Comparison of anthocyanin and polyphenolics in purple sweetpotato (Ipomoea batatas Lam.) grown in different locations in Japan

Figures & data

Figure 1. Structures of the sweetpotato anthocyanins (a) and polyphenolics (caffeoylquinic acids) (b). Glu, Glucopyranoside; HB, p-Hydroxybenzoic acid; Cf, Caffeic acid; Fr; Ferulic acid.

Table 1. Weather data during cultivation in 2015 and 2016

		Precipitation (mm)		Sunshine duration (h)		Mean temperature (^oC)		Maximam temperature (^oC)		Minimum temperature (^oC)		Accumulated temperature (^oC)
Location	Month	2015	2016	2015	2016	2015	2016	2015	2016	2015	2016	2015	2016
I	Jun	29	180	126	109	15	14	20	18	10	10	378	394
	Jul	56	135	188	91	20	18	27	23	15	15	627	558
	Aug	119	419	118	126	20	22	25	27	16	18	606	676
	Sep	112	138	155	120	16	17	21	22	11	12	471	500
	Oct	8	14	32	31	12	14	18	21	5	8	61	57
	Sum/Ave^1	323	884	618	478	16	17	22	22	11	13	2,144	2,185
II	May	30	99	67	113	21	21	27	27	15	17	228	160
	Jun	1095	855	61	80	22	23	25	27	19	20	644	697
	Jul	567	648	123	165	25	27	30	32	22	23	786	834
	Aug	378	117	182	223	27	28	32	34	23	24	828	860
	Sep	161	531	146	129	23	26	29	31	20	22	700	767
	Oct	12	34	64	21	20	26	27	31	14	23	158	130
	Sum/Ave^1	2,241	2,282	641	730	23	25	28	30	19	22	3,344	3,448

The data are expressed as the mean of each month during cultivation. ¹ Sum of the data of precipitation, sunshine duration and accumulated temperature or average of the data of mean, maximum and minimum temperatures of each month. Location I, 143°04E/42°92ʹN; location II, 131°03ʹE/31°72ʹN.

Table 2. Total anthocyanin, cyanidin, peonidin content and peonidin/cyanidin ratio in individual varieties cultivated in two locations in 2015 and 2016

Variety	Location	Total anthocyanin			Cyanidin			Peonidin			Peonidin/Cyanidin
		Year			Year			Year			Year
		2015	2016	Mean	2015	2016	Mean	2015	2016	Mean	2015	2016	Mean
MM	I	523	277	400 ^a	131	64	98 ^a	392	212	302 ^b	3.0	3.3	3.1 ^b
	II	600	211	406 ^a	124	47	86 ^b	476	164	320 ^a	3.9	3.5	3.7 ^a
	Mean	562^a	244^b		128^a	56 ^b		434 ^a	188 ^b		3.4 ^a	3.4 ^a
PSL	I	262	150	210 ^a	93	49	75 ^a	169	101	142 ^a	1.8	2.1	1.3 ^b
	II	204	66	135 ^b	49	28	39 ^b	155	39	97 ^b	3.1	1.4	2.3 ^a
	Mean	239 ^a	108 ^b		75 ^a	38 ^b		163 ^a	70 ^b		2.4 ^a	1.7 ^b
AKM	I	903	702	802 ^a	516	319	418 ^a	386	382	384 ^a	0.8	1.2	1.0 ^b
	II	597	283	440 ^b	264	118	191 ^b	333	166	250 ^b	1.3	1.4	1.3 ^a
	Mean	750 ^a	493 ^b		390 ^a	218 ^b		360 ^a	274 ^b		1.0 ^b	1.3 ^a
Three-way ANOVA
Location			**			**			**			**
Variety			**			**			**			**
Year			**			**			**			**
Location x Variety			**			**			**			**
Location x Year			**			**			**			**
Variety x Year			**			**			**			**
Location x Variety x Year			**			**			**			**

Cyanidin: sum of the contents of YGM 1a, 1b, 2 and 3. Peonidin: sum of the contents of YGM 4b, 5a, 5b and 6. Comparisons of the contents of total anthocyanin, cyanidin, and peonidin, and peonidin/cyanidin in each variety among locations and years were performed by ANOVA and multiple regression analysis was performed by Tukey’s test. * and ** indicate significance at the 5% and 1% levels, respectively. Different letters indicate statistically significant differences among locations and years in each variety at P < 0.01.

Figure 2. Representative HPLC chromatogram of sweetpotato YGM-anthocyanins (a) and polyphenolics (b). A: Indicated numbers means YGM-anthocyanins. B: 1, ChA; 2, CA; 3, 3,4-diCQA; 4, 3,5-diCQA; 5, 4,5-diCQA.

Table 3. The contents and proportions of total polyphenolics and caffeoylquinic acids in individual varieties cultivated in two locations in 2015 and 2016

		Total polyphenolics			ChA			3,4-diCQA			3,5-diCQA			4,5-diCQA
		Year			Year			Year			Year			Year
Variety	Location	2015	2016	Mean	2015	2016	Mean	2015	2016	Mean	2015	2016	Mean	2015	2016	Mean
MM	I	573	358	466 ^a	315 (54.9)	191 (53.2)	253 ^a (54.1^a)	17 (3.0)	12 (3.2)	15 ^b (3.1 ^b)	235 (41.0)	152 (42.5)	193 ^a (41.7 ^a)	6.0 (1.0)	3.5 (1.0)	4.7 ^b (1.0 ^b)
	II	213	67	140 ^b	103 (48.3)	19 (28.9)	61 ^b (38.6 ^b)	20 (9.3)	14 (21.0)	17 ^a (15.1^a)	84 (38.9)	28 (41.8)	56 ^b (40.3 ^a)	7.0 (3.3)	5.1 (7.7)	6.1 ^a (5.5 ^a)
	Mean	393 ^a	213 ^b		208 ^a (51.6 ^a)	105 ^b (41.1 ^b)		19 ^a (6.2^b)	13 ^b (12.1 ^a)		159 ^a (39.9 ^a)	90 ^b (42.1 ^a)		6.5 ^a (2.2 ^b)	4.3 ^b (4.3 ^a)
PSL	I	305	203	254 ^a	125 (40.7)	90 (44.3)	107 ^a (42.5 ^b)	2.8 (0.9)	1.8 (0.9)	2.3 ^a (0.9 ^b)	174 (56.9)	109 (53.7)	141 ^a (55.3 ^a)	3.6 (1.2)	1.9 (0.9)	2.8 ^a (1.1 ^b)
	II	212	15	114 ^b	88 (41.4)	7.5 (48.8)	48 ^b (45.1 ^a)	2.1 (1.0)	0.9 (5.8)	1.5 ^b (3.4 ^a)	119 (56.2)	6.2 (40.0)	63 ^b (48.1 ^b)	2.8 (1.3)	0.3 (1.7)	1.6 ^b (1.5 ^a)
	Mean	259 ^a	109 ^b		106 ^a (41.1 ^b)	49 ^b (46.5 ^a)		2.5 ^a (0.9 ^b)	1.4 ^b (3.3 ^a)		146.4 ^a (56.6 ^a)	57.6 ^b (46.8 ^b)		3.2 ^a (1.3 ^a)	1.1 ^b (1.3 ^a)
AKM	I	537	380	458 ^a	302 (56.3)	221 (58.1)	262 ^a (57.2 ^a)	4.3 (0.8)	5.0 (1.3)	4.7 ^a (1.1 ^b)	226 (42.1)	150 (39.5)	188 ^a (40.8 ^b)	3.9 (0.7)	3.2 (0.8)	3.5 ^a (0.8 ^b)
	II	103	20	61 ^b	45 (43.6)	7.6 (38.5)	26.3 ^b (41.1^b)	3.6 (3.5)	2.5 (13.0)	3.0 ^b (8.2 ^a)	50 (48.7)	7.5 (38.1)	29 ^b (43.4 ^a)	2.9 (2.9)	1.2 (6.0)	2.1 ^b (4.4 ^a)
	Mean	320 ^a	200 ^b		174 ^a (49.9 ^a)	114 ^b (48.3 ^a)		4.0 ^a (2.1 ^b)	3.8 ^a (7.1 ^a)		138 ^a (45.4 ^a)	79 ^b (38.8 ^b)		3.4 ^a (1.8 ^b)	2.2 ^b (3.4 ^a)
Three-way ANOVA
Location			**			** (**)			(**)			** (**)			** (**)
Variety			**			** (**)			** (**)			** (**)			** (**)
Year			**			** (**)			** (**)			** (**)			** (**)
Location x Variety			**			** (**)			** (**)			** (**)			** (**)
Location x Year						* (**)			(**)			(**)			* (**)
Variety x Year			**			** (**)			** (**)			** (**)			** (**)
Location x Variety x Year			**			** (**)			(**)			** (**)			** (**)

Relative amounts of individual caffeoylquinic acids (%) in each variety cultivated in each location are shown in parentheses. Comparisons of the contents and arcsine transformed proportions of ChA, 3,4-diCQA, 3,5-diCQA and 4,5-diCQA in each variety among locations and years were performed by ANOVA and multiple regression analysis was performed by Tukey’s test. CA contents and proportions are omitted from the table because the contents were insignificant level. * and ** indicate significance at the 5% and 1% levels, respectively. Different letters indicate statistically significant differences among locations and years in each variety at P < 0.01.