Interactions Among Number of Spikelets, Number of Grains and Grain Weight in the Spikes of Wheat (Triticum aestivum L.)*

Pinthus, M. J.; Millet, E.

doi:10.1093/oxfordjournals.aob.a085523

Cited by 36 publications

(18 citation statements)

References 6 publications

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“…A number of studies have identified conditions that affect flower survival and thus seed number in wheat (15,16,(29)(30)(31)(32)(33). However, no published evidence exists on the effects of increased seed enzyme activity and sink strength on the survival of developing seeds in wheat or any other plants.…”

Section: Discussionmentioning

confidence: 99%

Enhanced ADP-glucose pyrophosphorylase activity in wheat endosperm increases seed yield

Smidansky

Clancy

Meyer³

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

271

178

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Yield in cereals is a function of seed number and weight; both parameters are largely controlled by seed sink strength. The allosteric enzyme ADP-glucose pyrophosphorylase (AGP) plays a key role in regulating starch biosynthesis in cereal seeds and is likely the most important determinant of seed sink strength. Plant AGPs are heterotetrameric, consisting of two large and two small subunits. We transformed wheat (Triticum aestivum L.) with a modified form of the maize (Zea mays L.) Shrunken2 gene (Sh2r6hs), which encodes an altered AGP large subunit. The altered large subunit gives rise to a maize AGP heterotetramer with decreased sensitivity to its negative allosteric effector, orthophosphate, and more stable interactions between large and small subunits. The Sh2r6hs transgene was still functional after five generations in wheat. Developing seeds from Sh2r6hs transgenic wheat exhibited increased AGP activity in the presence of a range of orthophosphate concentrations in vitro. Transgenic Sh2r6hs wheat lines produced on average 38% more seed weight per plant. Total plant biomass was increased by 31% in Sh2r6hs plants. Results indicate increased availability and utilization of resources in response to enhanced seed sink strength, increasing seed yield, and total plant biomass. W heat (Triticum aestivum L.) is one of the world's most important crop plants. An estimated 610 million metric tons of wheat seed were harvested worldwide in the 1997͞98 growing season (1). Wheat seed yield is determined by seed number and weight. Starch is the major component of wheat yield, comprising 70% of wheat seed dry weight. ADP-glucose pyrophosphorylase (AGP; EC 2.7.7.27), an allosterically regulated heterotetramer consisting of two large and two small subunits, catalyzes the rate-limiting reaction in starch biosynthesis in plants (reviewed in refs. 2 and 3). AGP uses the substrates glucose 1-phosphate and ATP to produce ADPglucose and pyrophosphate (4). ADP-glucose is then used as the glucose donor for starch synthases. The positive allosteric effector of AGP is 3-phosphoglycerate, whereas the negative allosteric effector is orthophosphate (Pi) (2, 3). Maize endosperm AGP (5) large subunits are encoded by Shrunken2 (Sh2) (6), whereas small subunits are encoded by Brittle2 (Bt2) (7).Inhibition of AGP activity by Pi appears to limit starch biosynthesis and yield in crop plants. Evidence for this has come from studies of a modified AGP large subunit in maize (8) and from use of an altered bacterial AGP in potato (9). In both cases, AGP modification caused reduced sensitivity to Pi inhibition, resulting in enhanced yield, manifested as increased seed weight in maize (8) and increased starch content in potato (9). Instability of AGP may be an additional limitation on cereal yield. AGP is perhaps the most heat-labile starch biosynthetic enzyme in maize (10-12). A single amino acid substitution in the maize large subunit that conditions more stable large subunit-small subunit interactions (13) may lead to enhanced AGP activity and increa...

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Section: Discussionmentioning

confidence: 99%

Enhanced ADP-glucose pyrophosphorylase activity in wheat endosperm increases seed yield

Smidansky

Clancy

Meyer³

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

271

178

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“…In the field in 1976 it might have been due tathe exceptionally hot, dry, weather which was very unfavourable for grain growth. It might be a property of the varieties used: differences between varieties in response to spikelet removal have been reported (Pinthus & Millet, 1978;Fischer & HilleRisLambers 1978).…”

Section: Introductionmentioning

confidence: 99%

Effects of decreasing the number of grains in ears of cvs Hobbit and Maris Huntsman winter wheat

Radley

Thorne

1981

Annals of Applied Biology

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At 6 days after anthesis, grain numbers in ears of Maris Huntsman and Hobbit winter wheat growing in the field were decreased either by removing the two lower grains in each spikelet (degraining) or by removing the top half of the ear (halving). At maturity, degraining increased the dry weight of the third grains in each spikelet of Maris Huntsman by 11% and of Hobbit by 40%, compared with third grains in intact ears. Halving increased the mean dry weight of all the grains in the lower six spikelets of the ear slightly less; it increased the number of grains in Hobbit but not in Maris Huntsman. The responses to halving in Hobbit were greater with additional nitrogen fertiliser.At 28 days after anthesis in both varieties, degraining increased grain dry weight and the amount of water, reducing sugar, amino acids and total nitrogen in third grains. Effects of halving on these properties of the two lower grains of each spikelet were much less or nil. The increases in nitrogen content of grains at 28 days and at maturity caused by degraining or halving were relatively greater than the increases in dry weight and were similar in the two varieties.

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“…In one case where such an attempt was made, the direct effect of N status of the plant appeared to be small (Pinthus & Millet, 1978). Some quantitive consequences of nitrogen metabolism Yield-uptake and uptake-application relations…”

Section: Effect Of Nitrogen On Organ Formationmentioning

confidence: 99%

Modelling the effects of nitrogen on canopy development and crop growth

Keulen¹,

Goudriaan

Seligman³

1989

Plant Canopies

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Interactions Among Number of Spikelets, Number of Grains and Grain Weight in the Spikes of Wheat (Triticum aestivum L.)*

Cited by 36 publications

References 6 publications

Enhanced ADP-glucose pyrophosphorylase activity in wheat endosperm increases seed yield

Enhanced ADP-glucose pyrophosphorylase activity in wheat endosperm increases seed yield

Effects of decreasing the number of grains in ears of cvs Hobbit and Maris Huntsman winter wheat

Modelling the effects of nitrogen on canopy development and crop growth

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