Project description:The Casparian strip constitutes a physical diffusion barrier formed by the polar deposition of lignin in the root endodermis. The polar deposition of lignin is thought to be mediated by the scaffolding activity of membrane bound Casparian Strip domain proteins (CASPs) and the dirigent domain-containing protein Enhanced Suberin1 (ESB1). Here, we show that the endodermis-specific receptor-like kinase (ERK1), is part of this machinery, playing an essential role in the localization of CASP proteins and in the deposition of lignin, which ultimately are required for the formation of afunctional Casparian strip. ERK1 is localized to the cytoplasm and nucleus of the endodermis, and is part of a signalling pathway that implicates the circadian clock regulator Time for Coffee (TIC). In addition, we found that loss of ERK1 and TIC disrupts the Casparian strip organisation and alters composition of the root microbiome.
Project description:The ‘O3-responsive transcriptome’ behavior in the panicles and grains of rice plant was studied individually through high-throughput oligo-DNA microarray technique. Obtained results showed that O3 differentially regulated 620 and 130 genes in the panicles and grains separately, by at least two-fold changes. However, only five genes were found to be common in both the tissues, suggesting towards the tissue specific O3-sensitivity in rice plants. Among the O3-responsive genes, 176 and 444 genes were up- and down-regulated in rice panicle; whereas, 24 and 106 genes in rice grain, respectively. Further mapping onto various regulatory events revealed that, the majority of differentially expressed genes were mainly involved in signaling, hormonal, cell wall, transcription, proteolysis, and defense events. Many previously unknown O3-responsive novel genes were identified, including the brassinosteroid insensitive-1 receptor kinase, wall-associated kinase like receptor, calcium-dependent protein kinases, phosphatidylinositol kinases, G-protein components, ethylene insensitive-3, cellulose synthases, pectatelyase, etc. Inventory of 745 O3-responsive genes and their mapping will surely expand our knowledge on novel regulatory processes in both panicles and grains of rice; and, serve as a resource towards the designing of rice crops for future high-O3 world. Comparison between healthy rice plant panicles and ozone treated plant panicles (for 8 h) and seed (grain) of healthy rice plants and of rice plants grown under ozone for their lifeftime was performed. Three biological replicates (panicle or seed; pooled) were used, and dye-swaped.
Project description:The ‘O3-responsive transcriptome’ behavior in the panicles and grains of rice plant was studied individually through high-throughput oligo-DNA microarray technique. Obtained results showed that O3 differentially regulated 620 and 130 genes in the panicles and grains separately, by at least two-fold changes. However, only five genes were found to be common in both the tissues, suggesting towards the tissue specific O3-sensitivity in rice plants. Among the O3-responsive genes, 176 and 444 genes were up- and down-regulated in rice panicle; whereas, 24 and 106 genes in rice grain, respectively. Further mapping onto various regulatory events revealed that, the majority of differentially expressed genes were mainly involved in signaling, hormonal, cell wall, transcription, proteolysis, and defense events. Many previously unknown O3-responsive novel genes were identified, including the brassinosteroid insensitive-1 receptor kinase, wall-associated kinase like receptor, calcium-dependent protein kinases, phosphatidylinositol kinases, G-protein components, ethylene insensitive-3, cellulose synthases, pectatelyase, etc. Inventory of 745 O3-responsive genes and their mapping will surely expand our knowledge on novel regulatory processes in both panicles and grains of rice; and, serve as a resource towards the designing of rice crops for future high-O3 world.
Project description:Plants have the ability to shed organs that are no longer in use. In Arabidopsis thaliana abscission of floral organs involves cell wall remodeling and cell expansion prior to cell wall dissolution. IDA encodes a secreted peptide that signals through the leucine-rich repeat receptor-like kinases (LRR-RLKs) HAESA (HAE) (At4g28490) and HASEA-LIKE2 (HSL2) (At5g65710).
Project description:Plants have the ability to shed organs that are no longer in use. In Arabidopsis thaliana abscission of floral organs involves cell wall remodeling and cell expansion prior to cell wall dissolution. IDA encodes a secreted peptide that signals through the leucine-rich repeat receptor-like kinases (LRR-RLKs) HAESA (HAE) (At4g28490) and HASEA-LIKE2 (HSL2) (At5g65710).
Project description:The involvement of two R2R3-MYB genes from Pinus taeda L., PtMYB1 and PtMYB8, in phenylpropanoid metabolism and secondary cell wall biogenesis was investigated in planta. These pine MYBs were constitutively overexpressed (OE) in Picea glauca (Moench) Voss, used as a heterologous conifer expression system. Morphological, histological, chemical (lignin and soluble phenols), and transcriptional analyses, i.e. microarray and reverse transcription quantitative PCR (RT-qPCR) were used for extensive phenotyping of MYB-overexpressing spruce plantlets. Upon germination of somatic embryos, root growth was reduced in both transgenics. Enhanced lignin deposition was also a common feature but ectopic secondary cell wall deposition was more strongly associated with PtMYB8-OE. Microarray and RT-qPCR data showed that overexpression of each MYB led to an overlapping up-regulation of many genes encoding phenylpropanoid enzymes involved in lignin monomer synthesis, while misregulation of several cell wall-related genes and other MYB transcription factors was specifically associated with PtMYB8-OE. Together, the results suggest that MYB1 and MYB8 may be part of a conserved transcriptional network involved in secondary cell wall deposition in conifers.
Project description:Diatom cell walls, made of nanostructured silica, are of interest in diverse areas ranging from cellular structure, to hierarchical organization in biomineralization, to nanotechnology. Thus far, only cell surface proteins and proteins tightly associated with silica matrix have been characterized, and essential components of the silica deposition vesicle (SDV) are unknown, including components of the SDV membrane, cytoskeletal-interacting proteins, and proteins involved in trafficking associated with the SDV. Thus, an understanding of most of the molecular components and the dynamics of cellular processes involved in cell wall synthesis is lacking. In this work we report the first whole-cell response analysis using whole genome microarrays to identify genes potentially involved in diverse aspects of diatom cell division or cell wall synthesis. Thalassiosira pseudonana transcript profiles from precise time points, known to be associated with specific cell wall formation processes in cell-cycle synchronized cultures, suggests that this gene set includes extracellular proteins, silica matrix proteins, and proteins involved in signal transduction, vesicle trafficking, and transport. Protein localization experiments further confirm the first discovery of proteins associated with the SDV membrane. We propose that these proteins provide the interface between extra-SDV organization by the cytoskeleton and intra-SDV organization of silica polymerization determinants, which lead to the higher order organization of diatom silica structure.
Project description:Diatom cell walls, made of nanostructured silica, are of interest in diverse areas ranging from cellular structure, to hierarchical organization in biomineralization, to nanotechnology. Thus far, only cell surface proteins and proteins tightly associated with silica matrix have been characterized, and essential components of the silica deposition vesicle (SDV) are unknown, including components of the SDV membrane, cytoskeletal-interacting proteins, and proteins involved in trafficking associated with the SDV. Thus, an understanding of most of the molecular components and the dynamics of cellular processes involved in cell wall synthesis is lacking. In this work we report the first whole-cell response analysis using whole genome microarrays to identify genes potentially involved in diverse aspects of diatom cell division or cell wall synthesis. Thalassiosira pseudonana transcript profiles from precise time points, known to be associated with specific cell wall formation processes in cell-cycle synchronized cultures, suggests that this gene set includes extracellular proteins, silica matrix proteins, and proteins involved in signal transduction, vesicle trafficking, and transport. Protein localization experiments further confirm the first discovery of proteins associated with the SDV membrane. We propose that these proteins provide the interface between extra-SDV organization by the cytoskeleton and intra-SDV organization of silica polymerization determinants, which lead to the higher order organization of diatom silica structure. Analyzed mRNA from 0, 2, 4, 7, 8 and 9 hr of synchronized cell cycle using the Affymetrix GeneChip whole genome tiling array. Initial analysis of gene level expression was performed using Affymetrix Expression Console Software, version 1.1. No biological replicates were performed. 0 hr is used as reference point.
Project description:Transfer cells (TCs) play important roles in facilitating enhanced rates of nutrient transport at key apoplasmic/symplasmic junctions along the nutrient acquisition and transport pathways in plants. TCs achieve this capacity by developing elaborate wall ingrowth networks which serve to increase plasma membrane surface area thus increasing the cell’s surface area-to-volume ratio to achieve increased flux of nutrients across the plasma membrane. Phloem parenchyma (PP) cells of Arabidopsis leaf veins trans-differentiate to become PP TCs which likely function in a two-step phloem loading mechanism by facilitating unloading of photoassimilates into the apoplasm for subsequent energy-dependent uptake into the sieve element/companion cell (SE/CC) complex. We are using PP TCs in Arabidopsis as a genetic model to identify transcription factors involved in coordinating deposition of the wall ingrowth network. Confocal imaging of pseudo-Schiff propidium iodide-stained tissue revealed different profiles of temporal development of wall ingrowth deposition across maturing cotyledons and juvenile leaves, and a basipetal gradient of deposition across mature adult leaves. RNA-Seq analysis was undertaken to identify differentially expressed genes common to these three different profiles of wall ingrowth deposition. This analysis identified 68 transcription factors up-regulated two-fold or more in at least two of the three experimental comparisons, with six of these transcription factors belonging to Clade III of the NAC-domain family. Phenotypic analysis of these NAC genes using insertional mutants revealed significant reductions in levels of wall ingrowth deposition, particularly in a double mutant of NAC056 and NAC018, as well as compromised sucrose-dependent root growth, indicating impaired capacity for phloem loading. Collectively, these results support the proposition that Clade III members of the NAC domain family in Arabidopsis play important roles in regulating wall ingrowth deposition in PP TCs.
Project description:The formation of vascular tissue occurs when cellulose, hemicellulose, lignin and other wall components are deposited within the primary cell wall. These secondary thickened cells then undergo programmed cell death producing a network of empty cells with which water and ions can be transported throughout the plant. The hormones auxin and cytokinin are the principle signals for vascular tissue initiation. As a consequence cells cultured in-vitro can be converted into vascular tissue with the addition of exogenous auxin and cytokinin. We have created an in-vitro cell system, using callus produced from leaves that can be induced to form vascular tissue. Leaves are callused on induction media for two weeks. The callus is then transferred to liquid media and incubated under optimum conditions resulting in an increase in vascular tissue formation. Approximately 20% of cells will differentiate during the incubation period. The alteration of cytokinin concentration affects the ability of the cultured cells to undergo differentiation. Consequently callus incubated in liquid media, containing lower cytokinin concentrations, will undertake relatively little differentiation. Samples have been isolated from cell cultures at different time points and different hormone concentrations during incubation. Quantitative PCR using the marker AtCesA7, which encodes a cellulose synthase subunit specific to secondary wall deposition, was used as a guide to determine periods of high and low vascular differentiation. This system provides an opportunity to compare gene expression between differentiating and non differentiating cells and allow the identification of genes up regulated during vascular tissue formation.