Project description:Background: Single-cell reconstruction of gene regulatory programs provides an important tool to understand the cellular phenotypic variation in complex tissues and their response to endogenous and environmental stimuli. While the single-cell transcriptomes of several plant organs have been elucidated, the underlying chromatin landscapes remain largely unknown. Results: To comprehensively delineate chromatin accessibility during root development of an important crop, we applied single-cell ATAC-seq to 46,758 cells from rice root tips under normal and heat stress conditions. Our data revealed cell-type-specific accessibility variance across most of the major cell types and allowed us to identify sets of transcription factors which associate with accessible chromatin regions (ACRs). Using root hair differentiation as a model, we demonstrate that chromatin dynamics and gene expression dynamics during cell type differentiation correlate in pseudotime analyses. In addition to developmental trajectories, we describe chromatin responses to heat, and identify cell type specific accessibility changes to this key environmental stimulus. Conclusions: Our work provides a framework for the integrative analysis of regulatory dynamics in an important plant organ at single-cell resolution.
Project description:Background: Single-cell reconstruction of gene regulatory programs provides an important tool to understand the cellular phenotypic variation in complex tissues and their response to endogenous and environmental stimuli. While the single-cell transcriptomes of several plant organs have been elucidated, the underlying chromatin landscapes remain largely unknown. Results: To comprehensively delineate chromatin accessibility during root development of an important crop, we applied single-cell ATAC-seq to 46,758 cells from rice root tips under normal and heat stress conditions. Our data revealed cell-type-specific accessibility variance across most of the major cell types and allowed us to identify sets of transcription factors which associate with accessible chromatin regions (ACRs). Using root hair differentiation as a model, we demonstrate that chromatin dynamics and gene expression dynamics during cell type differentiation correlate in pseudotime analyses. In addition to developmental trajectories, we describe chromatin responses to heat, and identify cell type specific accessibility changes to this key environmental stimulus. Conclusions: Our work provides a framework for the integrative analysis of regulatory dynamics in an important plant organ at single-cell resolution.
Project description:The aim of this study was to determine the changes in gene expression of rice root tips when they came in to contact with a hard layer (60% wax layer). Three categories of root tips were sampled; tips before the hard layer, tips that had come into contact with the hard layer and root tips which had buckled after coming into contact with the hard layer. Two genotypes (Azucena and Bala) that vary in there ability to penetrate a hard layer were selected for a genotype comparison of gene expression at the hard layer. Keywords: Genotype comparison, root impedance response
Project description:There are two main types of root systems in flowering plants, which are taproot systems in dicot and fibrous root systems in monocot. The cellular and molecular mechanism involved in root development are mainly from the study of dicot model Arabidopsis thaliana. However, mechanisms of root development and their conservation and divergence in monocot, which including the major crops, remain largely elusive. Here we profile the transcriptomes of more than 20,000 single cells in the root tips of two rice cultivars, Nipponbare (Nip; Japonica) and 93-11 (Indica). Single-cell analysis coupled with in situ hybridization identify the cell type-specific marker genes and annotate all the clusters. Comparison of single-cell transcriptome and analysis of mark gene expression suggest well-conserved molecular landscape between rice Nip and 93-11. Moreover, our analysis suggests specific functions gene expression patterns for each cell type cluster, including the hormone genes. Comparison to Arabidopsis single-cell RNA-sequencing dataset reveals extensive differences between Arabidopsis and rice cell types, and species-specific features emphasize the importance of directly studying rice root. Our study reveals transcriptome landscape of major cell types of rice root in singe-cell resolution and provides molecular insight of the cell type morphology of cell type evolution in plants.
Project description:There are two main types of root systems in flowering plants, which are taproot systems in dicot and fibrous root systems in monocot. The cellular and molecular mechanism involved in root development are mainly from the study of dicot model Arabidopsis thaliana. However, mechanisms of root development and their conservation and divergence in monocot, which including the major crops, remain largely elusive. Here we profile the transcriptomes of more than 20,000 single cells in the root tips of two rice cultivars, Nipponbare (Nip; Japonica) and 93-11 (Indica). Single-cell analysis coupled with in situ hybridization identify the cell type-specific marker genes and annotate all the clusters. Comparison of single-cell transcriptome and analysis of mark gene expression suggest well-conserved molecular landscape between rice Nip and 93-11. Moreover, our analysis suggests specific functions gene expression patterns for each cell type cluster, including the hormone genes. Comparison to Arabidopsis single-cell RNA-sequencing dataset reveals extensive differences between Arabidopsis and rice cell types, and species-specific features emphasize the importance of directly studying rice root. Our study reveals transcriptome landscape of major cell types of rice root in singe-cell resolution and provides molecular insight of the cell type morphology of cell type evolution in plants.
Project description:The aim of this study was to determine the changes in gene expression of rice root tips when they came in to contact with a hard layer (60% wax layer). Three categories of root tips were sampled; tips before the hard layer, tips that had come into contact with the hard layer and root tips which had buckled after coming into contact with the hard layer. Two genotypes (Azucena and Bala) that vary in there ability to penetrate a hard layer were selected for a genotype comparison of gene expression at the hard layer. Experiment Overall Design: A chamber with the internal dimensions of 10 x 5 x 25cm consisting of a glass back, Perspex front and aluminium spacers with an open bottom and top was set at an angle of 15o in a large sand filled tray and filled up to 19.5 cm with dry sand. The sand was watered with nutrient solution, the sand was levelled and then a 5mm thick 60% wax layer (prepared using a ratio of 3:2 (w/w) of pastillated paraffin wax / white soft wax) was poured on the sand. Once the wax layer had set, two small holes were placed at the back of the wax layer to allow water drainage and water exchange via capillary action. The chamber was then filled up with more dry sand, and then watered using nutrient solution. Nutrient solution was then added to the large tray which the chamber had been placed; this was regularly topped up and allowed the watering of the chamber by capillary action. Light was eliminated from the chambers using white (exterior face)/black (interior face) plastic sheeting. Experiment Overall Design: Azucena and Bala seeds were surface sterilized with 1% (v/w) sodium hypochlorate for 5 minutes, then rinsed thoroughly three times with water and then germinated on moist tissue paper for 48 hours at 37oC. A single germinated seed was then sown 1 cm below the surface of the sand in each chamber. Experiment Overall Design: The plants were grown in a controlled environment room with a 12 hour day and night, with a day temperature of 30oC and a night temperature of 24oC with 300 µmol m-2 s-1 PAR. After 24 days the chamber was dismantled and the root tips of 5 mm length were harvested from Azucena plants for subsequent RNA extractions from the three categories as follows; a) roots which were between 5-10 mm above the wax layer; b) roots at the wax layer; c) roots which had buckled at the wax layer and grown 7-10 mm after buckling. From Bala plants, only root tips at the layer were harvested. Experiment Overall Design: Each condition was indsependently replicated 3 times.