Plants without arbuscular mycorrhizae
Although mycorrhizal symbioses (described elsewhere in this volume) are the most important adaptation for angiosperms to acquire scarce phosphorus (P), many plant families contain species that either do not form or rarely form this pivotal association (Skene 1998; Miller et al. 1999; Cripps and Eddington 2005; Miller 2005). This review will address adaptations and mechanisms for acquisition and use of scarce P in plants lacking effective mycorrhizal symbioses. The primary focus will be on root adaptations in species that develop specialized-complex roots (cluster and dauciform) in response to P deficiency. Although not producing cluster or dauciform roots in response to P deficiency, Arabidopsis will also be considered because it does not form mycorrhizal symbiosis and is a model species for evaluating plant adaptation to P deficiency.
Plants have evolved two broad strategies for improved P acquisition and use in nutrient-limiting environments: (1) those aimed at conservation of use; and (2) those directed toward enhanced acquisition or uptake (Vance et al. 2003; Ticconi and Abel 2004; Misson et al. 2005; Morcuende et al. 2007). Processes that conserve the use of P involve decreased growth rate, increased growth per unit of P uptake, remobilization of internal P, modifications in carbon (C) metabolism that bypass P-requiring steps, alternative respiratory pathways, and alterations in membrane biosynthesis requiring less P (Plaxton and Carswell 1999; Uhde-Stone et al. 2003a,b; Wasaki et al. 2003; Misson et al. 2005; Lambers et al. 2006). In comparison, processes that lead to enhanced P uptake include modified root architecture and greater root growth, prolific development of root hairs leading to expanded root surface area, enhanced expression of Pi transporter genes, and increased production and exudation of phosphatases and organic acids (Marschner et al. 1986; López- Bucio et al. 2002; Shane and Lambers 2005). These numerous adaptive responses to P-deficiency are not mutually exclusive and all may occur within a single species.
KeywordsLateral Root Root Hair Plant Cell Environ Root Architecture White Lupin
Unable to display preview. Download preview PDF.
- Charlton WA (1996) Lateral root initiation. In: Waisel Y, Eshel A, Kafkafi U (eds), Plant Roots: The Hidden Half (2nd edition). Marcel Dekker, New YorkGoogle Scholar
- Dinkelaker B, Hengeler C, Marschner H (1995) Distribution and function of proteoid roots and other root clusters. Bot Acta 108: 183–200Google Scholar
- Emery NRJ, Atkins CA (2002) Roots and cytokinins. In: Waisel Y, Eshel A, Kafkafi U (eds), Plant Roots: The Hidden Half (3rd edition). Marcel Dekker, New York, pp 417–434Google Scholar
- Hernández G, Ramirez M, Valdés-López O, Tesfaye M, Graham MA, Czechowski T, Schlereth A, Wandrey M, Erban A, Cheung F, Wu HC, Lara M, Town CD, Kopka J, Udvardi MK, Vance CP (2007) Phosphorus stress in common bean: root transcript and metabolic responses. Plant Physiol 144: 752–767PubMedCrossRefGoogle Scholar
- Massonneau A, Langlade N, Léon S, Smutny J, Vogt E, Neumann G, Martinoia E (2001) Metabolic changes associated with cluster root development in white lupin (Lupinus albus L.): relationship between organic acid excretion, sucrose metabolism and energy status. Planta 213: 534–542PubMedCrossRefGoogle Scholar
- Misson J, Raghothama KG, Jain A, Jouhet J, Block MA, Bligny R, Ortet P, Creff A, Somerville S, Rolland N, Doumas P, Nacry P, Herrerra-Estrella L, Nussaume L, Thibaud M-C (2005) A genome-wide transcriptional analysis using Arabidopsis thaliana Affymetrix gene chips determined plant responses to phosphate deprivation. Proc Natl Acad Sci USA 102: 11934–11939PubMedCrossRefGoogle Scholar
- Pate J, Watt M (2001) Roots of Banksia spp. (Proteacea) with special reference to functioning of their specialized root clusters. In: Waisel Y, Eshel A, Kafkafi U (eds), Plant Roots: The Hidden Half (3rd edition). Marcel Dekker, New York, pp 989–1006Google Scholar
- Peterson RL, Farquhar ML (1996) Root hairs: specialized tubular cells extending root surfaces. Bot Gaz 62: 1–40Google Scholar
- Plaxton WC, Carswell MC (1999) Metabolic aspects of the phosphate starvation response in plants. In: Lerner HR (ed), Plant Responses to Environmental Stresses: From Phytohormones to Genome Reorganisation. Dekker, New York, pp 349–372Google Scholar
- Shane MW, Cramer MD, Funayama-Noguchi S, Cawthray GR, Millar AH, Day DA, Lambers H (2004) Developmental physiology of cluster-root carboxylate synthesis and exudation in harsh Hakea. Expression of phosphoenolpyruvate carboxylase and the alternative oxidase. Plant Physiol 135: 549–560PubMedCrossRefGoogle Scholar
- Steen I (1997) Phosphorus availability in the 21st century. Management of a non-renewable resource. Phosphorus Potassium 217: 25–31Google Scholar
- Weisskopf L, Abou-Mansour E, Fromin N, Tomasi N, Santelia D, Edelkott I, Neumann G, Aragno M, Tabacchi R, Martinoia E (2006a) White lupin has developed a complex strategy to limit microbial degradation of secreted citrate required for phosphate acquisition. Plant Cell Environ 29: 919–927PubMedCrossRefGoogle Scholar
- Werner T, Motyka V, Laucou V, Smets R, Van Onckelen H, Schmülling T (2003) Cytokinin-deficient transgenic Arabidopsis plants show multiple developmental alterations indicating opposite functions of cytokinins in the regulation of shoot and root meristem activity. Plant Cell 15: 2532–2550PubMedCrossRefGoogle Scholar