Project description:Stem cells are defined by their ability to self-renew and produce daughter cells that proliferate and mature. These maturing cells transition from a proliferative state to a terminal state through the process of differentiation. In the Arabidopsis thaliana root the transcription factors SCARECROW and SHORTROOT regulate specification of the bi-potent stem cell that gives rise to the cortical and endodermal progenitors. Subsequent progenitor proliferation and differentiation generates mature endodermis, marked by the Casparian Strip: a cell wall modification that prevents ion diffusion into and out of the vasculature. We identified a transcription factor, MYB36 that regulates the transition from proliferation to differentiation in the endodermis. We show that SCARECROW directly activates MYB36 expression, which in turn directly regulates essential Casparian Strip formation genes. In addition, MYB36 represses extra divisions within the endodermis. Our results demonstrate that MYB36 is a critical positive regulator of differentiation and negative regulator of cell proliferation. 12 samples analyzed: 3 biological replicates each from 1) wild type (Col-0) whole root, 2) mutant (myb36-1) whole root, 3) wild type (Col-0) sorted endodermis, 4) mutant (myb36-1) sorted endodermis
Project description:In our previous work, we found that the root exudates of sgn3 myb36 promoted the colonization of CHA0 on roots. Through LC-MS, we identified a large amount of glutamine (Gln) in the root exudates of sgn3 myb36. Therefore, we aim to use RNA-seq to uncover whether the root exudates of sgn3 myb36 and Gln have the same regulatory effects on CHA0. By conducting differential analysis with the CK (CHA0 treated with wild-type root exudates), we hope to identify the specific regulatory mechanisms of sgn3 myb36 and Gln on CHA0.
Project description:Stem cells are defined by their ability to self-renew and produce daughter cells that proliferate and mature. These maturing cells transition from a proliferative state to a terminal state through the process of differentiation. In the Arabidopsis thaliana root the transcription factors SCARECROW and SHORTROOT regulate specification of the bi-potent stem cell that gives rise to the cortical and endodermal progenitors. Subsequent progenitor proliferation and differentiation generates mature endodermis, marked by the Casparian Strip: a cell wall modification that prevents ion diffusion into and out of the vasculature. We identified a transcription factor, MYB36 that regulates the transition from proliferation to differentiation in the endodermis. We show that SCARECROW directly activates MYB36 expression, which in turn directly regulates essential Casparian Strip formation genes. In addition, MYB36 represses extra divisions within the endodermis. Our results demonstrate that MYB36 is a critical positive regulator of differentiation and negative regulator of cell proliferation.
Project description:This experiment has been annotated by TAIR (http://arabidopsis.org). In this experiment, different tissue preparations of wild type Columbia-0 Arabidopsis thaliana plants were hybridized and run on the ATH1 Affymetrix platform. Experimenter name = Chris Somerville Experimenter phone = 650-325-1521 ext203 Experimenter fax = 650-325-6857 Experimenter address = Plant Biology Experimenter address = Carnegie Institution Experimenter address = 260 Panama Street Experimenter address = Stanford Experimenter zip/postal_code = CA 94305-1297 Experimenter country = USA Keywords: organism_part_comparison_design;
Project description:In plants, apical meristems allow continuous growth along the body axis. Within the root apical meristem (RAM), a group of slowly dividing quiescent center (QC) cells is thought to limit stem cell activity to directly neighboring cells (Cowels, 1956; van den Berg et al., 1997), thus endowing them with unique properties, distinct from displaced daughters. This binary identity of the stem cells stands in apparent contradiction with the more gradual changes in cell division potential (Bennett and Scheres, 2010) and differentiation (Yamaguchi et al., 2008; 2010; Furuta et al, 2014; Geldner, 2013; Masucci et al., 1996; Dolan and Costa, 2001) that occur as cells move further away from the QC. To address this paradox and to infer molecular organization of the root meristem, we used a whole-genome approach to determine dominant transcriptional patterns along root ontogeny zones. We found that the prevalent patterns are expressed in two opposing gradients. One is characterized by genes associated with development, the other enriched in differentiation genes. We confirmed these transcript gradients, and demonstrate that these translate to gradients in protein accumulation and gradual changes in cellular properties. We also show that gradients are genetically controlled through multiple pathways. Based on these findings, we propose that cells in the Arabidopsis root meristem gradually transition from ‘stemness’ towards differentiation.
Project description:The recent release of a large number of genomes from ectomycorrhizal, orchid mycorrhizal and root endophytic fungi have provided deep insight into fungal lifestyle-associated genomic adaptation. Comparative analyses of symbiotic fungal taxa showed that similar outcomes of interactions in distant related root symbioses are examples of convergent evolution. The order Sebacinales represents a sister group to the Agaricomycetes (Basidiomycota) that is comprised of ectomycorrhizal, ericoid-, orchid- mycorrhizal, root endophytic fungi and saprotrophs (Oberwinkler et al., 2013). Sebacinoid taxa are widely distributed from arctic to temperate to tropical ecosystems and are among the most common and species-rich groups of ECM, OM and endophytic fungi (Tedersoo et al., 2012, Tedersoo et al., 2010, Oberwinkler et al., 2013). The root endophyte Piriformospora indica and the orchid mycorrhizal fungus S. vermifera (MAFF 305830) are non-obligate root symbionts which were shown to be able to interact with many different experimental hosts, including the non-mycorrhizal plant Arabidopsis thaliana. These two fungi display similar colonization strategies in barley and in Arabidopsis and the ability to establish beneficial interactions with different hosts (Deshmukh et al., 2006). Colonization of the roots by P. indica and S. vermifera results in enhanced seed germination and biomass production as well as increased resistance against biotic and abiotic stresses in its experimental hosts, including various members of the Brassicaceae family, barley, Nicotiana attenuata and switchgrass (Ghimire, 2011, Ghimire et al., 2009, Ghimire et al., 2011, Waller et al., 2008, Barazani et al., 2007, Deshmukh et al., 2006). Microarray experiments were performed to identify and characterize conserved sebacinoid genes as key determinants in the Sebacinales symbioses.
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.