Project description:Primary cell wall is an essential cell structure for plant playing major roles in plant growth, differentiation, and stress responses. Here we demonstrate that a group of AP2-ERF transcription factor regulates primary cell wall formation and can induce massive accumulation of it in empty fiber cell of the nst1-1 nst3-1 mutant lacking secondary cell wall in Arabidopsis. The transgenic plants expressing one of the AP2-ERF transcription factors fused with VP16 transcriptional activation domain under the control of NST3 promoter in the nst1-1 nst3-1 mutant showed similar level of cell wall contents with wild type by the massive accumulation of cell wall which lacks lignin and xylan. The transgenic plants showed 70% higher saccharification efficiency than wild type. Gene expression analysis using microarray revealed that genes related to primary cell wall were highly upregulated in the transgenic plant. Moreover, chimeric-activator of the AP2-ERF transcription factor accelerated cell wall regeneration of mesophyll protoplast of Arabidopsis while the chimeric-repressor retarded it. These data suggest that the group of AP2-ERF transcription factor is key regulator of the primary cell wall formation in plant and could be employed to produce massive cell wall with readily extractable feature.
Project description:In this study, the genes that encode AP2/ERF transcription factors, namely OpERF1 to OpERF5, were isolated from HR of O. pumila. Phylogenetic analysis of AP2/ERF protein sequences suggested the close evolutionary relationship of OpERF1 with stress-responsive ERF factors in Arabidopsis and of OpERF2 with ERF factors reported to regulate alkaloid production, such as ORCA3 in Catharanthus roseus, NIC2-locus ERFs in tobacco, and JRE4 in tomato. We generated the HR lines of O. pumila, ERF1i and ERF2i, in which the expression of OpERF1 and OpERF2, respectively, was suppressed using RNA interference technique. The transcriptome and metabolome of these suppressed HR were analyzed for functional characterization of OpERF1 and OpERF2.
Project description:Plant responses to drought stress require the regulation of transcriptional networks via drought responsive transcription factors, which mediate a range of morphological and physiological changes. AP2/ERF transcription factors are known to act as key regulators of drought resistance transcriptional networks; however, little is known about the associated molecular mechanisms that give rise to specific morphological and physiological adaptations. In this study, we functionally characterized the rice (Oryza sativa) drought responsive AP2/ERF transcription factor, OsERF71, which is predominantly expressed in the root meristem, pericycle, and endodermis. Overexpression of OsERF71 either throughout the entire plant or specifically in roots, resulted in a drought resistance phenotype at the vegetative growth stage, indicating that overexpression in roots was sufficient to confer drought resistance. The root specific overexpression was more effective in conferring drought resistance at the reproductive stage, such that grain yield was increased by 23-42% over wild type plants or whole-body overexpressing transgenic lines under drought conditions. OsERF71 overexpression in roots elevated the expression levels of genes related to cell wall loosening and lignin biosynthetic genes, which correlated with changes in root structure, the formation of enlarged aerenchyma and high lignification levels. Furthermore, OsERF71 was found to directly bind to the promoter of OsCCR1, a key gene in lignin biosynthesis. These results indicate that the OsERF71-mediated drought resistance pathway recruits factors involved in cell wall modification to enable root morphological adaptations, thereby providing a mechanism for enhancing drought resistance.
Project description:The AP2/ERF domain transcription factor ABSCISIC ACID INSENSITIVE4 (ABI4) modulates diverse developmental and physiological processes by integrating multiple environmental factors and phytohormone signals in plants. To further investigate the molecular mechanism of ABI4 in plant development, we examined the global gene expression in the WT and abi4-1 plants using RNA sequencing.
Project description:A method was developed to isolate RNA from 1 dpa fiber. ESTs derived from this and other cotton mRNAs were sequenced and assembled into contigs. Contigs composed of EST unique to libraries of interest and unique singletons were represented on a microarray. Microarrays were hybridized with labed nucleic acids derived from 10 dpa fiber and 1 dpa fiber to identify genes differentially regulated during fiber initiation and fiber elongation. Genes with known expression in fiber were included to validate the microarray. Analysis of the gene ontology (GO) of differentially expressed genes suported previously reported aspects of fiber initiation such as cell wall remodeling. Transcription factors upregulated in fiber initials and elongating fiber were identified Keywords: cell type comparison
Project description:To gain novel insights into the molecular mechanisms of fiber secondary cell wall development, fiber transcriptomes of the immature fiber mutant (im) with defective secondary cell wall development and its near-isogenic line, TM-1 (wild-type) were compared using cDNA microarray technology. The expression profiling was performed at 5 developmental time points: 13, 16, 19, 22, and 25dpa. Secondary cell wall development related genes were identified by differentially expressed gene analysis. And these genes could be used as potential candidate genes for manipulation to improve fiber quality.
Project description:In order to study gene expression at the genomic level during elongation and secondary cell wall synthesis of upland cotton fiber, oligonucleotide microarrays were employed. RNA was isolated from fibers in 7 different time points beginning prior to peak fiber expansion, continuing through termination of fiber expansion and ending at peak cellulose synthesis (5, 8, 10, 14, 17, 21, and 24dpa). The arrays contained ~25,000 oligonucleotides representing ~12,200 genes designed from a fiber EST database during peak cell expansion. Dynamic changes in gene expression were analyzed in a developmental context to identify stage-specific biological processes and pathways likely to be crucial to cell polar elongation or cellulose biosynthesis and secondary cell wall biogenesis. Genes with significant changes in expression relative to any preceding time point were identified (moderated t-statistics, adjusted p-value <0.05) for each developmental time point with an expected false discovery rate for multiple testing <5% A bi-directional double-loop experimental design was adopted for the microarray analysis (Kerr and Churchill, 2001; Glonek, 2004) to analyze all possible significant changes in gene expression between any two developmental time points,. The double loop design guarantees that the two time points before and after each individual time point will have direct comparisons with multiple paths available to compare any two points. Self-hybridization control experiments between independent RNA isolations for each developmental stage demonstrated a high degree of reproducibility