Project description:Despite the major physiological dissimilarities between roots and their tips, differences in their gene expression profiles remain largely unexplored. In this research, the transcriptome of rice (Oryza sativa L. subsp. Japonica) mature root tissue and root tips was monitored using mRNA-Seq at 2 time points. Almost 50 million 76 bp reads were mapped onto the rice genome sequence, differential expression patterns between tissues and time points were investigated and at least 1,006 novel transcriptionally active regions (nTARs) were detected to be expressed in rice root tissue. More than 30,000 genes were found to be expressed in rice roots, among which 1,761 root-specific and 306 tip-specific transcripts. Mature root tissue appears to respond more strongly to external stimuli than tips, showing a higher expression of for instance auxin responsive and ABA-responsive genes, as well as the phenylpropanoid pathway and photosynthesis upon light. The root tip-specific transcripts are mainly involved in mitochondrial electron transport, organelle development, secondary metabolism, DNA replication and metabolism, translation, and cellular component organization. As roots developed, genes involved in electron transport, response to oxidative stress, protein phosphorylation and metabolic processes were activated. For some nTARs a potential role in root development can be put forward based on homology to genes involved in CLAVATA signaling, cell cycle regulators and hormone signaling. A subset of differentially expressed genes and novel transcripts was confirmed using (q)RT-PCR. These results uncover previously unrecognized tissue-specific expression profiles and provide an interesting starting point to study the different regulation of transcribed regions of these tissues. 2 biological replicates of roots and 3 biological replicates of root tips were sampled at two time points (1 biological replicate contains pooled tissue from 6 plants)
Project description:Despite the major physiological dissimilarities between roots and their tips, differences in their gene expression profiles remain largely unexplored. In this research, the transcriptome of rice (Oryza sativa L. subsp. Japonica) mature root tissue and root tips was monitored using mRNA-Seq at 2 time points. Almost 50 million 76 bp reads were mapped onto the rice genome sequence, differential expression patterns between tissues and time points were investigated and at least 1,006 novel transcriptionally active regions (nTARs) were detected to be expressed in rice root tissue. More than 30,000 genes were found to be expressed in rice roots, among which 1,761 root-specific and 306 tip-specific transcripts. Mature root tissue appears to respond more strongly to external stimuli than tips, showing a higher expression of for instance auxin responsive and ABA-responsive genes, as well as the phenylpropanoid pathway and photosynthesis upon light. The root tip-specific transcripts are mainly involved in mitochondrial electron transport, organelle development, secondary metabolism, DNA replication and metabolism, translation, and cellular component organization. As roots developed, genes involved in electron transport, response to oxidative stress, protein phosphorylation and metabolic processes were activated. For some nTARs a potential role in root development can be put forward based on homology to genes involved in CLAVATA signaling, cell cycle regulators and hormone signaling. A subset of differentially expressed genes and novel transcripts was confirmed using (q)RT-PCR. These results uncover previously unrecognized tissue-specific expression profiles and provide an interesting starting point to study the different regulation of transcribed regions of these tissues.
Project description:The aim of this study was to determine the changes in gene expression of rice root tips when they came in to contact with a hard layer (60% wax layer). Three categories of root tips were sampled; tips before the hard layer, tips that had come into contact with the hard layer and root tips which had buckled after coming into contact with the hard layer. Two genotypes (Azucena and Bala) that vary in there ability to penetrate a hard layer were selected for a genotype comparison of gene expression at the hard layer. Keywords: Genotype comparison, root impedance response
Project description:Biotrophic plant pathogens have evolved sophisticated strategies to manipulate their host. They derive all of their nutrients from living plant tissues, by making intimate contact with their host while avoiding a resistance response. Rice is one of the most important crop plants worldwide and an excellent model system for studying monocotyledonous plants. Estimates of annual yield losses due to plant-parasitic nematodes on this crop range from 10 to 25% worldwide. One of the agronomically most important nematodes attacking rice is the rice root knot nematode Meloidogyne graminicola. Attack of plant roots by sedentary plant parasitic nematodes, like the root knot nematodes (RKN; Meloidogyne spp.) involves the development of specialized feeding cells in the vascular tissue. The second stage juvenile of the RKN punctures selected vascular cells with its stylet, injects pharyngeal secretions, and this ultimately leads to the reorganisation of these cells into typical feeding structures called giant cells (GCs), from which the nematode feeds for the remainder of its sedentary life cycle (Gheysen & Mitchum, 2011). Morphological and physiological reprogramming of the initial feeding cell leads to nucleus enlargement, proliferation of mitochondria and plastids, metabolic activation, cell cycle alterations and cell wall changes (Gheysen and Mitchum, 2011). The hyperplasia and hypertrophy of the surrounding cells leads to the formation of a root gall, which is typically formed at the root tips in the case of the rice RKN M. graminicola. In comparison with other RKN, M. graminicola has a very fast life cycle, with swelling of the root tips observed as early as 1 day after infection (dai). At 3 dai, terminal hook-like galls are clearly visible (Bridge et al., 2005). After 3 moults the nematodes are mature, around 10 dai. The M. graminicola females lay their eggs inside the galls, while most other RKN deposit egg masses at the gall surface, and hatched juveniles can reinfect the same or adjacent roots. In well-drained soil at 22-29 degrees C the life cycle of M. graminicola is completed in 19 days. 2 biological replicates of nematode infected giant cells and control vascular cells were sampled at two time points: 7 and 14 dai
Project description:Gene expression profile of response to auxin at 3 h after treatment in rice root tips: IR64 (loss-of-function of DRO1 type) vs Near-isogenic line homozygous for the Kinandang Patong allele of DRO1 in an IR64 genetic background (Dro1-NIL; gain-of-function of DRO1 type) We used two rice varieties, IR64 and near-isogenic line homozygous for the Kinandang Patong allele of DRO1 in an IR64 genetic background (Dro1-NIL). We performed comprehensive microarray analysis of rice root tips with auxin treatment (3h) and pre-treatment (0h) in IR64 and Dro1-NIL. Seedling root tips of IR64 and Dro1-NIL were treated with 10 M-BM-5M 2,4-D. n = 3 biological repeats (15 seedlings per repeat).
Project description:In this study a comparison was made between the local transcriptional changes at two time points upon root knot (Meloidogyne graminicola) and migratory nematode (Hirschmanniella oryzae) infection in rice. Using mRNA-Seq we have characterized specific and general responses of the root challenged with these endoparastic root nematodes with very different modes of action. Root knot nematodes induce major developmental reprogramming of the root tip, where they force the cortical cells to form multinucleate giant cells, resulting in gall-development. Our results show that root knot nematodes force the plant to produce and transfer nutrients, like sugars and amino acids, to this tissue. Migratory nematodes, on the other hand, induce the expression of proteins involved in plant death and oxidative stress, and obstruct the normal metabolic activity of the root. While migratory nematode infection also causes upregulation of biotic stress-related genes early in the infection, the root knot nematodes seem to actively suppress the local defence of the plant root. This is exemplified by a downregulation of genes involved in the salicylic acid and ethylene pathways. Interestingly, hormone pathways usually involved in plant development, were strongly induced (auxin and gibberellin) or repressed (cytokinin) in the galls. In addition, thousands of novel transcriptionally active regions as well as highly expressed nematode transcripts were detected in the infected root tissues. These results uncover previously unrecognized nematode-specific expression profiles and provide an interesting starting point to study the physiological function of many yet unannotated transcripts potentially targeted by these nematodes. 2 or 3 biological replicates of nematode infected roots and root tips and their respective controls were sampled at two time points (1 biological replicate contains pooled tissue from 6 plants)
Project description:High-throughput sequencing of small RNAs from rice was used to identify distinct miRNAs that are responsive to elicitors from the fungal pathogen Magnaporthe oryzae. [Expression profiling by array] We used microarrays to determine the expression behaviour of target genes for elicitor-regulated miRNAs. [High throughput sequencing] High-throughput sequencing of rice small RNAs was performed in two different tissues, leaves and roots, and two different time point of elicitor treatment, 30' and 2h Amplicons were prepared by 5M-BM-4and 3M-BM-4adaptor ligation in which the 5'-adaptor contained a 'barcode' consisting of a 4-nucleotide identifier sequence for each sample. The libraries containing unique barcodes were combined and subjected to pyrosequencing (454 Life SciencesTM, Roche) [Expression profiling by array] Leaves from rice plants were harvested at two time points after the onset of treatment (30' and 2h) with elicitors of Magnaporthe oryzae 18.1 and used for RNA extraction and hybridization on Affymetrix microarrays. Mock inoculations were performed with sterile water for control experiments. Three biological replicates were analyzed. Each sample represented a pool of approximately 150 rice plants. [High throughput sequencing] 8 samples examined: leaves and roots, treated or not with elicitors at two different time points, 30' and 2h (2x2x2)
Project description:Col-0 and WEE1KO (wee1-1 and wee1-2) were germinated on control medium on a nylon mesh and transferred 5 days after germination to control medium. Samples were harvested at three different time points after transfer: 0 h, 5 h, and 24 h. All sampling points were performed in four independent experiments for Col-0, two independent experiments for wee1-1 and two independent experiments for wee1-2. For each time point in each experiment ᄆ50 root tips were collected and frozen in liquid nitrogen. RNA was extracted from root tissue with TriZol reagent (Invitrogen) and purified with RNneasy kit (Qiagen). The RNA of two independent experiments for Col-0 and WEE1KO were subsequently pooled and used for microarray analysis.
Project description:Col-0 and WEE1KO (wee1-1 and wee1-2) were germinated on control medium on a nylon mesh and transferred 5 days after germination to medium supplemented with 2 mM HU. Samples were harvested at three different time points after transfer: 0 h, 5 h, and 24 h. All sampling points were performed in four independent experiments for Col-0, two independent experiments for wee1-1 and 2 independent experiments for wee1-2. For each time point in each experiment ᄆ50 root tips were collected and frozen in liquid nitrogen. RNA was extracted from root tissue with TriZol reagent (Invitrogen) and purified with RNneasy kit (Qiagen). The RNA of two independent experiments for Col-0 and WEE1KO were subsequently pooled and used for<br>microarray analysis.
Project description:For transcript analysis of aluminum tolerance responses in Medicago truncatula we compared transcripts from 2.5 µM Al-treated and control (-Al) root tips corresponding to 12 and 48 h after Al treatment in Al-tolerant (T32) and Al-sensitive (S70) lines. Keywords: 2 time points and 2 lines