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Identification and characterization of the maize arogenate dehydrogenase gene family.

Holding DR, Meeley RB, Hazebroek J, Selinger D, Gruis F, Jung R, Larkins BA - J. Exp. Bot. (2010)

Bottom Line: In plants, the amino acids tyrosine and phenylalanine are synthesized from arogenate by arogenate dehydrogenase and arogenate dehydratase, respectively, with the relative flux to each being tightly controlled.A Mutator insertion at an equivalent position in AroDH-3, the most closely related family member to AroDH-1, is also associated with opaque endosperm and stunted vegetative growth phenotypes.Overlapping but differential expression patterns as well as subtle mutant effects on the accumulation of tyrosine and phenylalanine in endosperm, embryo, and leaf tissues suggest that the functional redundancy of this gene family provides metabolic plasticity for the synthesis of these important amino acids. mto140/arodh-1 seeds shows a general reduction in zein storage protein accumulation and an elevated lysine phenotype typical of other opaque endosperm mutants, but it is distinct because it does not result from quantitative or qualitative defects in the accumulation of specific zeins but rather from a disruption in amino acid biosynthesis.

View Article: PubMed Central - PubMed

Affiliation: Center for Plant Science Innovation, University of Nebraska, 1901 Vine St., Lincoln, NE 68588, USA. dholding2@unl.edu

ABSTRACT
In plants, the amino acids tyrosine and phenylalanine are synthesized from arogenate by arogenate dehydrogenase and arogenate dehydratase, respectively, with the relative flux to each being tightly controlled. Here the characterization of a maize opaque endosperm mutant (mto140), which also shows retarded vegetative growth, is described The opaque phenotype co-segregates with a Mutator transposon insertion in an arogenate dehydrogenase gene (zmAroDH-1) and this led to the characterization of the four-member family of maize arogenate dehydrogenase genes (zmAroDH-1-zmAroDH-4) which share highly similar sequences. A Mutator insertion at an equivalent position in AroDH-3, the most closely related family member to AroDH-1, is also associated with opaque endosperm and stunted vegetative growth phenotypes. Overlapping but differential expression patterns as well as subtle mutant effects on the accumulation of tyrosine and phenylalanine in endosperm, embryo, and leaf tissues suggest that the functional redundancy of this gene family provides metabolic plasticity for the synthesis of these important amino acids. mto140/arodh-1 seeds shows a general reduction in zein storage protein accumulation and an elevated lysine phenotype typical of other opaque endosperm mutants, but it is distinct because it does not result from quantitative or qualitative defects in the accumulation of specific zeins but rather from a disruption in amino acid biosynthesis.

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arodh-1 and arodh-3 mutant phenotypes. (A) Phenotype of greenhouse-grown wild-type and arodh-1 isogenic plants (left three, AroDH-1/AroDH-1; right three, arodh-1/arodh-1). (B) Endosperm phenotypes shown in cracked kernels (left, WT; centre, arodh-1; right, arodh-3). (C) Illuminated kernels from an AroDH-1 segregating ear shown on a light box (opaque kernels on the bottom row). (D) Illuminated kernels from an AroDH-3 segregating ear shown on a light box (opaque kernels on the bottom row). (E) SDS–PAGE separation of the zein fraction from vitreous and opaque kernels of an AroDH-1 segregating ear.
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fig2: arodh-1 and arodh-3 mutant phenotypes. (A) Phenotype of greenhouse-grown wild-type and arodh-1 isogenic plants (left three, AroDH-1/AroDH-1; right three, arodh-1/arodh-1). (B) Endosperm phenotypes shown in cracked kernels (left, WT; centre, arodh-1; right, arodh-3). (C) Illuminated kernels from an AroDH-1 segregating ear shown on a light box (opaque kernels on the bottom row). (D) Illuminated kernels from an AroDH-3 segregating ear shown on a light box (opaque kernels on the bottom row). (E) SDS–PAGE separation of the zein fraction from vitreous and opaque kernels of an AroDH-1 segregating ear.

Mentions: Mutator-tagged opaque 140 (mto140) was one of several opaque endosperm mutants identified during a screen of Pioneer Hi-Bred's TUSC (Bensen et al., 1995). The mutation was introgressed into W64A (BC6) at the University of Arizona. mto140 grows more slowly than wild-type plants in the greenhouse (Fig. 2A), and has severely retarded growth and reduced seed production under Arizona field conditions (data not shown). The mature kernel phenotype manifests a marked reduction in the thickness of the vitreous endosperm layer (Fig. 2B) and has a reduced capacity to transmit light (opacity), as shown in Fig. 2C. Like some opaque mutants, mto140 has reduced zein protein accumulation, but, unlike o2, it affects accumulation of all zein classes (Fig. 2E), perhaps being indicative of a general effect on protein synthesis. Similar to the opaque5 (o5) and opaque 9 (o9) mutants, mto140 expresses a viridescent seedling phenotype (data not shown).


Identification and characterization of the maize arogenate dehydrogenase gene family.

Holding DR, Meeley RB, Hazebroek J, Selinger D, Gruis F, Jung R, Larkins BA - J. Exp. Bot. (2010)

arodh-1 and arodh-3 mutant phenotypes. (A) Phenotype of greenhouse-grown wild-type and arodh-1 isogenic plants (left three, AroDH-1/AroDH-1; right three, arodh-1/arodh-1). (B) Endosperm phenotypes shown in cracked kernels (left, WT; centre, arodh-1; right, arodh-3). (C) Illuminated kernels from an AroDH-1 segregating ear shown on a light box (opaque kernels on the bottom row). (D) Illuminated kernels from an AroDH-3 segregating ear shown on a light box (opaque kernels on the bottom row). (E) SDS–PAGE separation of the zein fraction from vitreous and opaque kernels of an AroDH-1 segregating ear.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2921203&req=5

fig2: arodh-1 and arodh-3 mutant phenotypes. (A) Phenotype of greenhouse-grown wild-type and arodh-1 isogenic plants (left three, AroDH-1/AroDH-1; right three, arodh-1/arodh-1). (B) Endosperm phenotypes shown in cracked kernels (left, WT; centre, arodh-1; right, arodh-3). (C) Illuminated kernels from an AroDH-1 segregating ear shown on a light box (opaque kernels on the bottom row). (D) Illuminated kernels from an AroDH-3 segregating ear shown on a light box (opaque kernels on the bottom row). (E) SDS–PAGE separation of the zein fraction from vitreous and opaque kernels of an AroDH-1 segregating ear.
Mentions: Mutator-tagged opaque 140 (mto140) was one of several opaque endosperm mutants identified during a screen of Pioneer Hi-Bred's TUSC (Bensen et al., 1995). The mutation was introgressed into W64A (BC6) at the University of Arizona. mto140 grows more slowly than wild-type plants in the greenhouse (Fig. 2A), and has severely retarded growth and reduced seed production under Arizona field conditions (data not shown). The mature kernel phenotype manifests a marked reduction in the thickness of the vitreous endosperm layer (Fig. 2B) and has a reduced capacity to transmit light (opacity), as shown in Fig. 2C. Like some opaque mutants, mto140 has reduced zein protein accumulation, but, unlike o2, it affects accumulation of all zein classes (Fig. 2E), perhaps being indicative of a general effect on protein synthesis. Similar to the opaque5 (o5) and opaque 9 (o9) mutants, mto140 expresses a viridescent seedling phenotype (data not shown).

Bottom Line: In plants, the amino acids tyrosine and phenylalanine are synthesized from arogenate by arogenate dehydrogenase and arogenate dehydratase, respectively, with the relative flux to each being tightly controlled.A Mutator insertion at an equivalent position in AroDH-3, the most closely related family member to AroDH-1, is also associated with opaque endosperm and stunted vegetative growth phenotypes.Overlapping but differential expression patterns as well as subtle mutant effects on the accumulation of tyrosine and phenylalanine in endosperm, embryo, and leaf tissues suggest that the functional redundancy of this gene family provides metabolic plasticity for the synthesis of these important amino acids. mto140/arodh-1 seeds shows a general reduction in zein storage protein accumulation and an elevated lysine phenotype typical of other opaque endosperm mutants, but it is distinct because it does not result from quantitative or qualitative defects in the accumulation of specific zeins but rather from a disruption in amino acid biosynthesis.

View Article: PubMed Central - PubMed

Affiliation: Center for Plant Science Innovation, University of Nebraska, 1901 Vine St., Lincoln, NE 68588, USA. dholding2@unl.edu

ABSTRACT
In plants, the amino acids tyrosine and phenylalanine are synthesized from arogenate by arogenate dehydrogenase and arogenate dehydratase, respectively, with the relative flux to each being tightly controlled. Here the characterization of a maize opaque endosperm mutant (mto140), which also shows retarded vegetative growth, is described The opaque phenotype co-segregates with a Mutator transposon insertion in an arogenate dehydrogenase gene (zmAroDH-1) and this led to the characterization of the four-member family of maize arogenate dehydrogenase genes (zmAroDH-1-zmAroDH-4) which share highly similar sequences. A Mutator insertion at an equivalent position in AroDH-3, the most closely related family member to AroDH-1, is also associated with opaque endosperm and stunted vegetative growth phenotypes. Overlapping but differential expression patterns as well as subtle mutant effects on the accumulation of tyrosine and phenylalanine in endosperm, embryo, and leaf tissues suggest that the functional redundancy of this gene family provides metabolic plasticity for the synthesis of these important amino acids. mto140/arodh-1 seeds shows a general reduction in zein storage protein accumulation and an elevated lysine phenotype typical of other opaque endosperm mutants, but it is distinct because it does not result from quantitative or qualitative defects in the accumulation of specific zeins but rather from a disruption in amino acid biosynthesis.

Show MeSH
Related in: MedlinePlus