The efficiency of Arabidopsis thaliana (Brassicaceae) root hairs in phosphorus acquisition

Abstract

Arabidopsis thaliana root hairs grow longer and denser in response to low-phosphorus availability. In addition, plants with the root hair response acquire more phosphorus than mutants that have root hairs that do not respond to phosphorus limiting conditions. The purpose of this experiment was to determine the efficiency of root hairs in phosphorus acquisition at high- and low-phosphorus availability. Root hair growth, root growth, root respiration, plant phosphorus uptake, and plant phosphorus content of 3-wk-old wild-type Arabidopsis (WS) were compared to two root hair mutants (rhd6 and rhd2) under high (54 mmol/m) and low (0.4 mmol/m) phosphorus availability. A cost-benefit analysis was constructed from the measurements to determine root hair efficiency. Under high-phosphorus availability, root hairs did not have an effect on any of the parameters measured. Under low-phosphorus availability, wild-type Arabidopsis had greater total root surface area, shoot biomass, phosphorus per root length, and specific phosphorus uptake. The cost-benefit analysis shows that under low phosphorus, wild-type roots acquire more phosphorus for every unit of carbon respired or unit of phosphorus invested into the roots than the mutants. We conclude that the response of root hairs to low-phosphorus availability is an efficient strategy for phosphorus acquisition.

Root system architecture: insights fromArabidopsisand cereal crops

“…ROOT SYSTEM ARCHITECTURE RSA on a macroscale describes the organization of the primary and lateral roots, and also accessory roots (including other root types found in cereals) where they are present, and is a key determinant of nutrientand water-use efficiency in plants. On a microscale, this includes root hairs that increase the surface area, aiding with uptake of water and nutrients [21][22][23][24][25]. In both dicots and monocots, adventitious roots are also sometimes formed post-embryonically at the rootshoot junction, for example to explore and exploit the phosphorus-rich upper soil strata ( figure 1a,b).…”

Phene Synergism between Root Hair Length and Basal Root Growth Angle for Phosphorus Acquisition

“…basic units of the phenotype; Serebrovsky, 1925;Lynch, 2011; for discussion, see York et al, 2013) enhance phosphorus acquisition, including root architectural phenes for topsoil foraging , such as shallow root growth angles Ho et al, 2005), increased basal root whorl number (Lynch and Brown, 2012;Miguel et al, 2013), and adventitious rooting (Miller et al, 2003); phenes to enhance soil exploitation, including root hair length and density (RHL/D; Bates and Lynch, 2000a, 2000bMa et al, 2001a;Gahoonia and Nielsen, 2004;Yan et al, 2004) and phosphorus-solubilizing root exudates (Ryan et al, 2001); mycorrhizal symbioses (Smith and Read, 2008); and phenes that reduce the metabolic cost of soil exploration , such as root etiolation and root cortical aerenchyma (Fan et al, 2003;Lynch, 2010, 2011). It is probable that interactions among these phenes are important in determining the phosphorus acquisition of integrated phenotypes.…”

“…RHL/D are also important for phosphorus acquisition (Bates and Lynch, 2000a, 2000bGahoonia and Nielsen, 2004). Since phosphorus mobility in soil is governed by diffusion rather than mass flow, phosphorus uptake by roots is limited by localized phosphorus depletion in the rhizosphere (Barber, 1995).…”

Live Imaging of Inorganic Phosphate in Plants with Cellular and Subcellular Resolution

“…These mechanisms include secretion of organic acids and phosphatases (Vance et al, 2003), increased growth of lateral roots and root hairs (Bates and Lynch, 2000;Péret et al, 2011), production of high-affinity Pi transporters at the root-soil interface (Misson et al, 2004;Shin et al, 2004), formation of symbiotic association with mycorrhizal fungi, which enhances Pi scavenging capabilities (Javot et al, 2007), modification of metabolic pathways (Plaxton and Tran, 2011), and altered patterns of Pi translocation between organs and transport between subcellular compartments (Walker and Sivak, 1986;Mimura, 1999;Raghothama, 1999). Substantial insights have been gained into the underlying biochemical identities and regulatory strategies for such adaptive responses, including those related to sensing and signaling of Pi status (Rouached et al, 2010;Chiou and Lin, 2011;Plaxton and Tran, 2011;Jain et al, 2012;Liu et al, 2014;Zhang et al, 2014).…”