Effects of different Wx alleles on amylopectin molecular structure and enzymatic hydrolysis properties of rice starch

Figures & data

Table 1. Single-segment substitution lines with different Wx alleles used in the present study.

SSSLs^a	Wx allele	Donor	Marker interval of substituted segments^b	Length (cM)^c	Amylose level (%)^d
W07-11-02-09-01	wx	Suyunuo	RM508---RM589–RM190---RM204	6.5	1.95
W12-09-28-10-18-10-04	Wx^t	IR58025B	RM170---RM190---RM587	2.2	10.23
W24-02-08-01-01-10-04	Wx^g1	Star bonnet 99	RM170---RM190---RM587	2.2	21.97
HJX74 (recipient)	Wx^g2				24.56
W04-10-02-07-10-03	Wx^g3	BG367	RM589---RM190---RM587	2.2	26.30

^aThe information for SSSLs was cited from Teng et al.^[9]

^bThe solid lines represent substituted segments, and both sides of dotted lines represent a possible interval of recombination.

^cLength of substituted chromosome segments in SSSLs: cM, centi-Morgan.

^dThese data were cited from Teng et al.^[7]

Table 2. Amylopectin chain length distribution of rice starches from single-segment substitution lines with different Wx alleles^a.

	Fraction (%)^b
Wx genotype	A (DP 6–12)	B1 (DP 13–24)	B2 (DP 25–36)	B3+ (DP ≥ 37)	ACL (DP)^c	(A+ B1)/(B2+ B3+)
wx	25.38 ± 0.13 c	47.39 ± 0.25 c	12.09 ± 0.23 a	15.13 ± 0.15 a	22.07 ± 0.09 a	2.67 ± 0.05 b
Wx^t	24.76 ± 0.10 b	46.68 ± 0.21 c	12.15 ± 0.09 a	16.41 ± 0.02 b	22.45 ± 0.42 a	2.50 ± 0.01 b
Wx^g1	24.62 ± 0.14 b	45.23 ± 0.35 b	12.44 ± 0.02 a	17.70 ± 0.47 c	23.34 ± 0.27 b	2.32 ± 0.05 a
Wx^g2	24.03 ± 0.03 a	45.67 ± 0.37 b	12.46 ± 0.12 a	17.83 ± 0.19 c	23.37 ± 0.14 b	2.30 ± 0.04 a
Wx^g3	25.24 ± 0.24 c	44.69 ± 0.23 a	12.34 ± 0.07 a	17.73 ± 0.06 c	23.39 ± 0.07 b	2.33 ± 0.01 a

^aData (mean±standard deviation) in the same column with different letters were significantly different (n = 2, P < 0.05).

^bFractions A, B1, B2 and B3₊ are the proportions of amylopectin branch chains of DP 6–12, DP 13–24, DP 25–36, and DP ≥ 37, respectively.

^cACL is the average chain length of amylopectin.

Figure 1. FACE chromatogram of amylopectin in endosperm from rice single-segment substitution lines with different Wx alleles. (a) Molar percentage distribution of isoamylase-debranched amylopectin and (b) chain length number distribution. All the chromatograms of branch chain length distribution of amylopectin were normalized in order to avoid the effect of different sample concentrations.

Table 3. Correlation coefficients between structural characteristics of starches from rice single-segment substitution lines with different Wx alleles^a.

Property	A (DP 6–12)	B1 (DP 13–24)	B2 (DP 25–36)	B3+ (DP≥37)	ACL	(A+ B1)/ (B2+ B3+)	AAC	RCD
B1 (DP 13–24)	0.254
B2 (DP 25–36)	−0.681	−0.826
B3+ (DP≥37)	−0.594	−0.928*	0.934*
ACL	−0.516	−0.952*	0.953*	0.984**
(A+ B1)/(B2+ B3+)	0.621	0.916*	−0.945*	−0.999**	−0.982**
AAC^b	−0.491	−0.958*	0.913*	0.984**	0.991**	−0.980**
RCD^b	0.431	0.977**	−0.883*	−0.979**	−0.982**	0.971**	−0.996**
IR^b	0.588	0.818	−0.886*	−0.901*	−0.874	0.908*	−0.831	0.833

^a* and ** indicated significance at the P< 0.05 and P< 0.01 levels, respectively (n=5). A, B1,B2 and B3₊ are the proportions of amylopectin branch chains of DP 6–12, DP 13–24, DP 25–36,and DP ≥ 37, respectively; ACL, average chain length of amylopectin; AAC, apparent amylose content; RCD, relative crystallinity degree; IR, intensity ratio of 1047/1022 cm⁻¹.

^bThese data were cited from Teng et al.^[7]

Figure 2. Hydrolysis properties of native starches from rice single-segment substitution lines with different Wx alleles. Vertical bars represent mean values ± standard deviations (n = 3). The hydrolysis degrees are expressed as the percentage of soluble carbohydrates released from native starches by PPA (a) and AAG (b).

Figure 3. Digestion properties of native starches from rice single-segment substitution lines with different Wx alleles. Vertical bars represent mean values ± standard deviations (n = 3). The digestion degrees are expressed as the percentage of glucose released from native starches by PPA and AAG.

Table 4. In vitro digestion properties of native starches from rice single-segment substitution lines with different Wx alleles^a.

Wx genotype	Starch nutritional fractions
	RDS (%)	SDS (%)	RS (%)
wx	22.13 ± 0.47 c	27.06 ± 0.74 d	50.81 ± 0.43 a
Wx^t	19.33 ± 0.48 b	26.33 ± 0.74 d	54.35 ± 0.62 b
Wx^g1	19.40 ± 0.32 b	19.89 ± 0.76 c	60.72 ± 0.71 c
Wx^g2	17.33 ± 0.34 a	17.84 ± 0.59 b	64.83 ± 0.57 e
Wx^g3	22.23 ± 0.55 c	15.26 ± 0.41 a	62.51 ± 0.58 d

^aData (mean±standard deviation) in the same column with different letters were significantly different (n = 3, P < 0.05). RDS, rapidly digestible starch; SDS, slowly digestible starch; RS, resistant starch.

Table 5. Correlation coefficients between molecular structure and enzyme hydrolysis of starches from rice single-segment substitution lines with different Wx alleles^a.

Properties	PPA	AAG	RDS	SDS	RS
A (DP 6–12)	0.665	0.667	0.981**	0.303	−0.619
B1 (DP 13–24)	0.834	0.859	0.105	0.944*	−0.878
B2 (DP 25–36)	−0.938*	−0.879*	−0.546	−0.842	0.944*
B3+ (DP≥37)	−0.944*	−0.978**	−0.466	−0.895*	0.963**
ACL	−0.950*	−0.934*	−0.367	−0.945*	0.972**
(A+ B1)/(B2+ B3+)	0.948*	0.978**	0.495	0.886*	−0.965**
AAC^b	−0.954*	−0.954*	−0.342	−0.959**	0.976**
RCD^b	0.924*	0.945*	0.285	0.955*	−0.952*
IR^b	0.755	0.840	0.508	0.678	−0.785

^a* and ** indicated significance at the P< 0.05 and P< 0.01 levels, respectively (n=5). A, B1, B2 and B3+ are the proportions of amylopectin branch chains of DP 6–12, DP 13–24, DP 25–36, and DP≥37, respectively; ACL, average chain length of amylopectin; AAC, apparent amylose content; RCD, relative crystallinity degree; IR, intensity ratio of 1047/1022 cm⁻¹; PPA, hydrolysis degree of PPA for 12 h; AAG, hydrolysis degree of AAG for 12 h; RDS, SDS, RS are the rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) of native starch, respectively.

^bThese data were cited from Teng et al.^[7]

Teng, B.; Zeng, R.; Wang, Y.; Liu, Z.; Zhang, Z.; Zhu, H.; Ding, X.; Li, W.; Zhang, G. Detection of Allelic Variation at the Wx Locus with Single-Segment Substitution Lines in Rice (Oryza Sativa L.). Mol. Breed. 2012, 30, 583–595. DOI: 10.1007/s11032-011-9647-x.

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Teng, B.; Zhang, Y.; Du, S.; Wu, J.; Li, Z.; Luo, Z.; Yang, J. Crystalline, Thermal and Swelling Properties of Starches from Single-Segment Substitution Lines with Different Wx Alleles in Rice (Oryza Sativa L.). J. Sci. Food Agric. 2017, 97, 108–114. DOI: 10.1002/jsfa.7693.

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