Phosphate Availability Alters Architecture and Causes Changes in Hormone Sensitivity in the Arabidopsis Root System

Abstract

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 (Ͻ50 m), 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.

Kin recognition is a nutrient-dependent inducible phenomenon

“…3). 24,25 Furthermore, exudates collected from seedlings grown at 0.10xMS, rather than 1xMS, are more effective at inducing lateral root formation (Fig. 4).…”

“…[22][23][24][25][26][27][28][29] Based on these prior observations we hypothesized that A. thaliana may utilize information regarding nutrient availability to influence decisions regarding competition based on neighbor identity. In other words, nutrient availability may influence the production of specific exudates associated with KR which could alter the RSA accordingly.…”

“…[22][23][24] Nitrogen and phosphorus deficiencies, for example, are well established modulators of lateral root development. 24,25 Nutrient availability also alters exudate production and composition with the potential to impact both interorganismal interactions as well as nutrient uptake.…”

“…[22][23][24] Nitrogen and phosphorus deficiencies, for example, are well established modulators of lateral root development. 24,25 Nutrient availability also alters exudate production and composition with the potential to impact both interorganismal interactions as well as nutrient uptake. [26][27][28][29] For example, in Sorghum bicolor reduced nitrogen and phosphorus levels promote the release of 5-deoxystrigol which encourages the recruitment of mycorrhizal fungi.…”

The Phosphate Fast-Responsive Genes PECP1 and PPsPase1 Affect Phosphocholine and Phosphoethanolamine Content

“…Root architecture can be modified to facilitate Pi uptake by favoring the development of lateral roots (at the expense of primary root elongation in many plants including Arabidopsis), increasing the density and length of root hairs, and limiting the development of aerial parts (López-Bucio et al, 2002;Svistoonoff et al, 2007;Gruber et al, 2013). Pi uptake mechanisms are enhanced at the root/soil interface, particularly through the stimulation of Pi transport activity (Mudge et al, 2002;Shin et al, 2004;Nussaume et al, 2011; Ayadi et al, 2015).…”