Table 1.

Localization and main functions of the products of GS1 genes in cereals.

Species	Genes	Principal Localization of Gene Products	Function	References
Oryza sativa	OsGS1;1	vascular tissue of mature leaves	grain filling	[75]
	OsGS1;2	leaves, stems, and roots	primary NH4+ assimilation	[78,79,82]
	OsGS1;3	spikelet	grain ripening and germination	[46,75]
Zea mays	ZmGln1;2	pedicel and pericarp	development of kernel	[83,84]
	ZmGln1;3	leaves, roots, and stems	development of cobs in relation to kernel number	[85]
	ZmGln1;4	leaves, roots, stems, and older leaves; bundle sheath cells	NH4+ reassimilation during protein degradation in senescing leaves; development of cobs in relation to kernel size	[86,87]
	ZmGln1;5	cortical tissue of seedling roots, vasculature of roots; seedling shoots and in stems	not reported	[85]
Hordeum vulgare	HvGS1;1	vascular tissues	N transport and remobilization	[88]
	HvGS1;2	mesophyll cells of leaves; cortex and pericycle of roots	primary N assimilation	[88]
	HvGS1;3	specifically expressed in grains; expressed in roots under high NH4+ fertilization	defense against NH4+ toxicity	[88]
Triticum aestivum	TaGS1;1	perifascicular sheath; mesophyll cells; chalaza and placentochalaza	cytoplasmic NH4+ assimilation	[40,89]
	TaGS1;2/GSr	vascular cells of leaves and roots; vascular bundle; chalaza and placentochalaza	N transport	[49,89]
	TaGS1;3/GSe	mesophyll cells; endosperm transfer cells; aleurone layer	cytoplasmic NH4+ assimilation; alleviating NH4+ toxicity; gluten synthesis	[89,90]