Evolution of amylopectin structure in developing wheat endosperm starch

Kalinga, Danusha N.; Bertoft, Eric; Tetlow, Ian J.; Liu, Qiang; Yada, Rickey Y.; Seetharaman, Koushik

doi:10.1016/j.carbpol.2014.05.008

Cited by 23 publications

(23 citation statements)

References 38 publications

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“…2), suggesting that the structure of the AMP remained unchanged during the development of the endosperm, which confirmed our recent study on the purified AMP component from these samples (Kalinga et al 2014). The λ max values of the AMP fraction were ≈550 nm in all starches (Fig.…”

Section: Discussionsupporting

confidence: 89%

“…λ max can be used to estimate the chain lengths of the corre-sponding glucan polymers, because the length determines the color of the starch-iodine complex in dispersed systems (Banks et al 1971). This observation, together with the fact that the length of the external chains are on average only around 11-12 residues (Kalinga et al 2014), strongly indicated that glucan chains that are long enough to complex with iodine are mainly found as internal segments of the AMP. Therefore, it is reasonable to assume that λ max can be used to estimate the length of glucan polymer segments that are mobile enough in the granular starches to form starch-iodine inclusion complexes at, in this case, the specific a w of 0.97.…”

Section: Discussionmentioning

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: 89%

Section: Discussionmentioning

confidence: 99%

Molecular Structure and Organization of Starch Granules from Developing Wheat Endosperm

et al. 2014

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“…The smaller granular size and molecular size in leaf starch, compared with the sizes in endosperm starch, might sterically inhibit the growth of amylopectin chains. Granules of different sizes have been observed to have different molecular structure (Dhital et al, 2011;Kalinga et al, 2014;Li et al, 2015a) and different molecular size could also result in different chain length. It could be rationalized that smaller granular and molecular size supply less binding sites for the starch-biosynthetic enzymes and results in shorter chains being synthesized.…”

Section: Discussionmentioning

confidence: 99%

Molecular structural differences between maize leaf and endosperm starches

Zhang

Cheng

et al. 2017

Carbohydrate Polymers

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Highlights Leaf starch has much shorter amylopectin chains than endosperm starch  Leaf starch has much smaller molecules than endosperm starch  Leaf starch granules are smaller than endosperm granules  Differences between leaf and endosperm starch related to their biosynthesis process 3 AbstractThe morphology, whole molecular size distribution and chain-length distribution of maize leaf starch have been characterized and compared to its endosperm starch, to better understand differences between leaf and endosperm starch structure, and the relationship with the functions of starch in these organs. Leaf starch is found to have amylopectin with much shorter chains (virtually none with a degree of polymerization, DP, above 70) than the endosperm amylopectin, which has significant numbers of chains with DP up to ~120, and has much smaller molecular size (and is present at a much lower amount) than endosperm starch. It is postulated that these pronounced differences arise from the distinct starch synthesis pathways in these organs, and are consistent with the starches" distinct botanical functions: short-term storage requiring relatively rapid degradation for leaf starch, and high crystallinity and high energy density requiring slow degradation for endosperm starch.

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“…As can be seen in Figure 5, the relative amylose content towards the end of degradation (4 am) was much higher than towards the end of the synthetic phase (4 pm), showing that the amylopectin molecules are synthesized and degraded relatively more rapidly. This remaining starch comprises the central core of the starch granules, which represents the very early stages in granule development, and remains during the night [41,42].…”

Section: Discussionmentioning

confidence: 99%