TY - JOUR

T1 - Rhizosecretion of stele-synthesized glucosinolates and their catabolites requires GTR-mediated import in Arabidopsis

AU - Xu, Deyang

AU - Hanschen, Franziska S.

AU - Witzel, Katja

AU - Nintemann, Sebastian

AU - Nour-Eldin, Hussam Hassan

AU - Schreiner, Monika

AU - Halkier, Barbara Ann

PY - 2017

Y1 - 2017

N2 - Casparian strip-generated apoplastic barriers not only control the radial flow of both water and ions but may also constitute a hindrance for the rhizosecretion of stele-synthesized phytochemicals. Here, we establish root-synthesized glucosinolates (GLS) are in Arabidopsis as a model to study the transport routes of plant-derived metabolites from the site of synthesis to the rhizosphere. Analysing the expression of GLS synthetic genes in the root indicate that the stele is the major site for the synthesis of aliphatic GLS, whereas indole GLS can be synthesized in both the stele and the cortex. Sampling root exudates from the wild type and the double mutant of the GLS importers GTR1 and GTR2 show that GTR-mediated retention of stele-synthesized GLS is a prerequisite for the exudation of both intact GLS and their catabolites into the rhizosphere. The expression of the GTRs inside the stele, combined with the previous observation that GLS are exported from biosynthetic cells, suggest three possible routes of stele-synthesized aliphatic GLS after their synthesis: (i) GTR-dependent import to cells symplastically connected to the cortical cells and the rhizosphere; (ii) GTR-independent transport via the xylem to the shoot; and (iii) GTR-dependent import to GLS-degrading myrosin cells at the cortex. The study suggests a previously undiscovered role of the import process in the rhizosecretion of root-synthesized phytochemicals.

AB - Casparian strip-generated apoplastic barriers not only control the radial flow of both water and ions but may also constitute a hindrance for the rhizosecretion of stele-synthesized phytochemicals. Here, we establish root-synthesized glucosinolates (GLS) are in Arabidopsis as a model to study the transport routes of plant-derived metabolites from the site of synthesis to the rhizosphere. Analysing the expression of GLS synthetic genes in the root indicate that the stele is the major site for the synthesis of aliphatic GLS, whereas indole GLS can be synthesized in both the stele and the cortex. Sampling root exudates from the wild type and the double mutant of the GLS importers GTR1 and GTR2 show that GTR-mediated retention of stele-synthesized GLS is a prerequisite for the exudation of both intact GLS and their catabolites into the rhizosphere. The expression of the GTRs inside the stele, combined with the previous observation that GLS are exported from biosynthetic cells, suggest three possible routes of stele-synthesized aliphatic GLS after their synthesis: (i) GTR-dependent import to cells symplastically connected to the cortical cells and the rhizosphere; (ii) GTR-independent transport via the xylem to the shoot; and (iii) GTR-dependent import to GLS-degrading myrosin cells at the cortex. The study suggests a previously undiscovered role of the import process in the rhizosecretion of root-synthesized phytochemicals.

U2 - 10.1093/jxb/erw355

DO - 10.1093/jxb/erw355

M3 - Journal article

C2 - 27702989

VL - 68

SP - 3205

EP - 3214

JO - Journal of Experimental Botany

JF - Journal of Experimental Botany

SN - 0022-0957

IS - 12

ER -