Starch Granule (Amyloplast) Development in Endosperm of Several Zea mays L. Genotypes Affecting Kernel Polysaccharides

Boyer, Charles D.; Daniels, Ralph; Shannon, Jack C.

doi:10.2307/2441875

Cited by 35 publications

(12 citation statements)

References 6 publications

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“…It is apparent that the normal starch molecular structure can build rigid starch granules, although the reduction of ISA1 activity leads to irregular and small granules (Fig. 8; Boyer et al ., 1977; Zeeman et al ., 1998; Burton et al ., 2002; Fujita et al ., 2003; Wong et al ., 2003; Utsumi et al ., 2011). In contrast, small particles are formed by phytoglycogen and elongated glycogen via recombinant amylosucrase (Fig.…”

Section: Discussionmentioning

confidence: 99%

Elongated phytoglycogen chain length in transgenic rice endosperm expressing active starch synthase IIa affects the altered solubility and crystallinity of the storage α-glucan

Fujita

Hanashiro

Suzuki

et al. 2012

Journal of Experimental Botany

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The relationship between the solubility, crystallinity, and length of the unit chains of plant storage α-glucan was investigated by manipulating the chain length of α-glucans accumulated in a rice mutant. Transgenic lines were produced by introducing a cDNA for starch synthase IIa (SSIIa) from an indica cultivar (SSIIa I, coding for active SSIIa) into an isoamylase1 (ISA1)-deficient mutant (isa1) that was derived from a japonica cultivar (bearing inactive SSIIa proteins). The water-soluble fraction accounted for >95% of the total α-glucan in the isa1 mutant, whereas it was only 35–70% in the transgenic SSIIa I /isa1 lines. Thus, the α-glucans from the SSIIa I /isa1 lines were fractionated into soluble and insoluble fractions prior to the following characterizations. X-ray diffraction analysis revealed a weak B-type crystallinity for the α-glucans of the insoluble fraction, while no crystallinity was confirmed for α-glucans in isa1. Concerning the degree of polymerization (DP) ≤30, the chain lengths of these α-glucans differed significantly in the order of SSIIa I /isa1 insoluble > SSIIa I /isa1 soluble > α-glucans in isa1. The amount of long chains with DP ≥33 was higher in the insoluble fraction α-glucans than in the other two α-glucans. No difference was observed in the chain length distributions of the β-amylase limit dextrins among these α-glucans. These results suggest that in the SSIIa I /isa1 transgenic lines, the unit chains of α-glucans were elongated by SSIIaI, whereas the expression of SSIIaI did not affect the branch positions. Thus, the observed insolubility and crystallinity of the insoluble fraction can be attributed to the elongated length of the outer chains due to SSIIaI.

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Section: Discussionmentioning

confidence: 99%

Elongated phytoglycogen chain length in transgenic rice endosperm expressing active starch synthase IIa affects the altered solubility and crystallinity of the storage α-glucan

Fujita

Hanashiro

Suzuki

et al. 2012

Journal of Experimental Botany

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“…Localized phytoglycogen and starch accumulation has been observed in the developing endosperm of isoamylase mutant of cereals (Boyer et al. , 1977; Burton et al.…”

Section: A Range Of Glucans Accumulates In Tissue‐specific Patternsmentioning

confidence: 99%

Arabidopsis mutants Atisa1 and Atisa2 have identical phenotypes and lack the same multimeric isoamylase, which influences the branch point distribution of amylopectin during starch synthesis

et al. 2005

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SummaryThe aim of this work was to evaluate the function of isoamylase in starch granule biosynthesis in Arabidopsis leaves. A reverse-genetic approach was used to knockout AtISA1, one of three genes in Arabidopsis encoding isoamylase-type debranching enzymes. The mutant (Atisa1-1) lacks functional AtISA1 transcript and the major isoamylase activity (detected by native gels) in crude extracts of leaves. The same activity is abolished by mutation at the DBE1 locus, which encodes a second isoamylase-type protein, AtISA2. This is consistent with the idea that ISA1 and ISA2 proteins are subunits of the same enzyme in vivo. Atisa1-1, Atisa2-1 (dbe1), and the Atisa1-1/Atisa2-1 double mutant all have identical phenotypes. Starch content is reduced compared with the wild type but substantial quantities of the soluble glucan phytoglycogen are produced. The amylopectin of the remaining starch and the phytoglycogen in the mutants are structurally related to each other and differ from wild-type amylopectin. Electron micrographs reveal that the phytoglycogen-accumulating phenotype is highly tissue-specific. Phytoglycogen accumulates primarily in the plastids of the palisade and spongy mesophyll cells. Remarkably, other cell types appear to accumulate only starch, which is normal in appearance but is altered in structure. As phytoglycogen accumulates during the day, its rate of accumulation decreases, its structure changes and intermediates of glucan breakdown accumulate, suggesting that degradation occurs simultaneously with synthesis. We conclude that the AtISA1/AtISA2 isoamylase influences glucan branching pattern, but that this may not be the primary determinant of partitioning between crystalline starch and soluble phytoglycogen.

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“…The maize amylose extender ( ae ) mutant, which is deficient in SBEIIb, has a profound effect on starch structure, leading to an increased amylose proportion and a reduced branching density of endosperm amylopectin [5,33-35]. More recently, studies of a maize sbe2a mutant showed that deficiency of the SBEIIa isoform decreased plant fitness and resulted in lower kernel yield, but there was minimal effect on kernel starch properties [11,36].…”

Section: Introductionmentioning

confidence: 99%

Deficiency of maize starch-branching enzyme i results in altered starch fine structure, decreased digestibility and reduced coleoptile growth during germination

et al. 2011

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BackgroundTwo distinct starch branching enzyme (SBE) isoforms predate the divergence of monocots and dicots and have been conserved in plants since then. This strongly suggests that both SBEI and SBEII provide unique selective advantages to plants. However, no phenotype for the SBEI mutation, sbe1a, had been previously observed. To explore this incongruity the objective of the present work was to characterize functional and molecular phenotypes of both sbe1a and wild-type (Wt) in the W64A maize inbred line.ResultsEndosperm starch granules from the sbe1a mutant were more resistant to digestion by pancreatic α-amylase, and the sbe1a mutant starch had an altered branching pattern for amylopectin and amylose. When kernels were germinated, the sbe1a mutant was associated with shorter coleoptile length and higher residual starch content, suggesting that less efficient starch utilization may have impaired growth during germination.ConclusionsThe present report documents for the first time a molecular phenotype due to the absence of SBEI, and suggests strongly that it is associated with altered physiological function of the starch in vivo. We believe that these results provide a plausible rationale for the conservation of SBEI in plants in both monocots and dicots, as greater seedling vigor would provide an important survival advantage when resources are limited.

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Starch Granule (Amyloplast) Development in Endosperm of Several Zea mays L. Genotypes Affecting Kernel Polysaccharides

Cited by 35 publications

References 6 publications

Elongated phytoglycogen chain length in transgenic rice endosperm expressing active starch synthase IIa affects the altered solubility and crystallinity of the storage α-glucan

Elongated phytoglycogen chain length in transgenic rice endosperm expressing active starch synthase IIa affects the altered solubility and crystallinity of the storage α-glucan

Arabidopsis mutants Atisa1 and Atisa2 have identical phenotypes and lack the same multimeric isoamylase, which influences the branch point distribution of amylopectin during starch synthesis

Deficiency of maize starch-branching enzyme i results in altered starch fine structure, decreased digestibility and reduced coleoptile growth during germination

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