Project description:The cotyledons of etiolated seedlings from terrestrial flowering plants must emerge from the soil surface, while roots must penetrate the soil to ensure plant survival. We show here that the soil emergence related transcription factor PHYTOCHROME-INTERACTING FACTOR 3 (PIF3) regulates root penetration via transducing external signals perceived by the receptor kinase FERONIA (FER) in Arabidopsis thaliana. The loss of FER function in the fer-4 mutant resulted in a severe defect in root penetration into hard soil or medium. Single-cell RNA-seq profiling of roots revealed a distinct cell clustering pattern, especially for root cap cells, and revealed PIF3 as a putative FER-regulated transcription factor. Biochemical, imaging, and genetic experiments confirmed that PIF3 is required for root soil penetration. Moreover, FER interacted with and stabilized PIF3, which then modulated the expression of mechanosensitive ion channels and the sloughing of outer cells in the root cap. We propose a novel mechanism of soil penetration by plant roots.
Project description:Plant roots located in the upper soil layers are prone to experience high temperatures. To gain insight into the effect of high temperature on root development and functioning, we exposed five-day-old Arabidopsis thaliana seedlings grown on agar plates to 30 °C for 48 hours, and compared the gene expression profile in the root tip with that from seedlings that remained at 22 °C.
Project description:Bioenergy sorghum’s large and deep nodal root system and associated microbiome enables uptake of water and nutrients from and deposition of soil organic carbon into soil profiles, key contributors to the crop’s resilience and sustainability. The goal of this study was to increase our understanding of bioenergy sorghum nodal root bud development. Sorghum nodal root bud initiation was first observed on the stem node of the 7th phytomer below the shoot apex. Buds were initiated near the upper end of the stem node pulvinus on the side of the stem opposite the tiller bud, then additional buds were added over the next 6-8 days forming a ring of 10-15 nascent nodal root buds around the stem. Later in plant development, a second ring of nodal root buds began forming on the 17th stem node immediately above the first ring of buds. Overall, nodal root bud development can take ~40 days from initiation to onset of nodal root outgrowth. Nodal root buds were initiated in close association with vascular bundles in the rind of the pulvinus. Stem tissue forming nascent nodal root buds expressed sorghum homologs of genes associated with root initiation (WOX4), auxin transport (LAX2, PIN4), meristem activation (NGAL2), and genes involved in cell proliferation. Expression of WOX11 and WOX5, genes involved in root stem niche formation, increased early in nodal root bud development followed by genes encoding PLTs, LBDs (LBD29), LRP1, SMB, RGF1 and root cap LEAs later in development. A nodal root bud gene regulatory network module expressed during nodal root bud initiation predicted connections linking PFA5, SPL9 and WOX4 to genes involved in hormone signaling, meristem activation, and cell proliferation. A network module expressed later in development predicted connections among SOMBRERO, a gene involved in root cap formation, and GATA19, BBM, LBD29 and RITF1/RGF1 signaling. Overall, this study provides a detailed description of bioenergy sorghum nodal root bud development and transcriptome information useful for understanding the regulation of sorghum nodal root bud formation and development.
Project description:The plant hormone gibberellin (GA) represents an important regulator of growth and development. Early transcriptional events controlled by GA are not well characterised. Previous microarray studies have identified genes responsive to GA treatment in the whole seedling. The whole seedling represents many tissues where subtle effects of GA treatment in specific tissues may be masked. When treated with GA, an effect on the growth rate of roots was observed. More specifically, the shorter root of a GA-deficient plant can be rescued to wild-type length by the application of GA. This experiment was designed to identify GA-regulated genes in the root tips of Arabidopsis. The use of a GA-deficient mutant provides a greater potential to identify genes responding to GA treatment. Root tips are ideally suited for the quick uptake of the hormone treatment. There will be two biological replicates which will each consist of a control treatment at 0 minutes and 2 hours, as well as the experimental GA-treated 2 hour time point. This system provides an opportunity to compare gene expression between treated and non-treated root tips and allow the identification of early GA-responsive genes.
Project description:As an important adaptation to drought stress, several agronomic species, such as soybean and maize, can maintain the primary root substantial elongation rates at low water potentials, whereas shoot growth stops completely. In soybean, kinematic characterization of the spatial patterns of cell expansion within the root elongation zone showed that at low water potentials, elongation rates were preferentially maintained toward the root apex but were progressively inhibited at more basal locations, resulting in a shortened growth zone. To explore the molecular mechanism of root elongation in response to water stress, we set out to examine the expression of soybean genes in different root regions after 5 hours (5h) and 48 hours (48h) water stress treatment using the Affymetrix Soybean GeneChip containing 37,500 G. max probe sets.
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 Arabidopsis basic leucine zipper transcription factor bZIP29 of the bZIP group I TF family, expressed mainly in proliferative tissues, is functionally characterized in this study. In roots, bZIP29 is highly expressed in the quiescent centre and the columella cells of the root apical meristem. Mutant analyses demonstrate that bZIP29 regulates root meristem cell number and root gravitropic responses. RNA-seq transcriptome profiling of the root meristem shows that bZIP29 target genes are linked to cell wall organization, and that gene regulatory networks controlling proper root meristem organization are intensively rewired upon its perturbation.
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.