Starch biosynthesis: experiments on how starch granules grow in vivo

Mukerjea, Romila; Mukerjea, Rupendra; Robyt, John F.

doi:10.1016/j.carres.2008.09.022

Cited by 15 publications

(14 citation statements)

References 20 publications

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“…This trend was in agreement with previous findings (Wei et al 2010). Because starch granules are grown by apposition (Mukerjea et al 2009), the observation of increasing AM content with increasing maturity further suggests the presence of more AM at the periphery than at the center of the starch granule, which agreed with reported findings in mature starch granules of maize and potato (Jane and Shen 1993;Pan and Jane 2000). In wheat endosperm, transcripts of GBSSI start to appear around 6 DAA, becoming most abundant between 14 and 28 DAA (Shewry et al 2009).…”

Section: Discussionsupporting

confidence: 92%

“…Most of the investigations that have been done to study the interior architecture of starch granules were carried out with mature starches, with or without chemical treatments such as acid hydrolysis (Vermeylen et al 2004;Wang et al 2008), enzyme hydrolysis (Blazek and Gilbert 2010;Warren et al 2011), or surface gelatinization (Pan and Jane 2000). Because starch granules grow by developing one layer a day (Buttrose 1960) by apposition (Mukerjea et al 2009), studying starch granules at different developmental stages is a way to investigate the development of interior architecture of the granule. Because starch granules grow by developing one layer a day (Buttrose 1960) by apposition (Mukerjea et al 2009), studying starch granules at different developmental stages is a way to investigate the development of interior architecture of the granule.…”

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confidence: 99%

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Molecular Structure and Organization of Starch Granules from Developing Wheat Endosperm

et al. 2014

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Cereal Chem. 91(6):578-586Wheat starches isolated from seeds harvested between 7 and 49 days after anthesis (DAA) were fractionated into large (>8 μm) and small (<8 μm) granules and studied for starch structure and architecture. Starch granules at 7 DAA possessed unimodal size distribution, whereas it was bimodal at later maturity stages. The apparent amylose fraction of starch granules at early maturity (7 and 14 DAA) consisted of intermediate-type materials, whereas starch at later maturity stages (28 and 49 DAA) contained branched amylose. Wide-angle X-ray scattering (WAXS) revealed a well-developed polymorphic structure already at 7 DAA. Although the presence of a small proportion of B-type crystallites mixed with A-type crystallites was observed in the X-ray diffractogram of starches at early maturation (7 and 14 DAA), it was masked by the A-type crystallites at later maturity stages. However, the large granules had a higher proportion of B-type crystallites and lower relative crystallinity (RC) than their small-granule counterpart. The iodine absorption properties of the starch granules demonstrated different levels of mobility of the starch polymers at different stages of maturity and the mobility of more glucan polymers in the large granule population compared with the small granules at the same maturity stage. Iodine did not change the characteristic A-type crystalline pattern of starch, but it increased RC. Changes in peak width at half height based on WAXS data further suggested the possible interaction of iodine with amylopectin intercluster chain segments and branch chains in formation of inclusion complexes. MATERIALS AND METHODS Materials.Eastern hard red spring wheat (cv. Hobson) at five different stages of kernel development (7, 14, 28, 35, and 49 DAA) were harvested in Ontario, Canada, in 2009. Heads were tagged when 50% of the spikes within the head were anthesized.

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Section: Discussionsupporting

confidence: 92%

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confidence: 99%

Molecular Structure and Organization of Starch Granules from Developing Wheat Endosperm

et al. 2014

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“…More inner and concentric line structures (crystalline lamellae) were easily observed from 4 to 6 DPG in rye than in wheat and triticale. The thickness of growth rings (Mukerjea et al 2009) tended to decrease and, presumably, the granule hardness tended to increase toward the edges. There were no discernable growth rings at the centre of the starch granules or near the hilum (Fig.…”

Section: Morphological Comparisons Of Starch Granules Between Triticamentioning

confidence: 97%

Morphological characterization of triticale starch granules during endosperm development and seed germination

et al. 2011

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X. 2011. Morphological characterization of triticale starch granules during endosperm development and seed germination. Can. J. Plant Sci. 91: 57Á67. The morphology of starch granules and its changes during endosperm development and seed germination in triticale has been investigated under scanning electron microscopy (SEM). Starch granules were rapidly accumulating in triticale endosperm after 6 d postanthesis (DPA). The double-disk structure of starch granules was detected in endosperms from 6 DPA until 27 DPA in triticale and its parental crops, wheat and rye. The equatorial grooves of triticale starch granules were more susceptible to enzymatic hydrolysis than the broad or flat surfaces. Triticale starch was slowly degraded within 4 or 5 d post germination (DPG) and most starch granules were almost completely hydrolyzed after 9 DPG. Morphological changes of starch granules observed under SEM during the in vitro enzymatic hydrolysis were consistent with patterns identified during the germination process. As a hybrid of wheat and rye, triticale inherits many morphological characteristics of starch synthesis and storage in the seed endosperm. However, triticale also possesses unique features of granule shape, size, distribution, and enzyme susceptibility. These results will make it possible to effectively utilize triticale starch in the starch-based production.

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“…Mukerjea et al 45 fractionated potato, wheat, maize, and rice starch granules into 5‐, 10‐, 20‐, and 40‐µm‐sizes. The size with the highest amount of granules was reacted with ADP‐[ 14 C]Glc, washed, and peeled into seven to nine layers, using 90:10 volume proportions of DMSO–water solutions at 10–15°C.…”

Section: Hypothesis For the Initiation Of Starch Granules And Their Gmentioning

confidence: 99%

“…Robyt and coworkers 45 measured starch‐synthase activity in each of eight layers of the uniformly sized potato starch granules. The continual synthesis of starch in the inner layers of the granules gives a higher density of starch and crystallinity in the inner layers than in the outer layers, as they continue to incorporate glucose from ADPGlc every time it is available to the granules, especially those with the low volumes at the core or hilum of the granule and the adjacent inner layers of the granule.…”

Section: Hypothesis For the Initiation Of Starch Granules And Their Gmentioning

confidence: 99%

Evolution of the development of how starch is biosynthesized

Robyt¹,

Mukerjea²

2012

Starch Stärke

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In 1940, C.S. Hanes found that potato phosphorylase transferred a few two to three glucose units from α‐D‐Glc‐1‐P to the nonreducing‐ends of starch. Starting with only α‐D‐Glc‐1‐P and phosphorylase, there was no reaction and a starch‐primer was required for reaction. In 1960, Leloir and coworkers incubated starch granules with ADP‐[14C]Glc and found that 14C‐starch was synthesized. Reaction with β‐amylase gave 14C‐maltose from the nonreducing‐ends and it was assumed that the glucose was being added to the nonreducing‐ends of a primer. Mukerjea and Robyt pulsed and chased starch‐granules with ADP‐[14C]Glc and ADPGlc, and found on reduction and hydrolysis of the 14C‐starch, 14C‐D‐glucitol was obtained, indicating that glucose was added to the reducing‐ends of growing starch‐chains. They obtained highly purified, starch‐synthase that was shown to be free of starch‐primers and gave de novo synthesis, with the addition of glucose to the reducing‐ends. They also found 61 papers from 1964 to 2012 that used 50–100 mM Tris‐type buffers with starch‐synthase and had to add putative‐primers to obtain activity. Mukerjea et al. showed that 25 mM Tris‐type buffers, completely inhibited starch‐synthase. Addition of 10 mg/mL putative‐primers, glycogen or maltotetraose, gave partial (8–57%) reversal of the inhibition. The putative‐primers were activators and not primers; however, their use perpetuated the primer myth for 50 years. A hypothesis is developed, as to how starch granules are initiated and grow in vivo.

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Starch biosynthesis: experiments on how starch granules grow in vivo

Cited by 15 publications

References 20 publications

Molecular Structure and Organization of Starch Granules from Developing Wheat Endosperm

Molecular Structure and Organization of Starch Granules from Developing Wheat Endosperm

Morphological characterization of triticale starch granules during endosperm development and seed germination

Evolution of the development of how starch is biosynthesized

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