Table 1.

Influence of K supply on metabolite concentrations in flag leaves of barley during terminal drought stress.

		High K				Low K
		Control		Stress		Control		Stress
Pathways	Metabolite	HPR	LPR	HPR	LPR	HPR	LPR	HPR	LPR
Sugars	Glucose	3.0 c	3.3 c	12.2 b	19 a	3.4 c	5.4 c	19.4 a	23.2 a
	Fructose	6 b	7.4 b	22.9 a	23.7 a	6.4 b	8.7 b	22.9 a	30.7 a
	Sucrose	84.5 a	63.6 ab	49.2 ab	61 ab	55.1 ab	62.2 ab	38.8 b	35.8 b
	Starch	18.8 ab	16.9 bc	11.6 cd	4.4 ef	23.2 a	16.2 bcd	10.2 de	2.71 f
Sugar alcohol	Mannitol	33.6 cd	47.6 cd	85.38 bc	88.01 b	27.7 cd	11.7 d	153.9 a	94.68 b
Starch metabolism	Tre-6-P	0.8 cd	1.2 ab	1.2 bc	1.6 a	0.5 cd	0.7 cd	0.7 cd	0.4 d
	Sucrose-6-P	1.1 bc	1.3 abc	1.6 ab	1.9 a	1.2 bc	0.8 c	1.3 abc	0.8 c
	Hexose-6-P	73.5 ab	51.9 bc	73.8 ab	79.4 ab	80.7 a	25.2 cd	62.1 ab	21.2 d
	UDP-Glucose	39.1 a	40.9 a	32.1 ab	23.2 b	39.5 a	23.2 b	35.8 ab	19.8 b
	ADP-Glucose	0.2 a	0.06 bc	0.03 c	0.05 c	0.05 c	0.05 c	0.11 ab	0.04 bc
Calvin cycle	NADPH	1.2 bc	1.2 bc	1.4 bc	0.4 c	2.1 b	0.6 bc	3.5 a	0.7 bc
	ATP	19.2 a	14.5 abc	14.8 ab	1.8 d	8.6 bcd	3.9 cd	5.6 cd	2.1 d
Glycolysis	3PGA	515 a	417 ab	325 bc	46.8 e	214 cd	33.6 e	144 de	24.4 e
	PEP	19.2 ab	27.4 a	5.7 bc	0.2 c	19.2 ab	1.1 c	4.9 bc	0.8 c
TCA cycle	Oxoglutarate	301 abc	365 a	255 abc	167.4 cd	335 ab	224 bc	193 c	48.6 d
	Fumarate	4070 a	3189 bcd	3279 bc	2592 cd	3338 b	2510 de	3112 bcd	1704 e
	Citrate	13720 a	10108 b	6687 bc	5388 bc	3990 bc	3319 c	3892 bc	4710 bc
	Isocitrate	10055 a	11088 a	10685 a	9561 a	3440 b	4788 b	3379 b	3126 b
	Malate	12979 a	9743 b	6420 bc	6204 bc	5324 bc	2312 bc	4433 bc	4805 bc
Amino acids	Asn	36.3 cd	51.2 bc	23.4 d	68.9 a	51.2 bc	64.6 ab	54.2 ab	70.63 a
	Gln	58.2 b	84.1 b	74.4 b	128 b	131 b	132 b	64.7 b	380.76 a
	Gly	165 a	128 abc	90.7 c	159 ab	128 abc	119 bc	95 c	96.83 c
	Asp	915 a	1014 a	627 b	434 bcd	518 bc	457 bcd	363 cd	221 d
	Glu	6789 a	3009 b	3939 b	4893 ab	3770 b	3625 b	3698 b	3827 b
	Pro	13.2 c	14.7 c	12.5 c	13.8 c	18.9 c	59.3 a	33 b	16.17 c
	Phe	34.8 d	29.9 d	28.3 d	42.7 d	59.8 c	76.2 b	37.9 d	122.4 a

Concentrations of soluble and insoluble sugars, sugar alcohols, amino acids, and primary metabolites were measured in flag leaves of the lines HPR and LPR. Plants were pre-cultured under sufficient water supply (control) or water limitation (stress) and under low or high K supply. Flag leaves from 12 weeks-old plants were harvested 12 days after imposing drought stress. Bars indicate mean ± SD. Different letters denote significant differences according to 3-way ANOVA and Tukey’s test (p < 0.05; n = 4–6). Tre-6-P, trehalose-6-phosphate; Sucrose-6-P, sucrose-6-phosphate; Hexose-6-P, hexose-6-phosphate; ADP-Glc, ADP-glucose; 3PGA, 3 phosphpoglycerate; PEP, phosphoenolpyruvate; UDP-Glc, UDP-glucose; NADPH, nicotinamide adenine dinucleotide phosphate; ATP, adenosine triphosphate; Asn, asparagine; Gln, glutamine; Gly, glycine; Asp, aspartate; Glu, glutamate; GABA, gamma aminobutyric acid; Pro, proline; Phe, phenylalanine.