Transcriptional changes in Zea mays seedlings treated with insect elicitor (volicitin).
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ABSTRACT: Insect elicitors, in particular fatty acid amides like volicitin, have been known to induce defense-related gene expression. Here we investigated transcriptional changes in response to volicitin 60min after treatment locally and in distal parts of the treated leaf. 3-Week old Zea mays seedling (inbred line B73) were treated with pure volicitin (1nmol per plant). Controls were untreated. Plants were for 60 min. The second leaf was then taken and a segment of 1 cm cut around the damage site and shock-frozen in liquid N2. 3 segments from 3 individual leaves were pooled for one biological replicate and then stored at -85M-BM-0prior to RNA extraction. For distal gene expression analysis a 1cm segment was cut about 3 cm leaf upwards from the volicitin application site and also frozen in liquid N2. 3 segments from 3 individual leaves were pooled for one biological replicate and then stored at -85M-BM-0prior to RNA extraction. 2 biological replicates were performed for each treatment with one dye swap (second sample).
Project description:Z-3-Hexenol and other green leaf volatiles have been known to induce defense-related gene expression. Here we investigated the early transcriptional changes in response to Z-3-hexenol. 3-week-old Zea mays seedling (inbred line B73) was exposed to pure Z-3-hexenol (1.5 μM) in a glass cylinder. Controls were treated likewise without the addition of Z-3-hexenol. Plants were exposed for 20 min and 60 min. The second leaf was then cut and shock-frozen in liquid N2 and then stored at -85°prior to RNA extraction. 3 individual leaves were pooled for 1 biological replicate. 3 biological replicates were performed for each treatment, with one dye swap (second sample).
Project description:Anthracnose caused by the ascomycete Colletotrichum graminicola is one of the most severe fungal diseases of Zea maize. Cultivars with different levels of resistance have been described. However, which genes contribute to cultivar-specific constitutive and/or induced defense in this economically important pathosystem is still elusive. Transcriptome analyses of infected maize leaves of varieties Golden Jubilee (GJ) and B73 by RNA-Seq was performed for the penetration, biotrophic and necrotrophic phases.
Project description:C4 grasses, such as maize (Zea mays), have high photosynthetic efficiency through combined biochemical and structural adaptations.C4 photosynthesis is established along the developmental axis of the leafblade, leading from an undifferentiated leaf base just above the ligule into highly specialized mesophyll cells (MCs) and bundle sheath cells (BSCs) at the tip. To resolve the kinetics of maize leaf development and C4 differentiation and to obtain a systems-level understanding of maize leaf formation, the accumulation profiles of proteomes of the leaf and the isolated BSCs with their vascular bundle along the developmental gradient were determined using large-scale mass spectrometry. This was complemented by extensive qualitative and quantitative microscopy analysis of structural features (e.g., Kranz anatomy, plasmodesmata, cell wall, and organelles). More than 4300 proteins were identified and functionally annotated. Developmental protein accumulation profiles and hierarchical cluster analysis then determined the kinetics of organelle biogenesis, formation of cellular structures, metabolism, and coexpression patterns. Two main expression clusters were observed, each divided in subclusters, suggesting that a limited number of developmental regulatory networks organize concerted protein accumulation along the leaf gradient. The coexpression with BSC and MC markers provided strong candidates for further analysis of C4 specialization, in particular transporters and biogenesis factors. Based on the integrated information, we describe five developmental transitions that provide a conceptual and practical template for further analysis. An online protein expression viewer is provided through the PlantProteomeDatabase.
Project description:Purpose: To study the effects of drought at the transcriptomic level on two different actively dividing maize tissue: the ovaries, and the leaf meristem Methods: The Illumina reads were mapped to the maize B73 reference genome using Tophat followed by transcriptome reconstruction using Cufflinks. The FPKM valuse were extracted from cufflinks output and an R package called Limma was used to identify differentially expressed genes under drought under both tissues Results and Conclusions: Different processes which were differentially expressed under drought in both tissues were identified and analyzed in detail. A working hypothesis was formulated to account for the observed susceptibility of the reproductive tissue when compared to the robust response of the vegetative tissue. This analysis also servers as a basis for future study on drought-induced embryo abortion. Maize (Zea mays) plants of inbred line B73 were grown in the green house under well watered and drought stress conditions until they reached the reproductive stage (at the onset of silk emergence). For the drought stress two to three days after irrigation was withheld, the plants were hand pollinated, and 24 hours after pollination measurements and samples were collected for transcriptome analysis. At the end of the drought period (1DAP) the basal leaf meristem of the three youngest leaves and the ovary tissues were sampled for Illumina deep sequencing. Samples were labeled as well watered control leaf meristem (MLC), well watered control ovaries/ "cob" (MCC), drought stressed leaf meristem (MLD) and drought stressed ovary tissue (MCD). There are 8 libraries in total including one biological replicate for each condition.
Project description:The metabolic response of maize source leaves to low nitrogen supply was analyzed in maize seedlings by parallel measurements of transcriptome and metabolome profiling. Inbred lines A188 and B73 were cultivated under controlled growth chamber conditions and supplied with either sufficient (15mM) or limiting (0.15mM) nitrate supply. Leaf lamina material was harvested at day 20 and day 30 after germination with the fifth and sixth leaf representing the main source leaf respectively. Four replicates were collecetd from individual plants for each combination of genotype, growth stage and nitrogen treatment. The leaf material was frozen, homogenised and aliquoted for transcriptome and metabolome analysis. The molecular data was further supplemented by phenotypic characterisation of the maize seedlings under investigation. Limited availability of nitrogen caused strong shifts in the metabolite profile of leaves. The transcriptome was less affected by the nitrogen stress but showed strong genotype and age dependent patterns. Nitrogen starvation initiated the selective down-regulation of processes involved in nitrate reduction and amino acid assimilation; ammonium assimilation related transcripts on the other hand were not influenced. Carbon assimilation related transcripts were characterized by high transcriptional coordination and general down-regulation under low nitrogen conditions. Nitrogen deprivation caused a slight accumulation of starch, but also directed increased amounts of carbohydrates into the cell wall and secondary metabolites. The decrease in N availability also resulted in accumulation of phosphate and by strong down-regulation of genes usually involved in phosphate starvation response, underlining the great importance of phosphate homeostasis control under stress conditions. Maize inbred lines A188 and B73 were cultivated in pots containing nutrient poor peat soil under the controlled conditions of a growth chamber. The plants were fertilized with modified Hoagland solutions containing either 15mM (high N) or 0.15mM nitrate (low N). Source leaf lamina were harvested at day 20 and day 30 after start of germination for parallel analysis of transcriptome and metabolome profiles. The molecular data is further supplemented by phenotypic characterization of the maize seedlings under investigation.
Project description:We analysed genome-wide histone H3 lysine 4 trimethylation and histone H3 lysine 9 acetylation, two modifications typically associated with active genes, in meristematic cells at the base and expanding cells in the maturing zone of the maize (Zea mays) leaf. These data were compared to transcript levels of associated genes. Our data revealed that for individual genes fold-changes in histone modification and transcript abundance were much better correlated than absolute intensities. When focusing on regulated modification sites, we identified secondary upstream H3 lysine 9 acetylation peaks (SUPs) on upstream promoter regions of approximately 6% of all acetylated genes. SUPs showed stronger regulation than the previously described acetylation peaks at transcription initiation sites, were more often found on genes that were upregulated towards the maturing zone than on downregulated genes, and were significantly enriched on photosynthetic genes. We identified SUPs on all genes encoding enzymes of the C4 cycle. Moreover, SUPs were enriched in four lists of candidate C4-associated genes that were derived from previous transcriptomic studies. Based on these data, we used highly regulated SUPs as an epigenetic mark to identify new genes potentially involved in C4 metabolism. This approach also allowed the identification of ethylene response elements as highly enriched cis-acting elements in SUP regions. Our data suggest co-evolution of epigenetic promoter elements during the establishment of C4 photosynthesis. Comparative analysis of H3K9ac, H3K4me3 and the transcription between two developmental zones within one maize leaf.
Project description:Aerenchyma is a specialized tissue consisting of longitudinal gas spaces, which enables internal movement of gases (e.g., O2, CO2, ethylene and methane), in plant roots, petioles and stems. Especially, internal transport of oxygen via aerenchyma from shoots to roots is very important for adaptation or survival of plants under waterlogged condition. To identify aerenchyma formation-associated genes expressed in maize root, we used LM combined with a microarray for monitoring genes expressed in root cortical cells under three conditions: under aerobic condition and under waterlogged condition with and without pretreatment with 1-MCP, an inhibitor of ethylene perception. For the waterlogging treatments, the primary root (but not the shoots) was waterlogged. Two and half day-old-seedlings were pre-treated with an inhibitor of ethylene perception 1-methylcyclopropene (1-MCP; 1 ppm) for 12 hours before the waterlogging treatment. Three-day-old seedlings were growing under aerated condition at the same time with other treatments as a control. Total RNA was extracted from root cortex cells from the segment of the primary root, 0.5 cm long: from 1.5 to 2 cm from the junction shoot-root derived from 3-days-old maize seedlings, and subjected to 44k oligo-DNA microarray (1. Aerated vs Hypoxia, 2. Hypoxia+MCP vs Hypoxia) with 3 biological replicates and color swaps.
Project description:To identificate long noncoding RNAs in maize, we profiled transcriptome of shoots and roots using non-directional paired-end RNA-seq based on poly(A) selection. Transcriptom profiling in maize shoots and roots.
Project description:To identificate long noncoding RNAs in maize, we profiled transcriptome of shoots and roots using stranded single-end RNA-seq based on poly(A) selection. Transcriptom profiling in maize shoots and roots.
Project description:To investigate the developmental gradient of the third maize leaf, the light exposed area of the leaf (corresponding to 18cm of leaf) and 2cm shaded by the sheath were sampled in ten slices. Four replicates were collected, immediately shock frozen in liquid nitrogen and subsequently cut into 2cm slices. At least 10 plants were pooled for each biological replicate. We have systematically analyzed a developmental gradient of the third maize leaf from the point of emergence into the light to the tip in ten continuous leaf slices to study organ development and physiological and biochemical functions. Transcriptome analysis, oxygen sensitivity of photosynthesis, delta-13C values, and photosynthetic rate measurements showed that the maize leaf undergoes a sink to source transition without an intermediate phase of C3 photosynthesis or operation of a photorespiratory carbon pump. Metabolome and transcriptome analysis, chlorophyll and protein measurements, as well as dry weight determination showed continuous gradients for all analyzed items. The absence of binary on-off switches and regulons pointed to a morphogradient along the leaf as the determining factor of developmental stage. Analysis of transcription factors for differential expression along the leaf gradient defined a list of putative regulators orchestrating the sink-to-source transition and establishment of C4 photosynthesis. Finally, transcriptome and metabolome analysis, as well as enzyme activity measurements, and absolute quantification of selected metabolites revised the current model of maize C4 photosynthesis. All datasets are included within the publication to serve as a resource for maize leaf systems biology. For the transcriptional analysis, the goal of the study was to (i) identify whether the leaf contains binary switches for genes involved in photosynthesis, (ii)characterize the patterns of gene expression in the leaf, (iii) provide independent validation of maize leaf expression experiments published in Li et al. (2011) and (iv) determine transcripts co-expressed with key transcripts of C4 photosynthesis. To this end, changed transcripts were determined by ANOVA and characterized by K-means and hierachical clustering. Four replicates were collected for each of the ten consecutive leaf slices resulting in 40 one color arrays. Slice 1 represents the tip of the leaf, slice 10 the lowermost slice which is shaded by the sheath with all slices in between consecutively numbered.