Phosphorylation-mediated dynamics of nitrate transceptor NRT1.1 regulate lateral root growth (Plant Physiol)

Nitrate is an important plant nutrient and multiple transporters have been identified in different plant species. NRT1.1 (NITRATE TRANSPORTER 1.1) belonging to the MFS (Major Facilitator Superfamily) has been shown to transport nitrate and auxin (IAA, Indole 3-acetic acid). This dual affinity transporter can switch from low- to high-nitrate affinity through differential phosphorylation of a threonine residue, Thr101. In this paper, Zhang et al. identified how this phosphorylation status can alter the transporter dynamics and thereby regulate lateral root growth. The authors altered the amino acid at position 101, to alter the phosphorylation status and found that the localization of the protein at the plasma membrane is altered. Non-phosphorylatable 101 residue led to oligomerization of the NRT1.1 transporter in the plasma membrane and altered auxin flux. This resulted in reduced lateral root growth in comparison to the plants expressing a phosphomimetic residue that can undergo regular phosphorylation. Through this work, NRT1.1 transporter regulation in response to phosphorylation of Thr101 has been shown to influence lateral root growth. (Summary by Suresh Damodaran) Plant Physiol. 10.1104/pp.19.00346