Table 1.

Genes encoding Natural Resistance-Associated Macrophage Proteins (Nramp) for Cd transport in plants.

Plant Species	Genes	Expression Sites	Subcellular Location	Function	References
Arabidopsis thaliana	AtNramp1	Roots	Plasma membrane	-	[25]
	AtNramp3	Roots and aerial parts	Tonoplast	Cd transport	[25,26,27,28]
	AtNramp4	Roots and aerial parts	Tonoplast	Cd transport	[25,28,29]
	AtNramp6	Seed embryo, lateral roots and young leaves	Golgi/trans-Golgi network	Cd transport	[30]
Oryza sativa L.	OsNramp1	Roots and leaves	Plasma membrane	Cd uptake and translocation	[31,32,33]
	OsNramp2	Embryo of germinating seeds, roots, leaf sheaths and leaf blades	Tonoplast	Cd retranslocation	[34,35]
	OsNramp5	Roots epidermis, exodermis, outer layers of cortex and tissues around xylem	Plasma membrane	Cd uptake	[36,37,38,39]
Triticum polonicum L.	TpNramp3	leaf blades and roots at the jointing and booting stages, first nodes at the grain filling stage	Plasma membrane	Cd accumulation	[40]
	TpNramp5	Roots and basal stems of DPW	Plasma membrane	Cd accumulation	[41]
Triticum turgidum L.	TtNramp6	Roots	Plasma membrane	Cd accumulation	[42]
Hordeum vulgare	HvNramp5	Roots	Plasma membrane	Cd uptake	[43]
Fagopyrum esculentum Moench	FeNramp5	Roots	Plasma membrane	Cd uptake	[44]
Brassica napus	BnNramp1b	Vegetative tissue, flowers and siliques	-	-	[45]
Brassica rapa L.	BcNramp1	Roots	Plasma membrane	Cd uptake	[46]
Noccaea caerulescens (Thlaspi caeulescens)	NcNramp1	Roots and shoots	Plasma membrane	-	[47]
	TcNramp3	-	Tonoplast	-	[48,49]
	TcNramp4	-	Tonoplast	-	[48]
Sedum alfredii Hance	SaNramp1	Young tissues of the shoots	Plasma membrane	Cd translocation	[50]
	SaNramp3	-	-	Cd translocation	[51]
	SaNramp6	Roots	Plasma membrane	Cd uptake or translocation	[52,53]
Malus xiaojinensis	MxNramp1	Roots	Plasma membrane	Cd uptake and translocation	[54]
	MxNramp3	Roots and leaves	Tonoplast	Cd uptake and translocation	[54]
Malus hupehensis	MhNramp1	Roots	Cell membrane	Cd uptake	[55]
Spirodela polyrhiza	SpNramp1	-	Plasma membrane	Cd accumulation	[56]
	SpNramp2	-	Plasma membrane	Cd accumulation	[56]
	SpNramp3	-	Plasma membrane	-	[56]
Crotalaria juncea	CjNramp1	Leaves, stems, and roots	Plasma membrane	Cd uptake and translocation	[57]
Nicotiana tabacum	NtNRAMP1	Roots	-	Cd uptake	[58]
	NtNRAMP3	Conductive tissue of leaves	Tonoplast	Cd efflux	[59]