Starch synthesis in cereal grains

Tomlinson, Kim; Denyer, Kay

doi:10.1016/s0065-2296(05)40001-4

Cited by 78 publications

(70 citation statements)

References 186 publications

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“…Amylose accumulation in endosperm lags behind that of amylopectin and continues after amylopectin synthesis ceases ( Fig. 1B; Tomlinson and Denyer, 2003). This could be explained, at least in part, by the expression patterns of endosperm-specific GBSS1a and SS genes (Fig.…”

Section: In the Developing Endosperm Starch Breakdown Occurs In The mentioning

confidence: 95%

“…The rate of starch accumulation is believed to be very similar to that of starch synthesis (Tomlinson and Denyer, 2003), ensuring that there is no significant turnover of starch in the starchy endosperm during the filling period. Thus, the expression of starch-degrading enzymes during endosperm development (Fig.…”

Section: In the Developing Endosperm Starch Breakdown Occurs In The mentioning

confidence: 99%

“…Much attention has been paid over the last decades to better understanding the process of starch synthesis in cereal grains (for review, see Smith, 1999;Emes et al, 2003;James et al, 2003;Tomlinson and Denyer, 2003;Morell and Myers, 2005). At least four classes of enzyme activities have been identified as being necessary for starch granule synthesis.…”

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confidence: 99%

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Spatiotemporal Profiling of Starch Biosynthesis and Degradation in the Developing Barley Grain

Borisjuk²,

et al. 2009

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Barley (Hordeum vulgare) grains synthesize starch as the main storage compound. However, some starch is degraded already during caryopsis development. We studied temporal and spatial expression patterns of genes coding for enzymes of starch synthesis and degradation. These profiles coupled with measurements of selected enzyme activities and metabolites have allowed us to propose a role for starch degradation in maternal and filial tissues of developing grains. Early maternal pericarp functions as a major short-term starch storage tissue, possibly ensuring sink strength of the young caryopsis. Gene expression patterns and enzyme activities suggest two different pathways for starch degradation in maternal tissues. One pathway possibly occurs via a-amylases 1 and 4 and b-amylase 1 in pericarp, nucellus, and nucellar projection, tissues that undergo programmed cell death. Another pathway is deducted for living pericarp and chlorenchyma cells, where transient starch breakdown correlates with expression of chloroplast-localized b-amylases 5, 6, and 7, glucan, water dikinase 1, phosphoglucan, water dikinase, isoamylase 3, and disproportionating enzyme. The suite of genes involved in starch synthesis in filial starchy endosperm is much more complex than in pericarp and involves several endosperm-specific genes. Transient starch turnover occurs in transfer cells, ensuring the maintenance of sink strength in filial tissues and the reallocation of sugars into more proximal regions of the starchy endosperm. Starch is temporally accumulated also in aleurone cells, where it is degraded during the seed filling period, to be replaced by storage proteins and lipids.

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Section: In the Developing Endosperm Starch Breakdown Occurs In The mentioning

confidence: 95%

Section: In the Developing Endosperm Starch Breakdown Occurs In The mentioning

confidence: 99%

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Spatiotemporal Profiling of Starch Biosynthesis and Degradation in the Developing Barley Grain

Borisjuk²,

et al. 2009

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“…moiety of ADPglucose is the substrate for synthesis of starch polymers (a-1,4, a-1,6-linked glucans) via starch synthases, starch-branching enzymes and the starch-debranching enzyme isoamylase. The precise mechanism by which the starch polymers organize to form the semi-crystalline starch granule is not understood, but it requires the presence of three to five distinct isoforms of starch synthase and two of starch-branching enzyme (Ball and Morell, 2003;Tetlow, 2006;Tetlow et al, 2004;Tomlinson and Denyer, 2003). In the absence of any one of the isoforms of these enzymes, or of isoamylase, starch polymer structure and granule formation are usually abnormal.…”

Section: Manipulation Of the Pathway Of Starch Synthesismentioning

confidence: 99%

Prospects for increasing starch and sucrose yields for bioethanol production

Smith

2008

The Plant Journal

156

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SummaryIn the short term, the production of bioethanol as a liquid transport fuel is almost entirely dependent on starch and sugars from existing food crops. The sustainability of this industry would be enhanced by increases in the yield of starch/sugar per hectare without further inputs into the crops concerned. Efforts to achieve increased yields of starch over the last three decades, in particular via manipulation of the enzyme ADPglucose pyrophosphorylase, have met with limited success. Other approaches have included manipulation of carbon partitioning within storage organs in favour of starch synthesis, and attempts to manipulate source-sink relationships. Some of the most promising results so far have come from manipulations that increase the availability of ATP for starch synthesis. Future options for achieving increased starch contents could include manipulation of starch degradation in organs in which starch turnover is occurring, and introduction of starch synthesis into the cytosol. Sucrose accumulation is much less well understood than starch synthesis, but recent results from research on sugar cane suggest that total sugar content can be greatly increased by conversion of sucrose into a non-metabolizable isomer. A better understanding of carbohydrate storage and turnover in relation to carbon assimilation and plant growth is required, both for improvement of starch and sugar crops and for attempts to increase biomass production in second-generation biofuel crops.

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“…ADP-glucose pyrophosphorylase (AGPase), starch synthases (SS), starch branching enzymes (SBE) and starch debranching enzymes (DBE). These enzymes exist in different isoforms and the biochemical characteristics of the enzymes and the expression profiles of the corresponding genes specify the structural organization of starch molecules in plant organs such as the endosperm (see Tomlinson and Denyer, 2003, for a review on starch synthesis and structure in cereals; see also Ball et al, 1998;Buléon et al, 1998;Myers et al, 2000;Nakamura, 2002;Smith, 2001, for other reviews on starch synthesis).…”

Section: Introductionmentioning

confidence: 99%

Diurnal oscillation of SBE expression in sorghum endosperm

Mutisya

Sun

Rosenquist

et al. 2009

Journal of Plant Physiology

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Spatial and temporal expression patterns of the sorghum SBEI, SBEIIA and SBEIIB genes, encoding, respectively, starch branching enzyme (SBE) I, IIA and IIB, in the developing endosperm of sorghum (Sorghum bicolor) were studied. Full-length genomic and cDNA clones for sorghum was cloned and the SBEIIA cDNA was used together with gene-specific probes for sorghum SBEIIB and SBEI. In contrast to sorghum SBEIIB, which was expressed primarily in endosperm and embryo, SBEIIA was expressed also in vegetative tissues. All three genes shared a similar temporal expression profile during endosperm development, with a maximum activity at 15-24 days after pollination. This is different from barley and maize where SBEI gene activity showed a significantly later onset compared to that of SBEIIA and SBEIIB. Expression of the three SBE genes in the sorghum endosperm exhibited a diurnal rhythm during a 24-h cycle.

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Starch synthesis in cereal grains

Cited by 78 publications

References 186 publications

Spatiotemporal Profiling of Starch Biosynthesis and Degradation in the Developing Barley Grain

Spatiotemporal Profiling of Starch Biosynthesis and Degradation in the Developing Barley Grain

Prospects for increasing starch and sucrose yields for bioethanol production

Diurnal oscillation of SBE expression in sorghum endosperm

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