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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

Scanning electron microscopy of starch granules from parental lines and RILs.(A) Smooth starch granules in W64Ao2 endosperm with a little matrix surrounding them. (B) Contacts (arrows) and interconnections (asterisks) formed between adjacent starch granules in K0326Y endosperm. (C) Starch granules in the endosperm of the opaque RIL 217 showed similar smooth surface as in W64Ao2. (D) Starch granules in the endosperm of RIL 27 showed similar contact and interconnection structure as in K0326Y. (E-F) Starch granules in the endosperm of RIL 209 (E) and RIL 112 (F) showed similar smooth surface as in W64Ao2.
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pone.0130856.g005: Scanning electron microscopy of starch granules from parental lines and RILs.(A) Smooth starch granules in W64Ao2 endosperm with a little matrix surrounding them. (B) Contacts (arrows) and interconnections (asterisks) formed between adjacent starch granules in K0326Y endosperm. (C) Starch granules in the endosperm of the opaque RIL 217 showed similar smooth surface as in W64Ao2. (D) Starch granules in the endosperm of RIL 27 showed similar contact and interconnection structure as in K0326Y. (E-F) Starch granules in the endosperm of RIL 209 (E) and RIL 112 (F) showed similar smooth surface as in W64Ao2.

Mentions: Scanning electron microscopy was performed to analyze the gross structure and organization of starch granules in W64Ao2, K0326Y, RIL 217, RIL 27, RIL 209 and RIL 112 endosperms. The starch granules of W64Ao2 were smooth and separate, except for a small amount of matrix material surrounding them and had fairly uniform large size (Fig 5A), whereas there were many contacts (arrows) and interconnections (asterisks) forming between adjacent starch granules in K0326Y endosperm and the granules varied in size (Fig 5B). RIL 217 homozygous for the W64Ao2-derived Zpu1 alleles and homozygous for the QPM-derived SSIII alleles (W-Q) had opaque kernels, and had fewer and less extensive contacts between adjacent starch granules than K0326Y, but more material was present between the starch granules than in W64Ao2 or some of the other RILs (Fig 5C). In contrast, RIL 27 homozygous for the QPM-derived Zpu1 alleles and homozygous for the QPM-derived SSIII alleles (Q-Q) had vitreous kernels, and showed marked contacts and interconnections between starch granules (Fig 5D), similar to K0326Y. In addition, RIL 209 homozygous for the QPM-derived Zpu1 alleles and homozygous for the W64Ao2-derived SSIII alleles (Q-W) had opaque kernels, and showed smooth and separate starch granules like W64Ao2 but the starch granules varied in size like K0326Y (Fig 5E).Whereas RIL 112 homozygous for the W64Ao2-derived Zpu1 alleles and homozygous for the W64Ao2-derived SSIII alleles (W-W) had semi-vitreous kernels, but showed smooth and separate starch granules (Fig 5F) similar to opaque kernels.


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)

Scanning electron microscopy of starch granules from parental lines and RILs.(A) Smooth starch granules in W64Ao2 endosperm with a little matrix surrounding them. (B) Contacts (arrows) and interconnections (asterisks) formed between adjacent starch granules in K0326Y endosperm. (C) Starch granules in the endosperm of the opaque RIL 217 showed similar smooth surface as in W64Ao2. (D) Starch granules in the endosperm of RIL 27 showed similar contact and interconnection structure as in K0326Y. (E-F) Starch granules in the endosperm of RIL 209 (E) and RIL 112 (F) showed similar smooth surface as in W64Ao2.
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Related In: Results  -  Collection

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

pone.0130856.g005: Scanning electron microscopy of starch granules from parental lines and RILs.(A) Smooth starch granules in W64Ao2 endosperm with a little matrix surrounding them. (B) Contacts (arrows) and interconnections (asterisks) formed between adjacent starch granules in K0326Y endosperm. (C) Starch granules in the endosperm of the opaque RIL 217 showed similar smooth surface as in W64Ao2. (D) Starch granules in the endosperm of RIL 27 showed similar contact and interconnection structure as in K0326Y. (E-F) Starch granules in the endosperm of RIL 209 (E) and RIL 112 (F) showed similar smooth surface as in W64Ao2.
Mentions: Scanning electron microscopy was performed to analyze the gross structure and organization of starch granules in W64Ao2, K0326Y, RIL 217, RIL 27, RIL 209 and RIL 112 endosperms. The starch granules of W64Ao2 were smooth and separate, except for a small amount of matrix material surrounding them and had fairly uniform large size (Fig 5A), whereas there were many contacts (arrows) and interconnections (asterisks) forming between adjacent starch granules in K0326Y endosperm and the granules varied in size (Fig 5B). RIL 217 homozygous for the W64Ao2-derived Zpu1 alleles and homozygous for the QPM-derived SSIII alleles (W-Q) had opaque kernels, and had fewer and less extensive contacts between adjacent starch granules than K0326Y, but more material was present between the starch granules than in W64Ao2 or some of the other RILs (Fig 5C). In contrast, RIL 27 homozygous for the QPM-derived Zpu1 alleles and homozygous for the QPM-derived SSIII alleles (Q-Q) had vitreous kernels, and showed marked contacts and interconnections between starch granules (Fig 5D), similar to K0326Y. In addition, RIL 209 homozygous for the QPM-derived Zpu1 alleles and homozygous for the W64Ao2-derived SSIII alleles (Q-W) had opaque kernels, and showed smooth and separate starch granules like W64Ao2 but the starch granules varied in size like K0326Y (Fig 5E).Whereas RIL 112 homozygous for the W64Ao2-derived Zpu1 alleles and homozygous for the W64Ao2-derived SSIII alleles (W-W) had semi-vitreous kernels, but showed smooth and separate starch granules (Fig 5F) similar to opaque kernels.

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