Table 3.

Functional properties of Cl⁻ transport proteins potentially involved in Cl⁻ nutrition: net uptake and/or long-distance transport.

Protein Name	Localization	Cell Function	Biological Role	References
ZmNPF6.4	Plasma membrane of root and shoot tissues	High affinity Cl− selective H+/Cl− symporter Cl− influx	Undetermined	[147]
ZmALMT1	Plasma membrane of mature root tissues	R-type NO3− > sulfate > Cl− selective anion channel Anion efflux	Undetermined	[167]
AtNPF2.5	Plasma membrane of root cortical cells	Low magnitude Cl− cell efflux	Cl− exclusion through excretion to the rhizosphere Salinity tolerance?	[153]
AtSLAH3	Plasma membrane of guard cells Plasma membrane of Xylem-pole pericycle cells	S-type NO3− > Cl− selective anion channel High magnitude NO3− and Cl− cell efflux	Stomatal closure Root xylem loading of NO3− and Cl−	[45,176]
AtSLAH1	Plasma membrane of Xylem-pole pericycle cells	Electrically silent S-type anion channel Regulation of SLAH3 activity	Regulation of root-to-shoot Cl− conductance	[176,184]
AtNPF2.4	Plasma membrane of root stelar cells	Low magnitude Cl− cell efflux	Root-to-shoot Cl− translocation	[152]
AtALMT12	Plasma membrane of guard cells Root vasculature	R-type malate-activated NO3− > Cl− selective anion channel Outward NO3− and Cl− cell efflux	Stomatal closure Undetermined root function	[185,186]
AtCCC	Golgi and trans-Golgi network Plasma membrane? Root vasculature and many other tissues	Cl−-dependent Na+/K+ Cotransporter	Directly or indirectly affects root-to-shoot Cl− distribution Developmental and other undetermined functions	[56,122]
OsCCC1	Plasma membrane of multiple root and shoot cell types	Cl−-dependent Na+/K+ Cotransporter	Regulation of Cl−, Na+ and K+ homeostasis and cell osmotic potential	[57]
AtALMT9	Tonoplast of guard cells Root and shoot vasculature	R-type malate-activated vacuolar Cl− channel Cl− homeostasis during early salinity stress	Required for stomatal opening Regulation of ion xylem loading	[69,70]
AtCLCc	Tonoplast of root, pollen grain and guard cells	vacuolar Cl− compartmentalization	Stomatal function Regulations of shoot Cl− accumulation? Salinity tolerance	[198,199]
AtCLCg	Tonoplast of mesophyll cells vascular tissue	vacuolar Cl− compartmentalization	Regulations of shoot Cl− accumulation? Salinity tolerance	[201]
GmCLC1	Tonoplast	vacuolar pH-dependent Cl− compartmentalization H+/Cl− Antiporter	Root Cl− sequestering Regulations of shoot Cl− accumulation Salinity tolerance	[194,195,196]
GsCLC-c2	Tonoplast	vacuolar channel with Cl− > NO3− affinity Cl− and NO3− compartmentalization	Regulations of shoot Cl− accumulation? Salinity tolerance	[200]
GmSALT3/CHX1	Endoplasmic reticulum of root vasculature-associated cells	Unknown	Regulations of shoot Cl− accumulation? Salinity tolerance	[210,211,212]