TABLE 1.

Localization of ion transporter (or channel) genes on the root cell.

Gene	Substrate	ep	ex	co	en	Polarity	References
AtNRT1.1	Nitrate	√		√	√		Huang et al.,1996
AtNRT2.1	Nitrate	√		√	√		Nazoa et al.,2003
AMT1;2	Ammonium				√		Neuhäuser et al.,2007
AtPT1	Phosphate	√			√		Karthikeyan et al.,2002
AKT1	Potasium	√		√	√		Lagarde et al.,1996
AtKC1	Potasium	√		√	√		Reintanz et al.,2002
AtYSL2	Iron/Zinc				√		Schaaf et al.,2005
AtIRT3	Iron/Zinc				√		Lin et al.,2009
NIP5;1	Boron	√		√	√	Distal	Takano et al.,2008
BOR1	Boron				√	Proximal	Takano et al.,2008
Nramp1	Manganese	√		√	√		Cailliatte et al.,2010
HvYSL2	Iron				√		Araki et al.,2011
HvST1	Sulfate	√		√	√		Rae and Smith,2002
HvLsi2	Silicon				√		Mitani et al.,2009
ZmLsi2	Silicon				√		Mitani et al.,2009
OsPT8	Phosphate	√		√	√		Jia et al.,2011
OsAKT1	Potasium	√	√	√	√		Li et al.,2014
OsYLS15	Iron	√	√	√	√		Lee et al.,2009
OsLsi1	Silicon		√		√	Distal	Ma et al.,2006
OsLsi2	Silicon		√		√	Proximal	Ma and Yamaji,2015
OsNramp5	Manganese/Cadmium		√		√	Distal	Sasaki et al.,2012
OsMTP9	Manganese		√		√	Proximal	Ueno et al.,2015
OsNIP3;1	Boron		√		√	Distal	Takano et al.,2008
OsBOR1	Boron		√		√	Proximal	Nakagawa et al.,2007

^*Slash represents the species lacking exodermal cell. ep, Epidermis; ex, exodermis; co, cortex; en, endodermis.