Project description:Internal aeration is crucial for root growth in waterlogged soil. A barrier to radial oxygen loss (ROL) can enhance long- distance oxygen transport via the aerenchyma to the root tip; a higher oxygen concentration at the apex enables root growth into anoxic soil. The ROL barrier is formed within the outer part of roots (OPR). Suberin and/or lignin depos- ited in cell walls are thought to contribute to the barrier, but it is unclear which compound is the main constituent. This study describes gene expression profiles during ROL barrier formation in rice roots to determine the relative responses of suberin and/or lignin biosyntheses for the barrier. OPR tissues were isolated by laser microdissection and their transcripts were analysed by microarray. A total of 128 genes were significantly up- or downregulated in the OPR during the barrier formation. Genes associated with suberin biosynthesis were strongly upregulated, whereas genes associated with lignin biosynthesis were not. By an ab initio analysis of the promoters of the upregulated genes, the putative cis-elements that could be associated with transcription factors, WRKY, AP2/ERF, NAC, bZIP, MYB, CBT/DREB, and MADS, were elucidated. They were particularly associated with the expression of transcrip- tion factor genes containing WRKY, AP2, and MYB domains. A semiquantitative reverse-transcription PCR analysis of genes associated with suberin biosynthesis (WRKY, CYP, and GPAT) confirmed that they were highly expressed during ROL barrier formation. Overall, these results suggest that suberin is a major constituent of the ROL barrier in roots of rice. 23-d-old plants were either continued in aerated solution or transplanted into N2-flushed or stagnant deoxygenated solution for 9 h. After treating the roots of plants in aerated, stagnant, or N2-flushed conditions for 9h, the basal parts (12.5 -22.5mm below the root - shoot junction) of the adventitious roots were collected. Cells in OPR (including exodermis and sclerenchyma) were isolated using laser microdissection. RNA extracted from the isolated OPR was analysed with a 44k rice oligo-DNA microarray. Total RNAs were labeled with a Quick Amp Labeling Kit (Agilent Technologies) according to the manufacturerM-bM-^@M-^Ys instructions. Aliquots of Cy5-labeled and Cy3-labeled cRNA (10 ng each) were used for hybridization in a rice 44K oligo-DNA microarray.

Project description:affy_meloidogyne_rice - affy_meloidogyne_rice - Plant-parasitic nematodes cause profound economic losses to global agriculture with the obligate sedentary endoparasitic varieties; amongst them the cyst and Root Knot Nematode (RKN) species are the most damaging. Meloidogyne graminicola is a RKN mainly found in the monocotyledous plants. In the compatible interaction with Oryza sativa, M. graminicola induces the characteristic formation of hook-like galls resulting from the redifferentiation of root cells into multinucleate giant cells. In order to understand the global transcriptome changes occurring during infection, several recent microarray studies on root knots have demonstrated complex changes in host plant gene expression in response to infection. However, to our knowledge, all these transcriptome studies were performed on dicotyledous plants. A histological study enabled us to observe hyperplasia and hypertrophy of the surrounding cells leading to the formation of hook-like galls. We also investigated the plant response to M. graminicola by carrying out a global analysis of gene expression during gall formation in rice, using giant cell-enriched root tissues at an early stage (2dpi) and a latter stage (4dpi) of gall development.-Oryza sativa (var. Nipponbare) seedlings were grown on 6 cm3 SAP substrate completed with diluted Hoaglands solution (Reversat et al., 1999). Culture units were placed in a growth chamber illuminated with fluorescent tubes 9/24 h and maintained at 23°C for 5 days before being inoculated with a 100 J2-stage juveniles M. graminicola. One day after inoculation (dai), the rice seedlings were immersed in de-ionised water to remove all J2s that had not penetrated the roots and allowing synchronization of the infection. Each seedling was transferred to a hydroponic mini chamber (Reversat et al., 2004). Sampling was performed at 2 and 4 dai and each of them contained galls from 70 infected plants, they were then hand-dissected, frozen in liquid-nitrogen and stored at -80°C. As reference samples, uninfected meristematic root fragments were dissected from seedlings grown under the same conditions. Each sample was replicated 3 times. Keywords: normal vs disease comparison,time course 9 arrays - rice

Project description:affy_meloidogyne_rice - affy_meloidogyne_rice - Plant-parasitic nematodes cause profound economic losses to global agriculture with the obligate sedentary endoparasitic varieties; amongst them the cyst and Root Knot Nematode (RKN) species are the most damaging. Meloidogyne graminicola is a RKN mainly found in the monocotyledous plants. In the compatible interaction with Oryza sativa, M. graminicola induces the characteristic formation of hook-like galls resulting from the redifferentiation of root cells into multinucleate giant cells. In order to understand the global transcriptome changes occurring during infection, several recent microarray studies on root knots have demonstrated complex changes in host plant gene expression in response to infection. However, to our knowledge, all these transcriptome studies were performed on dicotyledous plants. A histological study enabled us to observe hyperplasia and hypertrophy of the surrounding cells leading to the formation of hook-like galls. We also investigated the plant response to M. graminicola by carrying out a global analysis of gene expression during gall formation in rice, using giant cell-enriched root tissues at an early stage (2dpi) and a latter stage (4dpi) of gall development.-Oryza sativa (var. Nipponbare) seedlings were grown on 6 cm3 SAP substrate completed with diluted Hoaglands solution (Reversat et al., 1999). Culture units were placed in a growth chamber illuminated with fluorescent tubes 9/24 h and maintained at 23°C for 5 days before being inoculated with a 100 J2-stage juveniles M. graminicola. One day after inoculation (dai), the rice seedlings were immersed in de-ionised water to remove all J2s that had not penetrated the roots and allowing synchronization of the infection. Each seedling was transferred to a hydroponic mini chamber (Reversat et al., 2004). Sampling was performed at 2 and 4 dai and each of them contained galls from 70 infected plants, they were then hand-dissected, frozen in liquid-nitrogen and stored at -80°C. As reference samples, uninfected meristematic root fragments were dissected from seedlings grown under the same conditions. Each sample was replicated 3 times. Keywords: normal vs disease comparison,time course

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