title: Responses of root architecture development to low phosphorus availability: a review.
abstract: BACKGROUND
  Phosphorus (P) is an essential element for plant growth and development but it is often a limiting nutrient in soils. Hence, P acquisition from soil by plant roots is a subject of considerable interest in agriculture, ecology and plant root biology. Root architecture, with its shape and structured development, can be considered as an evolutionary response to scarcity of resources.
  
  
  METHODS
  This review discusses the significance of root architecture development in response to low P availability and its beneficial effects on alleviation of P stress. It also focuses on recent progress in unravelling cellular, physiological and molecular mechanisms in root developmental adaptation to P starvation. The progress in a more detailed understanding of these mechanisms might be used for developing strategies that build upon the observed explorative behaviour of plant roots.
  
  
  CONCLUSIONS
  The role of root architecture in alleviation of P stress is well documented. However, this paper describes how plants adjust their root architecture to low-P conditions through inhibition of primary root growth, promotion of lateral root growth, enhancement of root hair development and cluster root formation, which all promote P acquisition by plants. The mechanisms for activating alterations in root architecture in response to P deprivation depend on changes in the localized P concentration, and transport of or sensitivity to growth regulators such as sugars, auxins, ethylene, cytokinins, nitric oxide (NO), reactive oxygen species (ROS) and abscisic acid (ABA). In the process, many genes are activated, which in turn trigger changes in molecular, physiological and cellular processes. As a result, root architecture is modified, allowing plants to adapt effectively to the low-P environment. This review provides a framework for understanding how P deficiency alters root architecture, with a focus on integrated physiological and molecular signalling.
authors.affiliation: Ministry of Education Key Laboratory of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
authors.forename: Yao Fang
authors.initials: YF
authors.lastname: Niu
authors.forename: Ru Shan
authors.initials: RS
authors.lastname: Chai
authors.forename: Gu Lei
authors.initials: GL
authors.lastname: Jin
authors.forename: Huan
authors.initials: H
authors.lastname: Wang
authors.forename: Cai Xian
authors.initials: CX
authors.lastname: Tang
authors.forename: Yong Song
authors.initials: YS
authors.lastname: Zhang
mesh_terms: D000222:Adaptation, Physiological; D001692:Biological Transport; D018506:Gene Expression Regulation, Plant; D009569:Nitric Oxide; D010758:Phosphorus / Q000378:metabolism*; D063245:Plant Development; D010937:Plant Growth Regulators / Q000378:metabolism; D018517:Plant Roots / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D010944:Plants / Q000033:anatomy & histology / Q000235:genetics* / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D010937:Plant Growth Regulators; D017382:Reactive Oxygen Species; D010758:Phosphorus; D009569:Nitric Oxide