Project description:The plant hormone cytokinin regulates diverse aspects of plant growth and development, likely through context-dependent transcriptional regulation that relies on a dynamic interplay between regulatory proteins and chromatin. We employed the Assay for Transposase Accessible Chromatin (ATAC-Seq) to profile changes in the chromatin landscape of Arabidopsis roots and shoots in response to cytokinin. Our results reveal differentially accessible chromatin regions indicative of dynamic regulation in response to cytokinin. These changes in chromatin occur preferentially upstream of genes whose expression changes in response to cytokinin and largely overlap with binding sites for the type-B ARRs, transcription factors that mediate the primary response to cytokinin. Further, the type-B ARRs were found to be necessary for the changes in chromatin state in response to cytokinin. Lastly, we find context-dependent responses by comparing root and shoot profiles. These datasets provide new insights into the transcriptional regulatory mechanisms involved in the cytokinin response and how cytokinin mediates its pleiotropic effects.
Project description:This study aims to identify genes which are differentially expressed in root and/or shoot material in response to exogenous cytokinin. Roots and shoots were collected separately.
Project description:In plant tissue culture, callus forms from detached explants in response to a high-auxin-to-low-cytokinin ratio on callus-inducing medium. Callus is a group of pluripotent cells because it can regenerate either roots or shoots in response to a low level of auxin on root-inducing medium or a high-cytokinin-to-low-auxin ratio on shoot-inducing medium, respectively1. However, our knowledge of the mechanism of pluripotency acquisition during callus formation is limited. On the basis of analyses at the single-cell level, we show that the tissue structure of Arabidopsis thaliana callus on callus-inducing medium is similar to that of the root primordium or root apical meristem, and the middle cell layer with quiescent centre-like transcriptional identity exhibits the ability to regenerate organs. In the middle cell layer, WUSCHEL-RELATED HOMEOBOX5 (WOX5) directly interacts with PLETHORA1 and 2 to promote TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS1 expression for endogenous auxin production. WOX5 also interacts with the B-type ARABIDOPSIS RESPONSE REGULATOR12 (ARR12) and represses A-type ARRs to break the negative feedback loop in cytokinin signalling. Overall, the promotion of auxin production and the enhancement of cytokinin sensitivity are both required for pluripotency acquisition in the middle cell layer of callus for organ regeneration.
Project description:In plant tissue culture, callus forms from detached explants in response to a high-auxin-to-low-cytokinin ratio on callus-inducing medium. Callus is a group of pluripotent cells because it can regenerate either roots or shoots in response to a low level of auxin on root-inducing medium or a high-cytokinin-to-low-auxin ratio on shoot-inducing medium, respectively1. However, our knowledge of the mechanism of pluripotency acquisition during callus formation is limited. On the basis of analyses at the single-cell level, we show that the tissue structure of Arabidopsis thaliana callus on callus-inducing medium is similar to that of the root primordium or root apical meristem, and the middle cell layer with quiescent centre-like transcriptional identity exhibits the ability to regenerate organs. In the middle cell layer, WUSCHEL-RELATED HOMEOBOX5 (WOX5) directly interacts with PLETHORA1 and 2 to promote TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS1 expression for endogenous auxin production. WOX5 also interacts with the B-type ARABIDOPSIS RESPONSE REGULATOR12 (ARR12) and represses A-type ARRs to break the negative feedback loop in cytokinin signalling. Overall, the promotion of auxin production and the enhancement of cytokinin sensitivity are both required for pluripotency acquisition in the middle cell layer of callus for organ regeneration.
Project description:In plant tissue culture, callus forms from detached explants in response to a high-auxin-to-low-cytokinin ratio on callus-inducing medium. Callus is a group of pluripotent cells because it can regenerate either roots or shoots in response to a low level of auxin on root-inducing medium or a high-cytokinin-to-low-auxin ratio on shoot-inducing medium, respectively1. However, our knowledge of the mechanism of pluripotency acquisition during callus formation is limited. On the basis of analyses at the single-cell level, we show that the tissue structure of Arabidopsis thaliana callus on callus-inducing medium is similar to that of the root primordium or root apical meristem, and the middle cell layer with quiescent centre-like transcriptional identity exhibits the ability to regenerate organs. In the middle cell layer, WUSCHEL-RELATED HOMEOBOX5 (WOX5) directly interacts with PLETHORA1 and 2 to promote TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS1 expression for endogenous auxin production. WOX5 also interacts with the B-type ARABIDOPSIS RESPONSE REGULATOR12 (ARR12) and represses A-type ARRs to break the negative feedback loop in cytokinin signalling. Overall, the promotion of auxin production and the enhancement of cytokinin sensitivity are both required for pluripotency acquisition in the middle cell layer of callus for organ regeneration.
Project description:Optimal plant growth is hampered by limiting amounts of the essential macronutrient phosphate in most soils. As a response, plant roots produce root hairs to capture this immobile nutrient. Although vital to high-yielding crops, this response remains poorly understood. By generating and exploiting a high spatial and temporal resolution single cell atlas of the Arabidopsis root, we show a remarkable enrichment of TMO5/LHW target genes in root hair epidermal cells. Moreover, these vascular bHLH factors are sufficient to induce a root hair formation response in the epidermal cells, similar as observed during low phosphate conditions, via the downstream cytokinin signaling. We further show that root hair formation under low phosphate conditions is almost absent when TMO5 function or cytokinin signaling is perturbed. In conclusion, cytokinin signaling links the adaptation of roots under low phosphate conditions in the epidermis to perception in vascular cells.
Project description:CURLY LEAF (CLF), the major histone methyltransferase of Polycomb Repressive Complex 2 (PRC2), modifies trimethylation of histone H3 lysine 27 (H3K27me3) and mediates dynamical chromatin repression in Arabidopsis. Here we used strand specific RNA-sequencing to profile Arabidopsis transcriptomes obtained from roots, shoots, flowers and siliques of Col-0 and clf-28 plants. Our analysis identified a large number of CLF-regulatedd transcripts in Arabidopsis. Transcriptome profiling in roots, shoots, inflorescences and siliques of WT and clf-28 plants with 3 biological replicates.
Project description:We have analyzed the effect of high temepratures in roots and shoots of Arabidopsis using a novel approach, since we cultivate the seedlings with the root system in a temeprature gradient, simulatinfg the soil.
Project description:The development of high-throughput genomic technologies has revealed that a large fraction of the genomes of eukaryotes is associated with the expression of noncoding RNAs. One class of noncoding RNA, the cis-natural antisense transcripts (cis-NATs), are particularly interesting as they are at least partially complementary to the protein-coding mRNAs. Although most studies described cis-NATs involved in the regulation of transcription, a few reports have shown recently that cis-NATs can also regulate translation of the cognate sense coding genes in plants and mammals. In order to identify novel examples of translation regulator cis-NATs in Arabidopsis thaliana, we designed a high-throughput experiment based on polysome profiling and RNA-sequencing. Expression of cis-NATs and translation efficiency of the cognate coding mRNAs were measured in roots and shoots in response to various conditions, including phosphate deficiency and treatment with phytohormones. We identified several promising candidates, and validated a few of them experimentally, in Arabidopsis thaliana transgenic lines over-expressing in trans the translation regulator candidate cis-NATs.