Differential regulation of serine acetyltransferase is involved in nickel hyperaccumulation in Thlaspi goesingense

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Mapping of ionomic traits in Mimulus guttatus reveals Mo and Cd QTLs that colocalize with MOT1 homologues

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The metal tolerance profile of Thlaspi goesingense is mimicked in Arabidopsis thaliana heterologously expressing serine acetyl-transferase

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Analysis of the root system architecture of Arabidopsis provides a quantitative readout of crosstalk between nutritional signals

As plant roots forage the soil for food and water, they translate a multifactorial input of environmental stimuli into a multifactorial developmental output that manifests itself as root system architecture (RSA). Our current understanding of the underlying regulatory network is limited because root responses have traditionally been studied separately for individual nutrient deficiencies. In this study, we quantified 13 RSA parameters of Arabidopsis thaliana in 32 binary combinations of N, P, K, S, and light. Analysis of variance showed that each RSA parameter was determined by a typical pattern of environmental signals and their interactions. P caused the most important single-nutrient effects, while N-effects were strongly light dependent. Effects of K and S occurred mostly through nutrient interactions in paired or multiple combinations. Several RSA parameters were selected for further analysis through mutant phenotyping, which revealed combinations of transporters, receptors, and kinases acting as signaling modules in K–N interactions. Furthermore, nutrient response profiles of individual RSA features across NPK combinations could be assigned to transcriptionally coregulated clusters of nutrient-responsive genes in the roots and to ionome patterns in the shoots. The obtained data set provides a quantitative basis for understanding how plants integrate multiple nutritional stimuli into complex developmental programs

Transcriptional activation and localization of expression of Brassica juncea putative metal transport protein BjMTP1

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Loss-of-Function of Constitutive Expresser of Pathogenesis Related Genes5 Affects Potassium Homeostasis in Arabidopsis thaliana

Here, we demonstrate that the reduction in leaf K+ observed in a mutant previously identified in an ionomic screen of fast neutron mutagenized Arabidopsis thaliana is caused by a loss-of-function allele of CPR5, which we name cpr5-3. This observation establishes low leaf K+ as a new phenotype for loss-of-function alleles of CPR5. We investigate the factors affecting this low leaf K+ in cpr5 using double mutants defective in salicylic acid (SA) and jasmonic acid (JA) signalling, and by gene expression analysis of various channels and transporters. Reciprocal grafting between cpr5 and Col-0 was used to determine the relative importance of the shoot and root in causing the low leaf K+ phenotype of cpr5. Our data show that loss-of-function of CPR5 in shoots primarily determines the low leaf K+ phenotype of cpr5, though the roots also contribute to a lesser degree. The low leaf K+ phenotype of cpr5 is independent of the elevated SA and JA known to occur in cpr5. In cpr5 expression of genes encoding various Cyclic Nucleotide Gated Channels (CNGCs) are uniquely elevated in leaves. Further, expression of HAK5, encoding the high affinity K+ uptake transporter, is reduced in roots of cpr5 grown with high or low K+ supply. We suggest a model in which low leaf K+ in cpr5 is driven primarily by enhanced shoot-to-root K+ export caused by a constitutive activation of the expression of various CNGCs. This activation may enhance K+ efflux, either indirectly via enhanced cytosolic Ca2+ and/or directly by increased K+ transport activity. Enhanced shoot-to-root K+ export may also cause the reduced expression of HAK5 observed in roots of cpr5, leading to a reduction in uptake of K+

Allelic heterogeneity and trade-off shape natural variation for response to soil micronutrient

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Molecular Dissection of the Cellular Mechanisms Involved in Nickel Hyperaccumulation in Plants

Phytoremediation, the use of plants for environmental cleanup of pollutants, including toxic metals, holds the potential to allow the economic restoration of heavy metal and radionuclide contaminated sites. A number of terrestrial plants are known to naturally accumulate high levels of metals in their shoots (1-2% dry weight), and these plants have been termed metal-hyperaccumulators. Clearly, the genetic traits that determines metal-hyperaccumulation offers the potential for the development of practical phytoremediation processes. Our long-term objective is to rationally design and generate plants ideally suited for phytoremediation using this unique genetic material. Initially, our strategy will focus on isolating and characterizing the key genetic information needed for expression of the metal-hyperaccumulation phenotype. Recently, histidine has been shown to play a major role in Ni hyperaccumulation. Based on this information we propose to investigate, at the molecular level, the role of histidine biosynthesis in Ni hyperaccumulation in Thlaspi goesingense, a Ni hyperaccumulator species. We will clone key genes involved in histidine biosynthesis. We will characterize their transcriptional and post transcriptional regulation by histidine, Ni. We will determine if any of these genes are essential and sufficient for Ni hyperaccumulation by their expression in the non-hyperaccumulator Arabidopsis thaliana

High-resolution genome-wide scan of genes, gene-networks and cellular systems impacting the yeast ionome

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