About the Editors William Plaxton is currently a Full Professor and Queen’s Research Chair in the Department of Biology at Queen’s University, Kingston, Canada. Hans Lambers is Professor of Plant Physiological Ecology in the School of Plant Biology at the University of Western Australia, Perth, Australia.

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• List of Contributors xviiPreface xxiiiSection I Introduction1 Phosphorus: Back to the Roots 3Hans Lambers and William C. Plaxton1.1 Introduction 31.2 Phosphorus or phosphorous? 41.3 Phosphorus on a geological time scale 61.4 Phosphorus as an essential, but frequently limiting, soil nutrient for plant productivity 71.5 Soil phosphorus pools 91.6 Soil phosphorus mobility 101.7 Factors determining rates of phosphorus uptake by roots 111.8 Phosphorus-starvation responses: does phosphorus homeostasis exist? 131.9 Concluding remarks 14Acknowledgements 15References 15Section II P-Sensing, Transport, and Metabolism2 Sensing, Signalling, and Control of Phosphate Starvation in Plants: Molecular Players and Applications 25Wolf-Rüdiger Scheible and Monica Rojas-Triana2.1 Introduction 252.2 The plant phosphate-starvation response 262.3 Sensing of phosphate and other macronutrient limitations in plants 292.3.1 Nutrient transporters as sensors/receptors 292.3.2 Local Pi sensing and signalling at the root tip by PDR2/LPR1 312.3.3 Phosphite, a tool to investigate P-sensing/signalling 312.4 Signalling of phosphate limitation 322.4.1 The role of phytohormones 332.4.2 Systemic signalling during P-starvation 372.4.3 Transcriptional regulators involved in P-signalling and affecting P-starvation responses 392.4.4 The role of microRNAs and targeted protein degradation in P-signalling 412.4.5 Additional regulators of P-signalling 432.5 Improving plant P-acquisition and -utilization efficiency: approaches and targets 442.6 Concluding remarks 48References 493 ‘Omics’ Approaches Towards Understanding Plant Phosphorus Acquisition and Use 65Ping Lan, Wenfeng Li and Wolfgang Schmidt3.1 Introduction 663.2 Towards a transcriptomics-derived ‘phosphatome’ 673.3 Pi deficiency-induced alterations in the proteome 773.4 Core PSR proteins 803.5 Membrane lipid remodelling: insights from the transcriptome, the proteome, and the lipidome 833.6 Genome-wide histone modifications in Pi-deficient plants 863.7 Conclusions and outlook 893.8 Acknowledgements 90References 904 The Role of Post-Translational Enzyme Modifications in the Metabolic Adaptations of Phosphorus-Deprived Plants 99William C. Plaxton and Michael W. Shane4.1 Introduction 1004.2 In the beginning there was protein phosphorylation 1014.3 Monoubiquitination has emerged as a crucial PTM that interacts with phosphorylation to control the function of diverse proteins 1044.4 Post-translational modification of plant phosphoenolpyruvate carboxylase by phosphorylation versusmonoubiquitination 1074.4.1 Activation of PEP carboxylase by in-vivo phosphorylation appears to be a universal aspect ofthe plant P-starvation response 1074.4.2 PEP carboxylase monoubiquitination: an old dog learns new tricks 1094.4.3 Reciprocal control of PEP carboxylase by in-vivo monoubiquitination and phosphorylation indeveloping proteoid roots of P-deficient harsh hakea 1114.5 Glycosylation is a sweet PTM of glycoproteins 1144.5.1 A pair of AtPAP26 glycoforms is upregulated and secreted by P-deprived Arabidopsis 1154.5.2 The AtPAP26-S2 glycoform copurifies with, and appears to interact with, a curculin-like lectin 1164.6 Concluding remarks 117Acknowledgements 118References 1195 Phosphate Transporters 125Yves Poirier and Ji-Yul Jung5.1 Introduction 1255.2 The PHT1 transporters 1265.2.1 PHT1 structure, activity, and expression patterns 1265.3 Control of PHT1 activity 1305.3.1 Control of PHT1 transcript levels 1305.3.2 Post-transcriptional control of PHT1 1335.4 PHO1 and phosphate export 1365.4.1 PHO1 structure, activity, and expression patterns 1365.4.2 Transcriptional control of PHO1 expression 1395.4.3 Post-transcriptional control of PHO1 1395.5 Phosphate transporters of organelles 1405.5.1 Mitochondrial phosphate transporters 1405.5.2 Plastidial phosphate transporters 1415.5.3 The role of PHT2 in plastid phosphate transport 1435.5.4 The role of PHT4 in plastid phosphate transport 1435.6 Phosphate transporters of other organelles 1455.6.1 Golgi phosphate transporters 1455.6.2 Peroxisomal phosphate transporters 1465.6.3 Vacuolar (tonoplast) phosphate transporters 1465.7 Concluding remarks 146Acknowledgements 147References 1476 Molecular Components that Drive Phosphorus-Remobilisation During Leaf Senescence 159Aaron P. Smith, Elena B. Fontenot, Sara Zahraeifard and Sandra Feuer DiTusa6.1 Introduction 1596.2 Transcriptomes of senescence and phosphate-deficiency 1606.3 Major biochemical components that mediate P-remobilisation during leaf senescence 1626.3.1 Nucleases 1636.3.2 Phosphatases 1666.3.3 Lipid-remodelling enzymes 1686.3.4 Pi transporters 1696.4 Regulatory and signalling components of senescing leaves 1706.4.1 Transcription factors 1706.4.2 The SPX superfamily 1736.4.3 Ubiquitination components and miRNAs 1746.5 Role of hormones during leaf senescence 1756.5.1 Ethylene and strigolactones 1756.5.2 Abscisic acid 1766.5.3 Cytokinins 1766.6 Concluding remarks 176Acknowledgements 177References 1777 Interactions Between Nitrogen and Phosphorus Metabolism 187John A. Raven7.1 Introduction 1887.2 Roles of N and P in plants and the extent to which compounds containing N or P can be substituted by compounds lacking N or P 1887.3 Variability in the N:P ratio in plants and its metabolic and ecological significance 1957.3.1 Fixed N:P ratios: the role of compounds containing both N and P 1957.3.2 Protein:RNA ratio, organism N:P ratio, the Growth Rate Hypothesis 1977.3.3 Organism N and P concentration as a function of external supply of N and P 2007.3.4 Conclusions 2017.4 Interactions in N and P acquisition and assimilation 2017.4.1 Structures involved in acquisition of N and P 2027.4.2 Secretion of enzymes and organic anions facilitates root N and P acquisition 2047.5 Protein synthesis and protein degradation during P-deprivation: significance for N–P interaction 2077.6 General conclusions 207Acknowledgements 208References 208Section III P-deprivation Responses8 Metabolomics of Plant Phosphorus-Starvation Response 217Chris Jones, Jean-Hugues Hatier, Mingshu Cao, Karl Fraser and Susanne Rasmussen8.1 Introduction 2188.2 Metabolomic approaches 2198.3 Metabolomic analysis platforms 2208.4 Data analysis 2228.5 Metabolomics strategies directed at dissecting responses to P starvation 2238.6 Opportunities for metabolomics to contribute to the development of P-efficient crops 2298.7 Future prospects 230Acknowledgements 231References 2319 Membrane Remodelling in Phosphorus-Deficient Plants 237Meike Siebers, Peter Dörmann and Georg Hölzl9.1 Introduction 2379.2 Membrane lipid remodelling during phosphate deprivation 2389.3 Monogalactosyldiacylglycerol (MGDG) 2429.4 Digalactosyldiacylglycerol (DGDG) 2439.5 Sulfolipid (SQDG) and glucuronosyldiacylglycerol (GlcADG) 2479.6 Phospholipid degradation by phospholipase D and phosphatidate phosphatase 2489.7 Phospholipase C (PLC) 2499.8 Acyl hydrolases 2509.9 Lipid trafficking under phosphate starvation 2509.10 Glucosylceramide, sterol glucoside, and acylated sterol glucoside 2539.11 The role of auxin in remodelling of membrane lipid composition 2549.12 Improved Pi status by symbiosis with arbuscular mycorrhizal fungi 2559.13 Outlook 255References 25610 The Role of Intracellular and Secreted Purple Acid Phosphatases in Plant Phosphorus Scavenging and Recycling 265Jiang Tian and Hong Liao10.1 Introduction 26610.2 Bioinformatics and structural analysis of plant PAPs 26610.2.1 PAP bioinformatics 26610.2.2 Structural biochemistry of plant PAPs 26910.3 Biochemical characterisation of plant PAPs 26910.4 Diverse subcellular localisation of plant PAPs 27110.5 Transcriptional and post-transcriptional regulation of PAP expression by P availability 27510.5.1 Complex signal transduction pathways integrate nutritional P status with PAP expression 27610.5.2 Post-translational PAP modification 27710.6 Functional analysis of PAPs involved in P mobilization and utilisation 27810.7 Perspectives 281Acknowledgements 282References 28211 Metabolic Adaptations of the Non-Mycotrophic Proteaceae to Soils With Low Phosphorus Availability 289Hans Lambers, Peta L. Clode, Heidi-Jayne Hawkins, Etienne Laliberté, Rafael S. Oliveira, Paul Reddell, Michael W. Shane, Mark Stitt and Peter Weston11.1 Introduction 29011.2 Phosphorus nutrition of Proteaceae, with a focus on south-western Australia 29111.2.1 Phosphorus acquisition by non-mycorrhizal roots: cluster roots 29111.2.2 Proteaceae species that do not produce cluster roots 29811.2.3 Phosphorus toxicity 29911.2.4 High rates of photosynthesis despite low leaf P concentrations 30011.2.5 Leaf longevity 30711.2.6 Delayed greening 30811.2.7 Efficient and proficient P remobilisation from senescing organs 31011.2.8 Seed Preserves 31111.3 Comparison of species of Proteaceae in south-western Australia with species elsewhere 31211.3.1 The Cape Floristic Region in South Africa 31211.3.2 Eastern Australia 31411.3.3 Southern South America 31611.3.4 Brazil 31711.4 Perspectives 318Acknowledgements 323References 32312 Algae in a Phosphorus-Limited Landscape 337Arthur R. Grossman and Munevver Aksoy12.1 Introduction 33812.2 P-deprivation responses of green algae and vascular plants 33912.2.1 Phosphatases 34212.2.2 Nucleases 34612.2.3 Pi transport 34812.2.4 Polyphosphates 35012.2.5 Phospholipids 35112.3 Control of P deprivation responses 35312.3.1 PSR1-dependent gene expression in P-starved algae 35612.3.2 Low-phosphate bleaching mutants 35812.4 Future prospects 359Acknowledgements 360References 360Section IV Significance of Plant–Microbe Interactions for P-Acquisition and Metabolism13 Impact of Roots, Microorganisms and Microfauna on the Fate of Soil Phosphorus in the Rhizosphere 377Philippe Hinsinger, Laetitia Herrmann, Didier Lesueur, Agnès Robin, Jean Trap, Kittima Waithaisong and Claude Plassard13.1 Introduction 37813.2 Spatial extension of the rhizosphere 37813.2.1 Root architecture and growth 37913.2.2 Root hairs and mycorrhizas 38013.2.3 Root growth-promoting effect of rhizosphere biota 38113.3 Mobilisation of inorganic P in the rhizosphere 38513.3.1 Effect of rhizosphere pH changes 38513.3.2 Effect of exudation of carboxylates 38713.4 Mobilisation of organic P in the rhizosphere 38913.4.1 Effects of phosphatases 39013.4.2 Effects of phytases 39113.5 Microbial P, microbial loop, and P recycling in the rhizosphere 39313.5.1 Abiotic processes 39313.5.2 Biotic processes 39413.6 Conclusions and future prospects 397References 39814 Mycorrhizal Associations and Phosphorus Acquisition: From Cells to Ecosystems 409Sally E. Smith, Ian C. Anderson and F. Andrew Smith14.1 Introduction 41014.2 Arbuscular mycorrhizas 41314.2.1 Establishment of the symbiosis 41314.2.2 Specialised AM interfaces in soil and roots are critical for P uptake 41314.2.3 The AM pathway in plant P nutrition 41614.2.4 The ‘mutualism–parasitism’ continuum 41714.2.5 Some higher-scale issues in AM symbiosis 41814.2.6 Significance of AM symbioses in agriculture and horticulture 41914.3 Ectomycorrhizas 42114.3.1 Establishment of the symbiosis 42114.3.2 Roles of ectomycorrhizas in plant P nutrition 42214.3.3 ECM phosphate transporters 42314.3.4 Solubilisation of inorganic phosphates by ECM fungi 42514.3.5 Mobilisation of organic-P sources by ECM fungi 42614.3.6 ECM symbioses and forest tree P nutrition: future challenges 42814.4 Conclusions 429References 430Index 441