Project description:We performed an analysis of transcriptomic responses to auxin within four distinct tissues of the Arabidopsis thaliana root. This high-resolution dataset shows how different cell types are predisposed to react to auxin with discrete transcriptional responses. The sensitivity provided by the analysis lies in the ability to detect cell-type specific responses diluted in organ-level analyses. This dataset provides a novel resource to examine how auxin, a widespread signal in plant development, influences differentiation and patterning in the plant through tissue-specific transcriptional regulation.
Project description:We performed an analysis of transcriptomic responses to auxin within four distinct tissues of the Arabidopsis thaliana root. This high-resolution dataset shows how different cell types are predisposed to react to auxin with discrete transcriptional responses. The sensitivity provided by the analysis lies in the ability to detect cell-type specific responses diluted in organ-level analyses. This dataset provides a novel resource to examine how auxin, a widespread signal in plant development, influences differentiation and patterning in the plant through tissue-specific transcriptional regulation. To analyze the effect of auxin in separate spatial domains of the root, early transcriptional changes in response to auxin treatment were assayed by means of fluorescence activated cell sorting (FACS) and microarray analysis in four tissues of the Arabidopsis root (wild type Col-0). The samples covered inner and outer as well as proximal and distal cell populations; including the stele (reporter line pWOL::GFP), xylem-pole (xp) pericycle (enhancer trap line E3754), epidermis/lateral root cap (reporter line pWER::GFP) and columella (enhancer trap line PET111). One-week-old seedlings of the individual lines were treated with auxin (two hours, 5µM indole-3-acetic acid [IAA]) or mock treated, after which roots were harvested and cells were dissociated by cell wall digestion (1 hour; including 5uM IAA) . GFP-positive cells were sorted and used for microarray transcriptome analysis (as in Bargmann and Birnbaum, Plant Phys. 2010). For comparison, transcriptional responses to auxin were also assayed in intact (undigested) roots.
Project description:This study evaluates the effects of exogenous auxin on the Arabidopsis thaliana root proteome at 8, 12, and 24 hours post-treatment.
Project description:We report differences in the transcriptional responses of the root and the shoot to either auxin or ABA in comparison to mock treatment in dark-grown Arabidopsis thaliana seedlings. By examining the auxin responsiveness in the shoot or the root of a dark-growh ABA biosynthesis mutant, we found that auxin relies on intact ABA biosynthesis in order to regulate aspects of transriptional output.
Project description:TRH1, also classified as KUP4, belongs in the family of plant HAK/KUP/KT (High-Affinity K+/ K+ UPtake/ K+ Transporter) transporters, homologous to the bacterial KUP and fungal HAK transporters, which most likely as K+/H+ exchangers function as electrochemical potential-driven transporters. Arabidopsis contains 13 genes, classified into five major clades (Clades I-V). Members of Clade II, including TRH1, are associated with developmental processes. Targeted expression experiments demonstrated that K+ transporter TRH1 is a coupler of two auxin-mediated developmental processes that determine Root System Architecture, root hair morphogenesis and root gravitropism. Targeting TRH1 expression in central cylinder cells that coincide with the acropetal route of auxin transport, rescued trh1 root agravitropism, whereas positional TRH1 expression in peripheral cell layers that define the basipetal route of auxin transport, restored trh1 root hair defects. To dissect the two auxin-mediated developmental responses, a transcriptome analysis was performed identifying the differentially expressed genes involved in either root bending or root hair development.
Project description:The acquisition of water and nutrients by plant roots is a fundamental aspect of agriculture and strongly depends on root architecture. Root branching and expansion of the root system is achieved through the development of lateral roots and is to a large extent controlled by the plant hormone auxin. However, the pleiotropic effects of auxin or auxin-like molecules on root systems complicate the study of lateral root development. Here we describe a small-molecule screen in Arabidopsis thaliana that identified naxillin as what is to our knowledge the first non-auxin-like molecule that promotes root branching. By using naxillin as a chemical tool, we identified a new function for root cap-specific conversion of the auxin precursor indole-3-butyric acid into the active auxin indole-3-acetic acid and uncovered the involvement of the root cap in root branching. Delivery of an auxin precursor in peripheral tissues such as the root cap might represent an important mechanism shaping root architecture. To further explore the specificity of naxillin for lateral root development, we compared the early effects of naxillin at the transcriptome level with NAA (1-Naphthaleneacetic acid) in roots of 3-day-old seedlings after 2-h and 6-h treatment.
Project description:The acquisition of water and nutrients by plant roots is a fundamental aspect of agriculture and strongly depends on root architecture. Root branching and expansion of the root system is achieved through the development of lateral roots and is to a large extent controlled by the plant hormone auxin. However, the pleiotropic effects of auxin or auxin-like molecules on root systems complicate the study of lateral root development. Here we describe a small-molecule screen in Arabidopsis thaliana that identified naxillin as what is to our knowledge the first non-auxin-like molecule that promotes root branching. By using naxillin as a chemical tool, we identified a new function for root cap-specific conversion of the auxin precursor indole-3-butyric acid into the active auxin indole-3-acetic acid and uncovered the involvement of the root cap in root branching. Delivery of an auxin precursor in peripheral tissues such as the root cap might represent an important mechanism shaping root architecture. To further explore the specificity of naxillin for lateral root development, we compared the early effects of naxillin at the transcriptome level with NAA (1-Naphthaleneacetic acid) in roots of 3-day-old seedlings after 2-h and 6-h treatment. Arabidopsis thaliana (L). Heynh., Col-0 seeds were germinated vertically on solid medium derived from standard MS medium supplemented with 10 μM NPA (1-N-Naphthylphthalamic acid). Three days after germination, plants were transferred to 10 μM NAA (1-Naphthaleneacetic acid) or 50 μM naxillin for 2 and 6 hours. Plants were sampled before (Roots at T0, NPA) or after treatment (Roots at T1 and T2). RNA isolation was performed on 500 root sections (only root without meristems) for each sample. All sampling points were performed in three independent experiments.
Project description:Canonical auxin signalling starts with auxin binding to the receptor complex, followed by modulation of gene transcription and protein abundance (Tan et al., 2007; Chapman and Estelle, 2009; Slade et al., 2017). However, recent studies also showed an alternative mechanism in roots involving intra-cellular auxin perception, but not transcriptional reprogramming (Fendrych et al., 2018). Despite knowledge on effects of auxin on Arabidopsis root growth at the protein and phosphorylation level is increasing (Zhang et al., 2013; Mattei et al., 2013; Slade et al., 2017), it still remains incomplete. To address this gap in our knowledge, we explored the impact of auxin on the root tip proteome and phosphoproteome.
Project description:Genome wide transcriptome profiling of pericycle cells from roots exposed to auxin, cytokinin and both hormones simultaneously. Lateral root organogenesis in Arabidopsis is governed by a complex network of hormonal regulations. Plant hormones auxin and cytokinin were demonstrated to be the key regulators of this lateral root organogenesis and their mode of interaction is antagonistic. The aim of the project is to understand the role of the auxin - cytokinin signalling pathways in lateral root organogenesis.
Project description:C-terminally encoded peptides (CEPs) are peptide hormones that function as mobile signals coordinating crucial developmental programs in plants. Previous studies have revealed that CEPs exert negative regulation on root development through interaction with CEP receptors (CEPRs), CEPR DOWNSTREAMs (CEPDs), the cytokinin receptor ARABIDOPSIS HISTIDINE KINASE (AHKs) and the transcriptional repressor Auxin/Indole-3-Acetic Acid (AUX/IAA). However, the precise molecular mechanisms underlying CEPs-mediated regulation of root development via auxin and cytokinin signaling pathways still necessitate further detailed investigation. In this study, we examined prior research and elucidated the underlying molecular mechanisms. The results showed that both synthetic AtCEPs and overexpression of AtCEP5 markedly supressed primary root elongation and lateral root (LR) formation in Arabidopsis. Molecular biology and genetics elucidated how CEPs inhibit root growth by suppressing auxin signaling while promoting cytokinin signaling. In summary, this study elucidated the inhibitory effects of AtCEPs on Arabidopsis root growth and provided insights into their potential molecular mechanisms, thus enhancing our comprehension of CEP-mediated regulation of plant growth and development.