Project description:Identification of the earliest transcriptional responses of adult Arabidopsis plant roots towards N-deprivation. Hydroponically grown Plants (35 days old) were 5 days adapted to nitrate or ammonium,respectively, as sole N-source to detect N-form specific transcripts. 24 Samples: 2 Pre-Treatments (5 Day adaptation to 3mM Ammonium/Nitrate) x 3 sampling time-points (0min, 15 min, 180 min) x 3 independent replications per time-point + 6 additional controls (2 x 15min, 1x 180min per Pre-Treatment)
Project description:Multigene families encoding diverse secreted peptide hormones play important roles in plant development. A need exists to efficiently elucidate the structures and post-translational-modifications of these difficult-to-isolate peptide hormones in planta so that their biological functions can be determined. A mass spectrometry and bioinformatics approach was developed to comprehensively analyse the secreted peptidome of Medicago hairy root cultures and xylem sap. We identified 759 spectra corresponding to the secreted products of twelve peptide hormones including four CEP (C-TERMINALLY ENCODED PEPTIDE), two CLE (CLV3/ENDOSPERM SURROUNDING REGION RELATED) and six XAP (XYLEM SAP ASSOCIATED PEPTIDE) peptides. The MtCEP1, MtCEP2, MtCEP5 and MtCEP8 peptides identified differed in post-translational-modifications. Most were hydroxylated at conserved proline residues but some MtCEP1 derivatives were tri-arabinosylated. In addition, many CEP peptides possessed unexpected N- and C-terminal extensions. The pattern of these extensions suggested roles for endo- and exoproteases in CEP peptide maturation. Longer -than -expected, hydroxylated and homogeneously modified mono- and tri-arabinosylated CEP peptides corresponding to their in vivo structures were chemically synthesised to probe the effect of these post-translational-modifications on function. The ability of CEP peptides to elevate root nodule number was increased by hydroxylation at key positions. MtCEP1 peptides with N-terminal extensions or with tri-arabinosylation modification, however, were unable to impart increased nodulation. The MtCLE5 and MtCLE17 peptides identified were of precise size, and inhibited main root growth and increased lateral root number. Six XAP peptides, each beginning with a conserved DY sulfation motif, were identified including MtXAP1a, MtXAP1b, MtXAP1c, MtXAP3, MtXAP5 and MtXAP7. MtXAP1a and MtXAP5 inhibited lateral root emergence. Transcriptional analyses demonstrated peptide hormone gene expression in the root vasculature and tip. Since hairy roots can be induced on many plants, their corresponding root cultures may represent ideal source materials to efficiently identify diverse peptide hormones in vivo in a broad range of species.
Project description:TIFY is a large plant-specific transcription factor gene family. A subgroup of TIFY genes named JAZ (Jasmonate-ZIM domain) has been identified as repressors of jasmonate (JA)-regulated transcription in Arabidopsis and other plants. JA signaling is involved in many aspects of plant growth/development and in the defense responses to biotic and abiotic stresses. Here we identified the TIFY genes (designated as PvTIFY) from the legume common bean (Phaseolus vulgaris) and functionally characterized PvTIFY10C as a transcriptional regulator. Twenty-three genes from the PvTIFY gene family were identified through whole genome sequence analysis. Most of these were induced upon methyl-JA elicitation. We selected PvTIFY10C as a representative JA-responsive PvTIFY gene for further functional analysis. Transcriptome analysis via microarray hybridization using the designed Bean Custom Array 90K was performed in transgenic roots of composite plants with modulated -RNAi-silencing or over-expression- PvTIFY10C gene expression. Data were interpreted using Mapman adapted to common bean. Microarray differential gene expression data were validated by real-time qRT-PCR expression analysis. Comparative global gene expression analysis revealed opposite regulatory changes in processes such as RNA and protein regulation, stress response and metabolism in silenced vs. over-expressing roots. These data point to transcript reprogramming -mainly repression- orchestrated by PvTIFY10C. In addition we found that several PvTIFY genes as well as genes from the JA biosynthetic pathway responded to P-deficiency. Relevant P-responsive genes that participate in carbon metabolic pathways, cell wall synthesis, lipid metabolism, transport, DNA, RNA and protein regulation, signaling, were oppositely-regulated in control vs. PvTIFY10C silenced roots. These data indicate that PvTIFY10C regulates, directly or indirectly, gene expression of some P-responsive genes something that could be mediated by JA-signaling. Our work contributed to the functional characterization of PvTIFY transcriptional regulators in common bean, an agronomically important legume. Members from the large PvTIFY gene family are important global transcriptional regulators that could participate as repressors of the JA signaling pathway. In addition we propose that the JA-signaling pathway that involves PvTIFY genes might play a role in regulating the plant response / adaptation to P-starvation.
Project description:Pattern of gene expression of M. mazei in response to 10 uM bismuth nitrate was analyzed relative to gene expression pattern of M. mazei grown in the presence of 30 uM potassium nitrate (control cultures). Therefore, five pre-cultures of M. mazei was grown to mid-exponential growth-phase. Then, the pre-cultures were divided into aliquotes, one half spiked with bismuth nitrate and the other half with potassium nitrate (control) to match nitrate concentration of the bismuth spike. Samples were propagated for two days. Then, total RNA was isolated and transformed into Cy3 or Cy5 labeled cDNA. Labeled cDNA derived from one culture treated with bismuth and from one control culture, both obtained from the same pre-culture, was hybridized with microarray chips. Hybridized chips were scanned, derived data processed and relative expression levels of orfs from M. mazei in response to bismuth calculated.
Project description:Bacillus thuringiensis, a well-known and effective bio-insecticide, has attracted considerable attention as a potential biological control agent for the suppression of plant diseases. Treatment of tomato roots with a filter-sterilized cell-free filtrate (CF) of B. thuringiensis systemically suppresses bacterial wilt caused by Ralstonia solanacearum through systemic activation of the plant defense system. Comparative analysis of the expression of the Pathogenesis-Related 1(P6) [PR-1(P6)] gene, a marker for induced resistance to pathogens, in various tissues of tomato plants treated with CF on their roots suggested that the B. thuringiensis-induced defense system was activated in the leaf, stem, and main root tissues, but not in the lateral root tissue. At the same time, the growth of R. solanacearum was significantly suppressed in the CF-treated main root tissue but not in the CF-treated lateral root tissue. This distinct activation of the defense reaction and suppression of R. solanacearum were reflected by the differences in the transcriptional profiles of the main and lateral tissues in response to the CF. In the CF-treated main root tissue, but not CF-treated lateral root tissue, the expression of several salicylic acid (SA)-responsive defense-related genes was specifically induced, whereas jasmonic acid (JA)-related gene expression was either down-regulated or not induced in response to the CF. On the other hand, genes encoding ethylene (ET)-related proteins were induced equally in both the main and lateral root tissues. Taken together, the co-activation of SA-dependent signaling pathway with ET-dependent signaling pathway and suppression of JA-dependent signaling pathway may play key roles in B. thuringiensis-induced resistance to R. solanacearum in tomato plants. Gene expression was measured in main and lateral root tissues of tomato treated with Bacillus thuringiensis or distilled water-treated control at 48 hours after treatment. Two independent experiments were performed at each tissue (main root or lateral root tissue) for each treatment (Bacillus thuringiensis or distilled water control).
Project description:affy_ralstonia_peeters_medicago - We have identified two essential virulence determinants (GALA7, a type III secretion effector and HpaP, a chaperone-like protein) of Ralstonia solanacearum for the infection and colonisation of the host plant Medicago truncatula. The scope of this project is to identify the GALA7 and HpaP-specific transcriptome alteration. For this purpose wild type and mutant infected root material (13h and 72h postinfection) will be analysed on M. truncatula affymetrix chips. Medicago truncatula (A17 line) are grown in vitro on Farheus medium (with Nitrogen source) plantlets are inoculated with water R. solanacearum wt, gala7 and hpap mutants, and root tips are collected at 13h and 72h postinoculation. Experiment was performed 3 times independently. 4 bacteria conditions x 2 harvest times x 3 biological repeats = 24 samples Keywords: gene knock out,normal vs disease comparison,time course,treated vs untreated comparison 24 arrays - Medicago
Project description:Organic acid secretion is a widespread physiological response of plants to alkalinity. However, the features of alkali-induced secretion of organic acid and the underlying mechanism are poorly understood. Herein, it was indicated that oxalate was the main organic acid synthesized and secreted in vine roots, and acetate synthesis and malate secretion were also promoted under NaHCO3 stress. NaHCO3 stress enhanced H+ efflux rate of vine roots, which was related to plasma membrane H+-ATPase activity. Transcriptomic profiling revealed that carbohydrate metabolism was the most significantly altered biological process under NaHCO3 stress; a total of seven genes related to organic acid metabolism were significantly altered, including two PEPCs and PEPCKs. Additionally, the expression levels of five ABC transporters, particularly ABCB19, as well as two malate transporter ALMT2s, were largely upregulated by NaHCO3 stress. Phosphoproteomic profiling demonstrated that the altered phosphoproteins were primarily related to binding, catalytic activity and transporter activity in light of their molecular functions. The phosphorylation levels of PEPC3, two plasma membrane H+-ATPases 4 and ABC transporters ABCB19 and PDR12 were significantly increased. Additionally, the inhibition of ethylene synthesis and perception completely blocked NaHCO3-induced organic acid secretion, while the inhibition of IAA synthesis reduced NaHCO3-induced organic acid secretion. Collectively, our results demonstrated oxalate as the main organic acid under alkali stress and the necessity of ethylene in mediating organic acid secretion, as well as further identified several candidate genes and phosphoproteins responsible for organic acid metabolism and secretion.
Project description:Plants of the resistant Pisum sativum subsp. syriacum accession P665 and the susceptible pea cultivar Messire were inoculated with M. pinodes.The experiment was conducted in three replicates. 16, 24 and 48 hours after inoculation RNA was isolated from leaves of infected plants and transcribed into cDNA. For each time point and replicate, Cy-labelled cDNA samples from resistant and susceptible plants were mixed and hybridized to Mt16kOLI1Plus microarray
Project description:Drought stress response is a complex trait regulated at multiple levels. In the past few years, molecular and genomic studies have shown that several drought responsive genes (DRGs) with various functions are induced by drought stresses, and that various transcription factors (TFs) are involved in the regulation of stress-inducible genes. In addition to those DRGs mentioned above, microRNAs (miRNAs) are important regulators of gene expression at the posttranscriptional level by repressing mRNA expression. There is a complex interplay between transcriptional and post-transcriptional regulation of drought response that has not been extensively characterized in tobacco. In order to fully understand DRGs (including TFs) and different roles of miRNAs involved in the stress response, we sequenced and analysed three Digital Gene Expression (DGE) libraries in roots from drought treated tobacco plants, and four small RNA populations in roots, stems and leaves from control or drought treated tobacco plants. We identified 276 candidate DRGs in tobacco with sequence similarities to 64 known DRGs from model plants and crops and about 40% were TFs including WRKY, NAC, ERF and bZIP families. Furthermore, Out of these tobacco DRGs, 54differentially expressed DRGs included 21 TFs, which belonged to 24 TFs families such as NAC (6), MYB (4), ERF (10) and bZIP (1). Additionally, we confirmed expression of 39 known miRNA families (122 members) and five conserved miRNA families, which showed differential regulation under drought stress. Targets of miRNAs were further surveyed based on a recently published study, in which ten targets were DRGs. Finally, an integrated gene regulatory network has been proposed for the molecular mechanisms of the response of tobacco roots to drought stress using differentially expressed DRGs, the changed expression proﬁles of miRNAs and their target transcripts as a basis base on previous studies. In general, our data provide valuable information for future studies of the molecular mechanisms underlying tobacco roots in response to drought resistance in tobacco and other plants. Three tobacco (Nicotiana tabacum L.) roots tag-based DGE libraries treated at three time points (0, 6 and 48 h) with 20% PEG6000 were generated using Illumina 1G technology. The samples for four small RNA libraries was used based on the result of physiological index measurement as follows: equal quantities (10 ug) of total RNA isolated from tobacco roots treated with two time points (6 and 48 h) were mixed together to construct the drought -treated small RNA library (Root-treat), and total RNA prepared from the control roots sample was used to construct the control small RNA library (Root-ck). In addition, we also constructed another two libraries (stem and leaf) from leaves and stems of control plants, respectively. These libraries were constructed using the Small RNA Sample Prep Kit (Illumina, San Diego, CA) and then sent for Solexa sequencing.
Project description:Broad-host root endophytes establish long-term interactions with a large variety of plants, thereby playing a significant role in natural and managed ecosystems and in evolution of land plants. To exploit plants as living substrates and to establish a compatible interaction with morphologically and biochemically extremely different hosts, endophytes must respond and adapt to different plant signals and host metabolic states. Here we identified host-adapted colonization strategies and host-specific effector candidates of the mutualistic root endophyte Piriformospora indica by a global investigation of fungal transcriptional responses to barley and Arabidopsis at different symbiotic stages. Additionally we examined the role played by nitrogen in these two diverse associations. Cytological studies and colonization analyses of a barley mutant and fungal RNAi strains show that distinct physiological and metabolic signals regulate host-specific lifestyle in P. indica. This is the foundation for exploring how distinct fungal and host symbiosis determinants modulate biotrophy in one host and saprotrophy in another host and, ultimately, gives hints into the mechanisms underlying host adaptation in root symbioses. Arabidopsis and barley roots were inoculated with Piriformospora indica and grown for 14 days. Additionally P. indica was grown on 1/10 PNM medium alone. Samples were taken 3 and 14 dpi (Arabidopsis), 14 dpi (barley) and 3dpi (1/10 PNM). Each experiment was performed in three independent biological repetitions. Piriformospora indica gene expression examined only.