title: Rhizosheaths on wheat grown in acid soils: phosphorus acquisition efficiency and genetic control.
abstract: Rhizosheaths comprise soil bound to roots, and in wheat (Triticum aestivum L.) rhizosheath size correlates with root hair length. The aims of this study were to determine the effect that a large rhizosheath has on the phosphorus (P) acquisition by wheat and to investigate the genetic control of rhizosheath size in wheat grown on acid soil.Near-isogenic wheat lines differing in rhizosheath size were evaluated on two acid soils. The soils were fertilized with mineral nutrients and included treatments with either low or high P. The same soils were treated with CaCO3 to raise the pH and detoxify Al(3+) Genotypic differences in rhizosheath size were apparent only when soil pH was low and Al(3+) was present. On acid soils, a large rhizosheath increased shoot biomass compared with a small rhizosheath regardless of P supply. At low P supply, increased shoot biomass could be attributed to a greater uptake of soil P, but at high P supply the increased biomass was due to some other factor. Generation means analysis indicated that rhizosheath size on acid soil was controlled by multiple, additive loci. Subsequently, a quantitative trait loci (QTL) analysis of an F6 population of recombinant inbred lines identified five major loci contributing to the phenotype together accounting for over 60% of the total genetic variance. One locus on chromosome 1D accounted for 34% of the genotypic variation. Genetic control of rhizosheath size appears to be relatively simple and markers based on the QTL provide valuable tools for marker assisted breeding.
authors.affiliation: CSIRO Agriculture, PO Box 1600, Canberra, ACT 2601, Australia.
authors.forename: Richard A
authors.initials: RA
authors.lastname: James
authors.affiliation: CSIRO Agriculture, PO Box 1600, Canberra, ACT 2601, Australia.
authors.forename: Chandrakumara
authors.initials: C
authors.lastname: Weligama
authors.affiliation: CSIRO Data61 , PO Box 1600, Canberra, ACT 2601, Australia.
authors.forename: Klara
authors.initials: K
authors.lastname: Verbyla
authors.affiliation: CSIRO Agriculture, PO Box 1600, Canberra, ACT 2601, Australia.
authors.forename: Peter R
authors.initials: PR
authors.lastname: Ryan
authors.affiliation: CSIRO Agriculture, PO Box 1600, Canberra, ACT 2601, Australia.
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Rebetzke
authors.affiliation: Dow AgroSciences, Canberra, ACT 2601, Australia.
authors.forename: Allan
authors.initials: A
authors.lastname: Rattey
authors.affiliation: CSIRO Agriculture, PO Box 1600, Canberra, ACT 2601, Australia.
authors.forename: Alan E
authors.initials: AE
authors.lastname: Richardson
authors.affiliation: CSIRO Agriculture, PO Box 1600, Canberra, ACT 2601, Australia manny.delhaize@csiro.au.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Delhaize
mesh_terms: D006863:Hydrogen-Ion Concentration; D010758:Phosphorus / Q000378:metabolism*; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development; D040641:Quantitative Trait Loci; D012987:Soil / Q000737:chemistry; D014908:Triticum / Q000235:genetics* / Q000254:growth & development*
chemical_list: D012987:Soil; D010758:Phosphorus
keywords: Acid soil; aluminum toxicity; genetics; heritability; phosphorus acquisition efficiency; rhizosheath; root hairs.