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Pullulanase and Starch Synthase III Are Associated with Formation of Vitreous Endosperm in Quality Protein Maize.

Wu H, Clay K, Thompson SS, Hennen-Bierwagen TA, Andrews BJ, Zechmann B, Gibbon BC - PLoS ONE (2015)

Bottom Line: Analysis of recombinant inbred lines derived from a cross of W64Ao2 and K0326Y revealed that pullulanase activity had significant positive correlation with kernel vitreousness.We also found that decreased Starch Synthase III abundance may decrease the pullulanase activity and average glucan chain length given the same Zpu1 genotype.Therefore, Starch Synthase III could indirectly influence the kernel vitreousness by affecting pullulanase activity and coordinating with pullulanase to alter the glucan chain length distribution of amylopectin, resulting in different starch structural properties.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Baylor University, Waco, Texas, 76798, United States of America.

ABSTRACT
The opaque-2 (o2) mutation of maize increases lysine content, but the low seed density and soft texture of this type of mutant are undesirable. Lines with modifiers of the soft kernel phenotype (mo2) called "Quality Protein Maize" (QPM) have high lysine and kernel phenotypes similar to normal maize. Prior research indicated that the formation of vitreous endosperm in QPM might involve changes in starch granule structure. In this study, we focused on analysis of two starch biosynthetic enzymes that may influence kernel vitreousness. Analysis of recombinant inbred lines derived from a cross of W64Ao2 and K0326Y revealed that pullulanase activity had significant positive correlation with kernel vitreousness. We also found that decreased Starch Synthase III abundance may decrease the pullulanase activity and average glucan chain length given the same Zpu1 genotype. Therefore, Starch Synthase III could indirectly influence the kernel vitreousness by affecting pullulanase activity and coordinating with pullulanase to alter the glucan chain length distribution of amylopectin, resulting in different starch structural properties. The glucan chain length distribution had strong positive correlation with the polydispersity index of glucan chains, which was positively associated with the kernel vitreousness based on nonlinear regression analysis. Therefore, we propose that pullulanase and Starch Synthase III are two important factors responsible for the formation of the vitreous phenotype of QPM endosperms.

No MeSH data available.


Related in: MedlinePlus

Average glucan chain length and polydispersity index (PDI).(A) Comparison of the average glucan chain length among RILs. Each column contains multiple lines homozygous for the parental alleles (W64Ao2 or QPM) of Zpu1 or SSIII. Each column represents mean glucan chain length of all RILs of the corresponding genotype with three independent ears of each individual RIL. (B) Positive correlation between average glucan chain length and PDI. The correlations are significant, tested by ANOVA of the slope at p<0.05. Each data point represents mean glucan chain length of three independent ears of each individual RIL. (C) Comparison of PDI between parental lines (W64A+, W64Ao2 and K0326Y). Each column represents the mean PDI value of three independent ears of corresponding lines. The letters above each column of (A) and (C) represent statistically significant differences among the lines for p<0.05 by each pair t test. Columns sharing the same letter are not significantly different from one another. The error bars represent corresponding standard error. (D) Nonlinear regression analysis between PDI and kernel vitreousness among RILs, test statistics are listed below. The relationship was significantly positive, because 0 was excluded from the 95% confidence interval of Growth Rate, indicating that the Growth Rate was greater than 0 at p-value = 0.05 level. Each data point represents mean PDI of three independent ears of each individual RIL. (E-G) Glucan chain length distribution between opaque lines (dash curves) and vitreous lines (solid curves).
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pone.0130856.g004: Average glucan chain length and polydispersity index (PDI).(A) Comparison of the average glucan chain length among RILs. Each column contains multiple lines homozygous for the parental alleles (W64Ao2 or QPM) of Zpu1 or SSIII. Each column represents mean glucan chain length of all RILs of the corresponding genotype with three independent ears of each individual RIL. (B) Positive correlation between average glucan chain length and PDI. The correlations are significant, tested by ANOVA of the slope at p<0.05. Each data point represents mean glucan chain length of three independent ears of each individual RIL. (C) Comparison of PDI between parental lines (W64A+, W64Ao2 and K0326Y). Each column represents the mean PDI value of three independent ears of corresponding lines. The letters above each column of (A) and (C) represent statistically significant differences among the lines for p<0.05 by each pair t test. Columns sharing the same letter are not significantly different from one another. The error bars represent corresponding standard error. (D) Nonlinear regression analysis between PDI and kernel vitreousness among RILs, test statistics are listed below. The relationship was significantly positive, because 0 was excluded from the 95% confidence interval of Growth Rate, indicating that the Growth Rate was greater than 0 at p-value = 0.05 level. Each data point represents mean PDI of three independent ears of each individual RIL. (E-G) Glucan chain length distribution between opaque lines (dash curves) and vitreous lines (solid curves).

Mentions: In order to understand what factors more directly influence the kernel vitreousness, the glucan chain length distribution of debranched amylopectin from the RIL populations was measured via fluorescence-assisted capillary electrophoresis (FACE). The results showed that the average degree of polymerization (DP; the number of α-D-glucopyranosyl units in glucan chains) was affected by both pullulanase and SSIII. The RILs homozygous for both W64Ao2-derived Zpu1 alleles and QPM-derived SSIII alleles (W-Q) showed the highest average glucan chain length among all selected RIL samples. Also, among the RILs homozygous for W64Ao2-derived Zpu1 alleles, those homozygous for W64Ao2-derived SSIII alleles (W-W) showed significant lower average glucan chain length than those homozygous for QPM-derived SSIII alleles (W-Q). Among the RILs homozygous for QPM-derived SSIII alleles, those homozygous for W64Ao2-derived Zpu1 alleles (W-Q) showed significantly higher average glucan chain length than those homozygous for QPM-derived Zpu1 alleles (Q-Q or Q-W) (Fig 4A). The average glucan chain length among those four types of RILs had similar trend to their enthalpy values (Fig 3F), indicating the glucan chain length could influence the crystallinity of starch granule, which in turn affects the enthalpy change during gelatinization.


Pullulanase and Starch Synthase III Are Associated with Formation of Vitreous Endosperm in Quality Protein Maize.

Wu H, Clay K, Thompson SS, Hennen-Bierwagen TA, Andrews BJ, Zechmann B, Gibbon BC - PLoS ONE (2015)

Average glucan chain length and polydispersity index (PDI).(A) Comparison of the average glucan chain length among RILs. Each column contains multiple lines homozygous for the parental alleles (W64Ao2 or QPM) of Zpu1 or SSIII. Each column represents mean glucan chain length of all RILs of the corresponding genotype with three independent ears of each individual RIL. (B) Positive correlation between average glucan chain length and PDI. The correlations are significant, tested by ANOVA of the slope at p<0.05. Each data point represents mean glucan chain length of three independent ears of each individual RIL. (C) Comparison of PDI between parental lines (W64A+, W64Ao2 and K0326Y). Each column represents the mean PDI value of three independent ears of corresponding lines. The letters above each column of (A) and (C) represent statistically significant differences among the lines for p<0.05 by each pair t test. Columns sharing the same letter are not significantly different from one another. The error bars represent corresponding standard error. (D) Nonlinear regression analysis between PDI and kernel vitreousness among RILs, test statistics are listed below. The relationship was significantly positive, because 0 was excluded from the 95% confidence interval of Growth Rate, indicating that the Growth Rate was greater than 0 at p-value = 0.05 level. Each data point represents mean PDI of three independent ears of each individual RIL. (E-G) Glucan chain length distribution between opaque lines (dash curves) and vitreous lines (solid curves).
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4482715&req=5

pone.0130856.g004: Average glucan chain length and polydispersity index (PDI).(A) Comparison of the average glucan chain length among RILs. Each column contains multiple lines homozygous for the parental alleles (W64Ao2 or QPM) of Zpu1 or SSIII. Each column represents mean glucan chain length of all RILs of the corresponding genotype with three independent ears of each individual RIL. (B) Positive correlation between average glucan chain length and PDI. The correlations are significant, tested by ANOVA of the slope at p<0.05. Each data point represents mean glucan chain length of three independent ears of each individual RIL. (C) Comparison of PDI between parental lines (W64A+, W64Ao2 and K0326Y). Each column represents the mean PDI value of three independent ears of corresponding lines. The letters above each column of (A) and (C) represent statistically significant differences among the lines for p<0.05 by each pair t test. Columns sharing the same letter are not significantly different from one another. The error bars represent corresponding standard error. (D) Nonlinear regression analysis between PDI and kernel vitreousness among RILs, test statistics are listed below. The relationship was significantly positive, because 0 was excluded from the 95% confidence interval of Growth Rate, indicating that the Growth Rate was greater than 0 at p-value = 0.05 level. Each data point represents mean PDI of three independent ears of each individual RIL. (E-G) Glucan chain length distribution between opaque lines (dash curves) and vitreous lines (solid curves).
Mentions: In order to understand what factors more directly influence the kernel vitreousness, the glucan chain length distribution of debranched amylopectin from the RIL populations was measured via fluorescence-assisted capillary electrophoresis (FACE). The results showed that the average degree of polymerization (DP; the number of α-D-glucopyranosyl units in glucan chains) was affected by both pullulanase and SSIII. The RILs homozygous for both W64Ao2-derived Zpu1 alleles and QPM-derived SSIII alleles (W-Q) showed the highest average glucan chain length among all selected RIL samples. Also, among the RILs homozygous for W64Ao2-derived Zpu1 alleles, those homozygous for W64Ao2-derived SSIII alleles (W-W) showed significant lower average glucan chain length than those homozygous for QPM-derived SSIII alleles (W-Q). Among the RILs homozygous for QPM-derived SSIII alleles, those homozygous for W64Ao2-derived Zpu1 alleles (W-Q) showed significantly higher average glucan chain length than those homozygous for QPM-derived Zpu1 alleles (Q-Q or Q-W) (Fig 4A). The average glucan chain length among those four types of RILs had similar trend to their enthalpy values (Fig 3F), indicating the glucan chain length could influence the crystallinity of starch granule, which in turn affects the enthalpy change during gelatinization.

Bottom Line: Analysis of recombinant inbred lines derived from a cross of W64Ao2 and K0326Y revealed that pullulanase activity had significant positive correlation with kernel vitreousness.We also found that decreased Starch Synthase III abundance may decrease the pullulanase activity and average glucan chain length given the same Zpu1 genotype.Therefore, Starch Synthase III could indirectly influence the kernel vitreousness by affecting pullulanase activity and coordinating with pullulanase to alter the glucan chain length distribution of amylopectin, resulting in different starch structural properties.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Baylor University, Waco, Texas, 76798, United States of America.

ABSTRACT
The opaque-2 (o2) mutation of maize increases lysine content, but the low seed density and soft texture of this type of mutant are undesirable. Lines with modifiers of the soft kernel phenotype (mo2) called "Quality Protein Maize" (QPM) have high lysine and kernel phenotypes similar to normal maize. Prior research indicated that the formation of vitreous endosperm in QPM might involve changes in starch granule structure. In this study, we focused on analysis of two starch biosynthetic enzymes that may influence kernel vitreousness. Analysis of recombinant inbred lines derived from a cross of W64Ao2 and K0326Y revealed that pullulanase activity had significant positive correlation with kernel vitreousness. We also found that decreased Starch Synthase III abundance may decrease the pullulanase activity and average glucan chain length given the same Zpu1 genotype. Therefore, Starch Synthase III could indirectly influence the kernel vitreousness by affecting pullulanase activity and coordinating with pullulanase to alter the glucan chain length distribution of amylopectin, resulting in different starch structural properties. The glucan chain length distribution had strong positive correlation with the polydispersity index of glucan chains, which was positively associated with the kernel vitreousness based on nonlinear regression analysis. Therefore, we propose that pullulanase and Starch Synthase III are two important factors responsible for the formation of the vitreous phenotype of QPM endosperms.

No MeSH data available.


Related in: MedlinePlus