Premium
An Arabidopsis quiescin‐sulfhydryl oxidase regulates cation homeostasis at the root symplast–xylem interface
Author(s) -
Alejandro Santiago,
Rodríguez Pedro L,
Bellés Jose M,
Yenush Lynne,
GarcíaSanchez María J,
Fernández José A,
Serrano Ramón
Publication year - 2007
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7601757
Subject(s) - biology , humanities , symplast , valencia , botany , art , apoplast , cell wall , ecology
A genetic screen of Arabidopsis ‘activation‐tagging’ mutant collection based on tolerance to norspermidine resulted in a dominant mutant ( par1‐1D ) with increased expression of the QSO2 gene ( At1g15020 ), encoding a member of the quiescin‐sulfhydryl oxidase (QSO) family. The par1‐1D mutant and transgenic plants overexpressing QSO2 cDNA grow better than wild‐type Arabidopsis in media with toxic cations (polyamines, Li + and Na + ) or reduced K + concentrations. This correlates with a decrease in the accumulation of toxic cations and an increase in the accumulation of K + in xylem sap and shoots. Conversely, three independent loss‐of‐function mutants of QSO2 exhibit phenotypes opposite to those of par1‐1D . QSO2 is mostly expressed in roots and is upregulated by K + starvation. A QSO2∷GFP fusion ectopically expressed in leaf epidermis localized at the cell wall. The recombinant QSO2 protein, produced in yeast in secreted form, exhibits disulfhydryl oxidase activity. A plausible mechanism of QSO2 action consists on the activation of root systems loading K + into xylem, but different from the SKOR channel, which is not required for QSO2 action. These results uncover QSOs as novel regulators of ion homeostasis.