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Gene Expression in Response to excess Copper Stress in Rice Leaves

ABSTRACT: Gene expression in response to Cu stress in rice leaves was quantified using DNA microarray (Agilent 22K Rice Oligo Microarray) and real-time PCR technology. Rice plants were grown in hydroponic solutions containing 0.3 (control), 10, 45 or 130 µM of CuCl2, and Cu accumulation and photosynthesis inhibition were observed in leaves within 1 day of the start of treatment. Microarray analysis flagged 305 Cu-responsive genes, and their expression profile showed that a large proportion of general and defense stress response genes are up-regulated under excess Cu conditions, whereas photosynthesis and transport-related genes are down-regulated. The Cu sensitivity of each Cu-responsive gene was estimated by the median effective concentration value (EC50) and the range of fold-changes (F) under the highest (130 µM) Cu conditions (|log2F|130). Defense-related genes involved in phytoalexin and lignin biosynthesis were the most sensitive to Cu. Our results indicate that plant management of abiotic and pathogen stresses has overlapping components, possibly including signal transduction. Keywords: dose response, stress response

ORGANISM(S): Oryza sativa Oryza sativa Japonica Group

PROVIDER: GSE11021 | GEO | 2008/04/30

SECONDARY ACCESSION(S): PRJNA107115

REPOSITORIES: GEO

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Project description:Background: MicroRNAs (miRNAs) are a class of single-stranded non-coding small RNAs (sRNAs) that are 20-24 nucleotides (nt) in length. Extensive studies have indicated that miRNAs play important roles in plant growth, development, and stress responses. With more copper (Cu) and copper-containing compounds used as bactericides and fungicides in viticulture, Cu stress has become one of the serious environmental problems that affect plant growth and development. In order to uncover the hidden response mechanisms of Cu stress, many Cu-responsive miRNAs have been detected in several plant species. However, there have been few reports about the grapevine miRNAs in response to Cu. Results: Here, two small RNA libraries were constructed from Cu-treated and water-treated (control) leaves of 'Summer Black' grapevine. Following high-throughput sequencing and filtering, 158 known vvi-miRNAs and 98 novel vvi-miRNAs were identified in the two libraries. Among these, 24 could only be detected in the treatment, and 63 were only detected in the control. Additionally, 100 known vvi-miRNAs were found to be clearly responsive to Cu, among which 96 were down-regulated and four were up-regulated; 47 novel vvi-miRNAs were found to be clearly responsive to Cu, among which 35 were down-regulated and 12 were up-regulated. Subsequently, expression patterns of a set of Cu-responsive vvi-miRNAs were validated by quantitative real-time PCR (qRT-PCR). There existed some consistency in expression levels of Cu-responsive vvi-miRNAs between high-throughput sequencing and qRT-PCR assays. In addition, 92 putative targets for 79 known vvi-miRNAs and 51 putative targets for 22 novel vvi-miRNAs were predicted, and most of the targets are involved in multiple biological processes including transcriptional regulation and response to biotic and abiotic stresses. Conclusions: In this study, 147 Cu-responsive vvi-miRNAs were identified using high-throughput sequencing, and their target genes were predicted, which will be helpful to understanding the molecular mechanisms of miRNAs in response to Cu stress. Furthermore, this work can also provide a foundation for further study of the networks of miRNAs involved in grapevine plant growth and breeding some Cu-tolerant grapevine cultivars. Mixed 'Summer Black' grapevine young leaves (2 weeks old), large leaves (5 weeks old), and old leaves (9 week old) in randomly-selected plants from both the Cu-treated and control groups were collected for high-throughput sequencing. Subsequently, we carried out the analysis of Solexa sequencing data, and performed the research of regulatory modes of grapevine miRNAs on their target genes during Cu stress.

Project description:In the summer of 2012, one year after the 3.11 accident at Fukushima Daiichi nuclear power plant following the Great Tohoku Earthquake, a project was initiated to examine the effects of low-level gamma radiation on rice plants. The site of the experiment was the highly contaminated Iitate village in Fukushima prefecture of Japan. The basic experimental strategy was to expose healthy rice seedlings to continuous low-dose gamma radiation and examine the morphological and molecular genetic changes therien. Selected gene expression profiles of internal control, DNA replication/repair, oxidative stress, photosynthesis, and defense/stress functions were examined by semi-quantitative RT-PCR. Results revealed that low-level gamma radiation affects the expression of numerous genes, in particular showing the early (6 h) induction in DNA repair/damage-related genes and the late (72 h) induction of a previously described marker gene for defense/stress responses. Based on these results, which confirmed our data from preliminary experiments using detached rice leaves for radiation exposure, we proceeded for DNA microarray analysis. Using the established dye-swap approach, we analyzed the differentially expressed genes at 6 and 72 h time points using a whole rice genome 4 x 44 K custom chip. Obtained results showed that exposure to low-level gamma radiation differentially regulated 4481 (induced) and 3740 (suppressed) and 2291 (induced) and 1474 (suppressed) rice leaf genes at 6 and 72 h post-exposure, respectively, by at least two-fold changes. MapMan bioinformatics tool was also used to produce diagrams of the potential pathways, based on the input gene expression data of highly changed genes, operating downstream of the gamma radiation perception by rice plant.Inventory of a large number of gamma radiation-responsive genes in leaves provide new information and increased knowledge on novel regulatory processes in rice. The highly contaminated Iitate Farm (ITF), which is located 31 Km from the damaged nuclear power plant and having a background radiation level over 100 times (~ 5 microSv/h) than normal, was the designated place for the re-examination of low-level gamma radiation experiments using rice as a model system. As our group had a decade of experience and data on the effects of gamma radiation on leaf segments, the experimental was designed in such a way so as to expose whole rice plants to gamma radiation being emitted from the contaminated ground and examine the morphological and molecular genetic changes in the leaves under a dose-dependent manner.

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Gene Expression in Response to excess Copper Stress in Rice Leaves

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