Expression Profiles In Plants Research Articles

Integration of small RNAs, degradome, and transcriptome sequencing in Populus × euramericana “Neva” provides insights into the allelopathic interference of para-hydroxybenzoic acid

Allelopathy is a hot topic of research; however, little is known regarding microRNA (miRNA) expression profiles in plants in response to allelochemicals. In this study, we combined the analyses of the transcriptome, small RNAs (sRNAs), and the degradome to identify key regulatory miRNA-targeted circuits under para-hydroxybenzoic acid (pHBA) stress. A total of 739 and 673 miRNAs were identified in leaves and roots, respectively. Of those, 214 and 148 miRNAs were significantly differentially expressed and identified as pHBA-responsive miRNAs in leaves and roots, respectively. The target genes for the pHBA-responsive miRNAs are involved in signal transduction, response to stress, and secondary metabolite pathways. Furthermore, an integrated analysis of the miRNA–target expression profiles was used to screen the 60 differentially expressed target genes from the 46 differentially expressed miRNAs in the leaves and the 51 differentially expressed target genes from the 36 differentially expressed miRNAs in roots. This integrated analysis revealed 17 and 30 pairs of miRNA targets in the leaves and roots, respectively, which had negatively correlated expression profiles. According to a real-time quantitative polymerase chain reaction (PCR) analysis, 14 miRNA–target pairs also exhibited negative correlations. Moreover, four coexpression regulatory networks were constructed based on the profiles of the differentially expressed miRNA–target pairs. These results suggest that comprehensive analyses of transcriptomes, sRNAs, and the degradome provide a useful platform for investigating the molecular mechanism underlying the pHBA-induced stress response in plants.

Global Transcriptome Analysis Reveals Acclimation-Primed Processes Involved in the Acquisition of Desiccation Tolerance in Boea hygrometrica.

Boea hygrometrica resurrection plants require a period of acclimation by slow soil-drying in order to survive a subsequent period of rapid desiccation. The molecular basis of this observation was investigated by comparing gene expression profiles under different degrees of water deprivation. Transcripts were clustered according to the expression profiles in plants that were air-dried (rapid desiccation), soil-dried (gradual desiccation), rehydrated (acclimated) and air-dried after acclimation. Although phenotypically indistinguishable, it was shown by principal component analysis that the gene expression profiles in rehydrated, acclimated plants resemble those of desiccated plants more closely than those of hydrated acclimated plants. Enrichment analysis based on gene ontology was performed to deconvolute the processes that accompanied desiccation tolerance. Transcripts associated with autophagy and α-tocopherol accumulation were found to be activated in both air-dried, acclimated plants and soil-dried non-acclimated plants. Furthermore, transcripts associated with biosynthesis of ascorbic acid, cell wall catabolism, chaperone-assisted protein folding, respiration and macromolecule catabolism were activated and maintained during soil-drying and rehydration. Based on these findings, we hypothesize that activation of these processes leads to the establishment of an optimal physiological and cellular state that enables tolerance during rapid air-drying. Our study provides a novel insight into the transcriptional regulation of critical priming responses to enable survival following rapid dehydration in B. hygrometrica.

Next-generation sequencing technologies for gene expression profiling in plants

Next-generation sequencing (NGS) provides a better approach to gene expression profiling with several advantages. The power of NGS along with novel molecular techniques and computational tools allow the researchers to perform the gene expression profiling to reveal transcriptional complexity of an organism and answering several biological questions. Although many studies for gene expression profiling related to various aspects have been performed in animal systems revealing unprecedented levels of complexity of transcriptomes, their use is still limited in plant biology. This review describes the use of NGS technologies with respect to gene expression profiling, bioinformatics challenges associated with data analysis and advances made so far in the plant biology research. We anticipate many more studies in recent future, which will surely advance our understanding of the complexity of plant genomes.

Isolation of dehydration-responsive genes in a drought tolerant common bean cultivar and expression of a group 3 late embryogenesis abundant mRNA in tolerant and susceptible bean cultivars.

Drought is one of the main constraints for common bean (Phaseolus vulgaris L.) production in Latin America. The aim of this work was to identify upregulated genes in the drought-tolerant common bean cv. Pinto Villa, grown under water-deficit conditions. Twenty-eight cDNAs representing differentially-expressed mRNAs in roots and/or leaves were isolated via suppression subtractive hybridisation. Their expression profiles in plants under intermediate and severe dehydration stress were tested. Three cDNAs corresponded to genes already described as associated to drought stress in P. vulgaris, 12 were known P. vulgaris sequences without previous association with drought response, and 13 were new P. vulgaris sequences. Analysis of the deduced proteins encoded by the cDNAs revealed putative functions in cellular protection, sugar metabolism, and protein synthesis, folding and turnover. Additionally, a new member of group 3 late embryogenesis abundant (LEA) genes (PvLEA3) was cloned and its complete sequence was obtained. Given the lack of reports comparing expression of dehydration-responsive genes in bean cultivars with different response to drought, the expression of PvLEA3 transcript in five bean cultivars from different origin was analysed. The induction of PvLEA3 was directly associated with the level of drought tolerance in the cultivars studied.

Cell Type-Specific Gene Expression Profiling in Plants by Using a Combination of Laser Microdissection and High-Throughput Technologies

Laser microdissection (LM) allows for the isolation of specific cells of interest from heterogeneous tissues under direct microscopic visualization with the assistance of a laser beam. By permitting global analyses of gene expression and metabolites in the selected cells, it is a powerful tool for understanding the biological processes in individual cell types during development or in response to various stimuli. Recently, LM technology has been successfully applied to the separation of individual plant cell types. Here, we provide an overview of applications of LM combined with high-throughput technologies including transcript analyses [microarrays, serial analysis of gene expression (SAGE) and 454-sequencing], proteomic analyses and metabolomic profiling, for cell type-specific gene expression analyses in plants.

Cell type–specific expression profiling in plants via cell sorting of protoplasts from fluorescent reporter lines

Cell type–specific expression profiling in plants via cell sorting of protoplasts from fluorescent reporter lines

Computational Identification of Novel Family Members of MicroRNA Genes in Arabidopsis thaliana and Oryza sativa

MicroRNAs (miRNAs) are a class of endogenous small RNAs that play important regulatory roles in both animals and plants, miRNA genes have been intensively studied in animals, but not in plants. In this study, we adopted a homology search approach to identify homologs of previously validated plant miRNAs in Arabidopsis thaliana and Oryza sativa. We identified 20 potential miRNA genes in Arabidopsis and 40 in O. sativa, providing a relatively complete enumeration of family members for these miRNAs in plants. In addition, a greater number of Arabidopsis miRNAs (MIR168, MIR159 and MIR172) were found to be conserved in rice. With the novel homologs, most of the miRNAs have closely related fellow miRNAs and the number of paralogs varies in the different miRNA families. Moreover, a probable functional segment highly conserved on the elongated stem of pre-miRNA fold-backs of MIR319 and MIR159 family was identified. These results support a model of variegated miRNA regulation in plants, in which miRNAs with different functional elements on their pre-miRNA fold-backs can differ in their function or regulation, and closely related miRNAs can be diverse in their specificity or competence to downregulate target genes. It appears that the sophisticated regulation of miRNAs can achieve complex biological effects through qualitative and quantitative modulation of gene expression profiles in plants.

Computational Identification of Novel Family Members of MicroRNA Genes in <italic>Arabidopsis thaliana</italic> and <italic>Oryza sativa</italic>

MicroRNAs (miRNAs) are a class of endogenous small RNAs that play important regulatory roles in both animals and plants. miRNA genes have been intensively studied in animals, but not in plants. In this study, we adopted a homology search approach to identify homologs of previously validated plant miRNAs in Arabidopsis thaliana and Oryza sativa. We identified 20 potential miRNA genes in Arabidopsis and 40 in O. sativa, providing a relatively complete enumeration of family members for these miRNAs in plants. In addition, a greater number of Arabidopsis miRNAs (MIR168, MIR159 and MIR172) were found to be conserved in rice. With the novel homologs, most of the miRNAs have closely related fellow miRNAs and the number of paralogs varies in the different miRNA families. Moreover, a probable functional segment highly conserved on the elongated stem of pre-miRNA fold-backs of MIR319 and MIR159 family was identified. These results support a model of variegated miRNA regulation in plants, in which miRNAs with different functional elements on their pre-miRNA fold-backs can differ in their function or regulation, and closely related miRNAs can be diverse in their specificity or competence to downregulate target genes. It appears that the sophisticated regulation of miRNAs can achieve complex biological effects through qualitative and quantitative modulation of gene expression profiles in plants.

ESTs, cDNA microarrays, and gene expression profiling: tools for dissecting plant physiology and development.

Gene expression profiling holds tremendous promise for dissecting the regulatory mechanisms and transcriptional networks that underlie biological processes. Here we provide details of approaches used by others and ourselves for gene expression profiling in plants with emphasis on cDNA microarrays and discussion of both experimental design and downstream analysis. We focus on methods and techniques emphasizing fabrication of cDNA microarrays, fluorescent labeling, cDNA hybridization, experimental design, and data processing. We include specific examples that demonstrate how this technology can be used to further our understanding of plant physiology and development (specifically fruit development and ripening) and for comparative genomics by comparing transcriptome activity in tomato and pepper fruit.