root hair length and the respective root hair profiles identified the media that result in the formation of the longest root hairs. On these favored media they elongate through tip growth at a constant growth rate until they reach their final length (around 0.6 mm) at a distance of ±4 mm from the root tip.

The HD-Zip family of transcription factors is unique to the plant kingdom, and play roles in modulation of plant growth and response to environmental stresses. R. glutinosa is an important Chinese medicinal material. Its yield and quality are susceptible to various stresses. The HD-Zip transcription factors is unique to the plant, and roles in modulation of plant growth and response to environmental stresses. However, there is no relevant research on the HD-ZIP of R. glutinosa. In this study, 92 HD-Zip transcription factors were identified in R. glutinosa, and denominated as RgHDZ1-RgHDZ92. Members of RgHDZ were classified into four groups (HD-ZipI-IV) based on the phylogenetic relationship of Arabidopsis HD-Zip proteins, and each group contains 38, 18, 17, and 19 members, respectively. Expression analyses of RgHDZ genes based on transcriptome data showed that the expression of these genes could be induced by the endophytic fungus of R. glutinosa. Additionally, we showed that RgHDZ genes were differentially expressed in response to drought, waterlogging, temperature, and salinity treatments. This study provides important information for different expression patterns of stress-responsive HD-Zip and may contribute to the better understanding of the different responses of plants to biotic and abiotic stresses, and provide a molecular basis for the cultivation of resistant varieties of R. glutinosa.

The IRON-REGULATED TRANSPORTER1 (IRT1) is critical for iron uptake in roots, and its exocytosis to the plasma membrane (PM) is regulated by detergent-resistant membranes. However, studies on IRT1 exocytosis and function in response to iron status are limited. Presently, we found that the histidine-rich motif (HRM) of MxIRT1 could bind to iron directly and HRM determined the delivery of MxIRT1 to the PM, after which the cholesterol recognition amino acid consensus (CRAC) motif-regulated MxIRT1 mediated metal transport. IMAC assay revealed that H192 was the vital site for HRM binding to Fe²⁺, and metal-binding activity was stopped after the deletion of HRM (MxIRT1∆HM) or in H192 site-directed mutants (H₁₉₂A). MxIRT1∆HM or H₁₉₂A in transgenic yeast and Arabidopsis failed to localize in the PM and displayed impaired iron absorption. In the PM, Y266 in CRAC was required for metal transport; Y266A transgenic Arabidopsis displayed the same root length, Cd²⁺ flux, and Fe concentration as Arabidopsis mutant irt1 under iron-deficient conditions. Therefore, H192 in HRM may be an iron sensor to regulate delivery of MxIRT1 vesicles to the PM after binding with iron; Y266 in CRAC acts as an iron sensor for active metal transport under iron-deficient conditions.

Plants fix CO₂ into carbohydrates through photosynthesis, and various organisms interact with plants to obtain carbohydrates. Agrobacterium rhizogenes is a soil bacterium known as a plant pathogen that induces hairy root disease. Through A. rhizogenes-plant interactions, transfer-DNA (T-DNA) of the Ri plasmid is inserted into the host plant genome, leading to excessive formation of hairy roots and the synthesis of opines that are carbon and nitrogen sources for A. rhizogenes. In this study, we analyzed the carbohydrate contents in soybean (Glycine max) hairy roots. We found that the starch content was strongly increased in hairy roots, whereas the glucose was significantly decreased. On the other hand, no significant differences were observed in sucrose levels between the main roots and hairy roots of A. rhizogenes-inoculated plants. This result suggests that A. rhizogenes infection caused a change in primary carbon metabolism in the host plant cells.

Arbuscular mycorrhizal (AM) fungi interact with the roots of most land plants and help them to acquire various mineral resources from the soil, including potassium (K⁺). However, tracking K⁺ movement in AM symbiosis remains challenging. Recently, we reported that rubidium can be used as a proxy for K⁺ in mycorrhizal Medicago truncatula. In the present work, we investigated the possibility of using cesium (Cs⁺) as another proxy for K⁺ in AM symbiosis. Plants were placed in growing systems that include a separate compartment only accessible to the AM fungus Rhizophagus irregularis isolate 09 and in which various amounts of cesium chloride (0 mM, 0.5 mM, 1.5 mM, or 3.75 mM) were supplied. Plants were watered with sufficient K⁺ or K⁺-free nutrient solutions, and shoot and root biomass, fungal colonization, and K⁺ and Cs⁺ concentrations were recorded seven weeks after inoculation. Our results indicate that Cs⁺ accumulated in plant tissues only when K⁺ was present in the nutrient solution and when the highest concentration of Cs⁺ was used in the fungal compartment. Consequently, we conclude that Cs⁺ could be used as a proxy for K⁺ in AM symbiosis, but with serious limitations.

Over 40% of arable land in the world is acidic. Al stress has become a global agricultural problem affecting plant growth and limiting crop production in acidic soils. Plants have evolved different regulatory mechanisms of adaptation to exogenous environmental challenges, such as Al stress, by altering their growth patterns. In the past decades, several key genes involved in plant response to Al stress and the mechanism of Al detoxification have been revealed. However, the signaling pathways of plant response to Al stress and the regulatory mechanism of plant Al tolerance remain poorly understood. In this review, we summarized the findings of recent studies on the plant Al tolerance mechanism and the molecular regulation mechanism of phytohormones in response to Al stress. This review improves our understanding of the regulatory mechanisms of plants in response to Al stress and provides a reference for the breeding of Al-tolerant crops.

Cadmium (Cd) causes serious damage to plants. Although calcium (Ca) signal has been found to respond to certain stress, the localization of Ca and molecular mechanisms underlying Ca signal in plants during Cd stress are largely unknown. In this study, Ca²⁺-sensing fluorescent reporter (GCaMP3) transgenic duckweed showed the Ca²⁺ signal response in Lemna turionifera 5511 (duckweed) during Cd stress. Subsequently, the subcellular localization of Ca²⁺ has been studied during Cd stress by transmission electron microscopy, showing the accumulation of Ca²⁺ in vacuoles. Also, Ca²⁺ flow during Cd stress has been measured. At the same time, the effects of exogenous glutamic acid (Glu) and γ-aminobutyric (GABA) on duckweed can better clarify the signal operation mechanism of plants to Cd stress. The molecular mechanism of Ca²⁺ signal responsed during Cd stress showed that Cd treatment promotes the positive response of Ca signaling channels in plant cells, and thus affects the intracellular Ca content. These novel signal studies provided an important Ca²⁺ signal molecular mechanism during Cd stress.

Flowering at an appropriate time is crucial for plant development and reproduction. In Arabidopsis, the flowering process is managed by a regulatory network composed of at least 6 independent pathways. As a core protein in flowering regulation, FLOWERING LOCUS T (FT) participates in almost all these pathways. ANKYRIN REPEAT-CONTAINING PROTEIN 2A (AKR2A) was initially discovered as a 14-3-3-interacting protein. It was then found to be involved in the transportation of chloroplast outer membrane proteins and the resistance to low-temperature stress. Here, we identified an akr2a null mutant with a delayed flowering phenotype. Through the quantitative real-time PCR (qRT-PCR) and bimolecular fluorescence complementation (BiFC) assays, we demonstrated that AKR2A modulates the flowering process through its interaction with FT.