Molecular mechanism of Arabidopsis thaliana seedlings in response to phytotoxicity of yttrium oxide nanoparticles
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ABSTRACT: Due to the wide application of rare earth oxides nanoparticles in different fields, they will inevitably be released into the environment, and their potential toxicity and ecological risks in the environment have become a concern of people. Yttrium oxide nanoparticles are important members of rare earth oxides nanoparticles. The molecular mechanism of its influence on plant growth and development and plant response to them is unclear. In this study, we found that yttrium oxide nanoparticles above 2 mM significantly inhibited the growth of Arabidopsis seedlings. Using the Arabidopsis marker lines reflecting auxin signal, it was found that the treatment of yttrium oxide nanoparticles led to the disorder of auxin signal in root cells: the auxin signal in quiescent center cells and columella stem cells decreased; while the auxin signal in the stele cells was enhanced. In addition, trypan blue staining showed that yttrium oxide nanoparticles caused the death of root cells. Transcriptome sequencing analysis showed that yttrium oxide nanoparticles specifically inhibited the expression of lignin synthesis related genes, activated mitogen-activated protein kinase (MAPK) signaling pathway, and enhanced ethylene and ABA signaling pathways in plants. This study revealed the phytotoxicity of yttrium oxide nanoparticles at the molecular level, and provided a new perspective at the molecular level for plants to respond to rare earth oxide stress.
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:Myosins are evolutionarily conserved motor proteins that interact with actin filaments to regulate organelle transport, cytoplasmic streaming and cell growth. Plant specific Class XI myosin proteins direct cell division and root organogenesis. However, the roles of Class VIII myosin proteins in plant growth and development are less understood. Here, we investigated the function of an auxin-regulated Class VIII myosin, Arabidopsis thaliana Myosin 1 (ATM1), using genetics and live cell microscopy. ATM1 is a plasmodesmata-localized protein that is enriched in actively dividing cells in the root apical meristem (RAM). Loss of ATM1 function results in impaired primary root growth due to decreased RAM size and reduced cell proliferation in a sugar dependent manner. Examination of stem cell marker line expression in atm1-1 indicated impaired division of the lateral root cap and columella cells and a diminished auxin response. Transcriptome analysis of atm1-1 linked these growth defects to dysregulation of cell cycle and auxin pathway genes. Complementation of ATM1 loss-of- function mutant restored root growth and cell cycle progression in the root meristem. Collectively, these results provide novel evidence that ATM1 functions to influence cell proliferation and differentiation in primary roots in response to auxin and sugar cues.
Project description:Root architecture is vital for plant growth and largely depends on primary root growth and lateral root development. Several plant hormones have been shown to affect root architecture among which auxin has been granted a central role. Lately, small signalling peptides also emerged as potential molecular components regulating root growth and development. Here, we identified C-TERMINALLY ENCODED PEPTIDE 5 (CEP5) as a novel, phloem poleexpressed paracrine signal for lateral root initiation. Our genetic, biochemical and pharmacological results show that CEP5 counteracts auxin signalling by stabilizing AUXIN/INDOLE ACETIC ACID (AUX/IAA) transcriptional repressors, suggesting the existence of an additional control mechanism through which plants can attenuate auxin signalling in a developmental context. Reducing CEP5 expression levels resulted in an increased auxin response and subsequently interfered with the normal progression through lateral root developmental stages.
Project description:2-day-old soybeans were treated with flooding and flooding with aluminum oxide nanoparticles of three varying sizes. Total proteins extracted from root including hypocotyl and mitochondrial proteins extracted from root tip were analyzed by nanoLC-MS/MS.
Project description:Root gravitropic response involves signal perception, signal transduction, asymetric auxin transport and differential cell elongation in the root tip. However, the regulatory mechanisms remain largely unknown. We used microarray to compare transcript profiles in the root tip samples of wild type and ngr mutant.
Project description:Metal oxide nanoparticles can exert adverse effects on humans and aquatic organisms. However, the toxic effects and mechanisms of MO-NPs are not clearly understood.We investigated the toxic effects and mechanisms of copper oxide, zinc oxide, and nickel oxide nanoparticles in Danio rerio using microarray analysis.