Project description:Vascular cambium is a secondary meristem which produces xylem (wood) inwards and phloem (bark) outwards. The activity of cambium leads to expansion in the diameters in plants, that is, secondary growth, and thus contributes to biomass increase. The regulation of cambium development is at multilevel including phytohormones and peptide-receptor kinase (CLE41/44-PXY) signalling pathways. However, only limited progress has been made on the transcriptional regulation level. To construct the transcriptional network that regulates cambium development, we performed a genome wide transcript profiling in sorted procambial and cambial cells in Arabidopsis roots. More than 500 genes were identified as cambium abundant genes via comparison against transcriptomes of other Arabidopsis root cell types. We then investigated the roles of almost all the cambial transcription factors (TFs) and some of their homologous genes during secondary growth. Many of the candidate TFs were highly expressed in cambium based on the promoter GUS fusion and in situ hybridization. An unbiased transcriptional regulatory network was constructed using transcript profiling data collected from inducible overexpression lines for selected candidate TFs and a few major nodes were identified in the network including WOX4 and KNAT1. Moreover, the severity of mutant phenotypes was predicted based on the network. Next, we used the predication as a guide and generated over 70 double mutants within the same or among different TF families to explore the genetic interactions of candidate genes. Phenotype characterization on the secondary growth of the mutants and the overexpression lines identified promoters and inhibitors of cambium activity. The phenotypic data also suggested the redundancy within and among TF families because the phenotypes could be enhanced when additional TFs were mutated. We also found that combinations of certain overexpression lines and mutants led to pronounced increase of cell proliferation or xylem differentiation and in the extreme case the formation of ectopic cambium. We herein propose that cambium development is orchestrated by a wide network at the transcriptional level, where each TF has a different contribution to cell proliferation and differentiation.
Project description:The root epidermis of Arabidopsis provides a simple and experimentally useful model for studying the molecular basis of cell fate and differentiation. The goal of this study was to define the larger gene regulatory network that governs the differentiation of the root hair and non-hair cell types of the Arabidopsis root epidermis. Transcript levels in the root epidermis of wild-type and mutant lines were assessed by purifying populations of root epidermal cells using fluorescence-based cell-sorting. Further, the role of the plant hormones auxin and ethylene on root epidermis development was assessed by defining transcript levels in the root epidermis of plants grown on media containing IAA or ACC. These microarray results were used to construct a comprehensive gene regulatory network that depicts the transcriptional control of root epidermal cell fate and differentiation in Arabidopsis.
Project description:The differentiation of specialized feeding sites in Arabidopsis root cells in response to nematode infestation involves substantial cellular reprogramming of host cells that is not well characterized at the molecular level. Expression data was generated from Arabidopsis root cells undergoing giant cell formation due to nematode infestation and from non-infested control root cells. Cells were laser captured 14 and 21 days after infestation.
Project description:In-vivo induced establishment and activity of the interfascicular cambium in Arabidopsis thaliana stems under NPA treatments. We used microarrays to detail the global programme of gene expression underlying the establishment and activity of the interfascicular cambium.
Project description:The root epidermis of Arabidopsis provides a simple and experimentally useful model for studying the molecular basis of cell fate and differentiation. The goal of this study was to define the transcript changes in the root epidermis of mutants associated with root epidermis cell specification, including mutants that lack a visible phenotypic alteration (try, egl3, myb23, and ttg2). Transcript levels were assessed by purifying populations of root epidermal cells using fluorescence-based cell-sorting with the WER::GFP transgene. These microarray results were used to compare the effects of single and double mutants on the gene regulatory network that controls root epidermal cell fate and differentiation in Arabidopsis.
Project description:In-vitro induced establishment and activity of the interfascicular cambium in Arabidopsis thaliana stems under auxin treatments. We used microarrays to detail the global programme of gene expression underlying the establishment and activity of the interfascicular cambium and identified tissue-speciffic up-regulated genes during this process.
Project description:The RETINOBLASTOMA–RELATED (RBR) is a key regulator of cell proliferation and differentiation in plants, and plays an important role in maintenance of the stem cell niche in the root. We used microarray analysis to characterize the transcriptional response of Arabidopsis thaliana root tips from rRBr mutant (7 samples) against Col-0 wild type (6 samples) after 4, 6 and 10 das.
Project description:The root epidermis of Arabidopsis provides a simple and experimentally useful model for studying the molecular basis of cell fate and differentiation. The goal of this study was to define the larger gene regulatory network that governs the differentiation of the root hair and non-hair cell types of the Arabidopsis root epidermis. Transcript levels in the root epidermis of wild-type and mutant lines were assessed by purifying populations of root epidermal cells using fluorescence-based cell-sorting. Further, the role of the plant hormones auxin and ethylene on root epidermis development was assessed by defining transcript levels in the root epidermis of plants grown on media containing IAA or ACC. These microarray results were used to construct a comprehensive gene regulatory network that depicts the transcriptional control of root epidermal cell fate and differentiation in Arabidopsis. The cells of the developing root epidermis were obtained by growing plant seedlings expressing the WER::GFP transgene under sterile conditions on MS media, cutting off root tips (including all developmental stages), protoplasting the roots, and purifying cells containing GFP using FACS. The WER::GFP transgene is expressed throughout the developing cells of the root epidermis and the lateral root cap. Three biological replicates were analyzed for each of the 25 plant lines examined in this study.