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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

Thermal properties of starch.(A-C) Comparison of starch thermal properties, including onset temperature, maximum temperature and enthalpy, between W64Ao2 and K0326Y. Significant level indicated by asterisks at p<0.05 by two-tailed t test (D-F) Comparison of the starch thermal properties among RILs. For parental lines, each column represents mean thermal property values of three independent ears of corresponding lines; and for RILs, each column represents mean thermal property values of all RILs of the corresponding genotype with three independent ears for each individual RIL. The letters above each column represent statistically significant differences among the lines for p<0.05 by pairwise two-tailed t-test. Columns sharing the same letter are not significantly different from one another. The error bars represent standard error.
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pone.0130856.g003: Thermal properties of starch.(A-C) Comparison of starch thermal properties, including onset temperature, maximum temperature and enthalpy, between W64Ao2 and K0326Y. Significant level indicated by asterisks at p<0.05 by two-tailed t test (D-F) Comparison of the starch thermal properties among RILs. For parental lines, each column represents mean thermal property values of three independent ears of corresponding lines; and for RILs, each column represents mean thermal property values of all RILs of the corresponding genotype with three independent ears for each individual RIL. The letters above each column represent statistically significant differences among the lines for p<0.05 by pairwise two-tailed t-test. Columns sharing the same letter are not significantly different from one another. The error bars represent standard error.

Mentions: DSC analysis of the parental lines W64Ao2 and K0326Y showed that there was no significant difference between o2 and QPM parental lines for onset and maximum endotherm, but K0326Y had significantly lower enthalpy (Fig 3A–3C), indicating that QPM starch granules have lower overall crystallinity. In addition, DSC analysis of RILs with varying vitreousness showed that the thermal properties of the starch were influenced by both pullulanase and SSIII (Fig 3D–3F). The onset temperature and maximum temperature of the RILs homozygous for QPM-derived Zpu1 alleles and W64Ao2-derived SSIII alleles (Q-W) were significantly higher than others (Fig 3D and 3E). Also, among the RILs with homozygous QPM-derived Zpu1 alleles, those homozygous for QPM-derived SSIII alleles (Q-Q) showed significantly lower onset and maximum temperature than those homozygous for W64Ao2-derived SSIII alleles (Q-W). Among the RILs homozygous for the W64Ao2-derived Zpu1 alleles, those with homozygous QPM-derived SSIII alleles (W-Q) showed significantly higher enthalpy than those homozygous for the W64Ao2-derived SSIII alleles (W-W). Likewise, among the RILs homozygous for the QPM-derived SSIII alleles, those homozygous for the QPM-derived Zpu1 alleles (Q-Q) had significantly lower enthalpy than those with W64Ao2-derived Zpu1 alleles (W-Q). These data suggest that pullulanase and SSIII could influence the activity of each other resulting in different glucan chain length and crystallinity of starch granules, which in turn influence the starch thermal properties and starch granule structure.


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)

Thermal properties of starch.(A-C) Comparison of starch thermal properties, including onset temperature, maximum temperature and enthalpy, between W64Ao2 and K0326Y. Significant level indicated by asterisks at p<0.05 by two-tailed t test (D-F) Comparison of the starch thermal properties among RILs. For parental lines, each column represents mean thermal property values of three independent ears of corresponding lines; and for RILs, each column represents mean thermal property values of all RILs of the corresponding genotype with three independent ears for each individual RIL. The letters above each column represent statistically significant differences among the lines for p<0.05 by pairwise two-tailed t-test. Columns sharing the same letter are not significantly different from one another. The error bars represent standard error.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0130856.g003: Thermal properties of starch.(A-C) Comparison of starch thermal properties, including onset temperature, maximum temperature and enthalpy, between W64Ao2 and K0326Y. Significant level indicated by asterisks at p<0.05 by two-tailed t test (D-F) Comparison of the starch thermal properties among RILs. For parental lines, each column represents mean thermal property values of three independent ears of corresponding lines; and for RILs, each column represents mean thermal property values of all RILs of the corresponding genotype with three independent ears for each individual RIL. The letters above each column represent statistically significant differences among the lines for p<0.05 by pairwise two-tailed t-test. Columns sharing the same letter are not significantly different from one another. The error bars represent standard error.
Mentions: DSC analysis of the parental lines W64Ao2 and K0326Y showed that there was no significant difference between o2 and QPM parental lines for onset and maximum endotherm, but K0326Y had significantly lower enthalpy (Fig 3A–3C), indicating that QPM starch granules have lower overall crystallinity. In addition, DSC analysis of RILs with varying vitreousness showed that the thermal properties of the starch were influenced by both pullulanase and SSIII (Fig 3D–3F). The onset temperature and maximum temperature of the RILs homozygous for QPM-derived Zpu1 alleles and W64Ao2-derived SSIII alleles (Q-W) were significantly higher than others (Fig 3D and 3E). Also, among the RILs with homozygous QPM-derived Zpu1 alleles, those homozygous for QPM-derived SSIII alleles (Q-Q) showed significantly lower onset and maximum temperature than those homozygous for W64Ao2-derived SSIII alleles (Q-W). Among the RILs homozygous for the W64Ao2-derived Zpu1 alleles, those with homozygous QPM-derived SSIII alleles (W-Q) showed significantly higher enthalpy than those homozygous for the W64Ao2-derived SSIII alleles (W-W). Likewise, among the RILs homozygous for the QPM-derived SSIII alleles, those homozygous for the QPM-derived Zpu1 alleles (Q-Q) had significantly lower enthalpy than those with W64Ao2-derived Zpu1 alleles (W-Q). These data suggest that pullulanase and SSIII could influence the activity of each other resulting in different glucan chain length and crystallinity of starch granules, which in turn influence the starch thermal properties and starch granule structure.

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