Phosphate availability alters architecture and causes changes in hormone sensitivity in the Arabidopsis root system.
The postembryonic developmental program of the plant root system is plastic and allows changes in root architecture to adapt to environmental conditions such as water and nutrient availability. Among essential nutrients, phosphorus (P) often limits plant productivity because of its low mobility in soil. Therefore, the architecture of the root system may determine the capacity of the plant to acquire this nutrient. We studied the effect of P availability on the development of the root system in Arabidopsis. We found that at P-limiting conditions (<50 microM), the Arabidopsis root system undergoes major architectural changes in terms of lateral root number, lateral root density, and primary root length. Treatment with auxins and auxin antagonists indicate that these changes are related to an increase in auxin sensitivity in the roots of P-deprived Arabidopsis seedlings. It was also found that the axr1-3, axr2-1, and axr4-1 Arabidopsis mutants have normal responses to low P availability conditions, whereas the iaa28-1 mutant shows resistance to the stimulatory effects of low P on root hair and lateral root formation. Analysis of ethylene signaling mutants and treatments with 1-aminocyclopropane-1-carboxylic acid showed that ethylene does not promote lateral root formation under P deprivation. These results suggest that in Arabidopsis, auxin sensitivity may play a fundamental role in the modifications of root architecture by P availability.
López-Bucio
José
J
Departamento de Ingeniería Genética de Plantas, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Unidad Irapuato, Apartado postal 629, 36500 Irapuato, Guanajuato, Mexico.
Hernández-Abreu
Esmeralda
E
Sánchez-Calderón
Lenin
L
Nieto-Jacobo
María Fernanda
MF
Simpson
June
J
Herrera-Estrella
Luis
L
D015084:2,4-Dichlorophenoxyacetic Acid / Q000494:pharmacology; D000598:Amino Acids, Cyclic / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D001692:Biological Transport / Q000502:physiology; D003583:Cytokinins / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005030:Ethylenes / Q000494:pharmacology; D007210:Indoleacetic Acids / Q000494:pharmacology; D009154:Mutation; D010710:Phosphates / Q000494:pharmacology*; D010937:Plant Growth Regulators / Q000494:pharmacology*; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development*; D018520:Plant Shoots / Q000187:drug effects / Q000254:growth & development; D014283:Triiodobenzoic Acids / Q000494:pharmacology; D015026:Zeatin / Q000494:pharmacology
D000598:Amino Acids, Cyclic; D003583:Cytokinins; D005030:Ethylenes; D007210:Indoleacetic Acids; D010710:Phosphates; D010937:Plant Growth Regulators; D014283:Triiodobenzoic Acids; D015084:2,4-Dichlorophenoxyacetic Acid; C023863:1-aminocyclopropane-1-carboxylic acid; D015026:Zeatin; C036216:ethylene; C052968:2,3,5-triiodobenzoic acid