Import of sucrose and its transformation to starch in the developing sorghum caryopsis

Singh, Rangil; Asthir, Bavita

doi:10.1111/j.1399-3054.1988.tb04941.x

Cited by 22 publications

(10 citation statements)

References 44 publications

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“…The activity of sucrose synthase (UDPglucose-fructose-2-a-D glucosyltransferase) was assayed by the method of Morell and Copeland (1985). The soluble acid invertase (pH 4.8) and soluble neutral invertase (pH 7.5) (b-D-fructofuranoside fructohydrolase) activities were assayed essentially by the method described previously by Singh and Asthir (1988).…”

Section: Soluble Acid Invertase Soluble Neutral Invertase and Sucrosmentioning

confidence: 99%

Apical stem culturing to enhance cell sap assimilates towards grain sucrose and glutamine metabolism in wheat

Kaur

Asthir

Bains

2015

Cereal Research Communications

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Apical stem culturing offers an alternative approach of manipulating cell sap for wheat grain carbon and nitrogen metabolism in a near in vivo conditions. Employing this technique, role of sucrose and glutamine in transport stream on sucrose metabolism, ammonia assimilation and aminotransferase activities were assessed towards starch and protein accumulation in two wheat genotypes PBW 343 (low yield) and PBW 621 (high yield). At mid-milky stage, detached tillers were cultured in complete liquid medium containing varied concentration of glutamine and sucrose for seven days during year 2012-13 and 2013-14. Increasing glutamine concentration from 17 to 25 mM in the culture medium having 117 mM sucrose enhanced activities of nitrate reductase, glutamate synthase, glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT) at 4 days after culturing (DAC) in correspondence with an increase in soluble protein content. However, at 7 DAC content of soluble protein decreased whereas starch accumulation increased showing, thereby a compensatory effect on carbon and nitrogen metabolism. Apparently, activities of sucrose synthase, soluble acid and neutral invertase significantly decreased. Increasing sucrose concentration from 117 to 125 mM led to an increase in transformation of sugars to starch in grain but protein content decreased. PBW 621 showed high protein content due to higher activities of GOT, GPT at 4 DAC which subsequently increased carbon skeleton of proteins towards starch synthesis at 7 DAC. Grain filling processes in terms of soluble sugars/starch were strongly correlated to invertase activities whereas proteins to aminotransferases.Keywords: acid invertase, carbon/nitrogen metabolism, glutamate oxaloacetate transaminase, glutamate pyruvate transaminase, sucrose synthase Abbreviations: NR -nitrate reductase, GOGAT -glutamate synthase, GOT -glutamate oxaloacetate transaminase, GPT -glutamate pyruvate transaminase, SS -sucrose synthase, AI -acid invertase, NI -neutral invertase, DAC -days after culturing

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Section: Soluble Acid Invertase Soluble Neutral Invertase and Sucrosmentioning

confidence: 99%

Apical stem culturing to enhance cell sap assimilates towards grain sucrose and glutamine metabolism in wheat

Kaur

Asthir

Bains

2015

Cereal Research Communications

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“…The soluble acid invertase (pH 4.8) and soluble neutral invertase (pH 7.5) (β-D-fructofuranoside fructohydrolase) activities were assayed essentially by the method described previously by Singh and Asthir (1988).…”

Section: Sucrose Synthase Soluble Acid Invertase and Soluble Neutralmentioning

confidence: 99%

Hydroponic culturing upregulates sucrose and glutamine metabolism by enhancing their utilization via intermediates of aerobic pathway in wheat

Kaur

Asthir

2016

Cereal Research Communications

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Two wheat genotypes were grown in hydroponic culture, containing 4 mM KNO 3 , NH 4 Cl and NH 4 NO 3 . Activities of N metabolizing enzymes, aminotransferases, carbohydrate and TCA cycle enzymes were analyzed along with protein, amino acid, N, sugar content and growth parameters in shoot and root. After 12 days, the size of shoot and root system decreased significantly when plants were supplied with NH 4 Cl as exclusive N source. Under NH 4 NO 3 growth parameters, N and carbon metabolism were elevated as compared to NH 4 Cl but less than KNO 3 source indicating inhibition of NH 4 + toxicity by NO 3 -uptake. Our results suggested that GDH, aminotransferases and PEPC play an important role in ammonium detoxification by its incorporation into amino acids. Thus, the morphologic differences among plants growing in NH 4 + or NO 3 -nutrition confirm the hypothesis that N source determines the growth habit of plant in wheat by modulating the endogenous levels of protein and sugar content.

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“…Total free sugars were extracted from fresh grains with hot ethanol (Singh & Asthir 1988) and measured by the method of Dubois et al (1956). Starch was extracted from the sugar-free residue as reported by Singh & Juliano (1977) and was measured by the method of Pucher et al (1948).…”

Section: Carbohydrate Analysismentioning

confidence: 99%

“…14 C activity was determined in ethanol-extracted free sugars and in starch (Singh & Asthir 1988). The extracted l4 C-sugars were resolved in duplicate on Whatman No.…”

Section: Incorporation Ofmentioning

confidence: 99%

“…This technique mimics in vivo conditions of cellular metabolism and in our laboratory it has already generated important information on regulation of sucrose metabolism in cereals (Singh et al 1978;Singh & Asthir 1988;Singh et al 1991;Goyal et al 1990;Randhawa & Singh 1994) and legumes . Based on our present results, we propose that whereas triose phosphates may act as precursors of starch synthesis in sorghum (Sorghum bicolor) grain, hexose phosphates, or ADPG may be involved as direct precursors of starch synthesis in the wheat grain.…”

Section: Introductionmentioning

confidence: 99%

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Alternate routes for starch synthesis in developing grains of wheat and sorghum: Indirect evidence through its regulation by inorganic phosphates and organic acids

Randhawa

Singh

1998

New Zealand Journal of Crop and Horticultural Science

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fructose 1,6-bisphosphate aldolase, and triose phosphate isomerase in sorghum grain as compared to those in wheat grain.Keywords inorganic phosphates; liquid culturing; organic acids; starch synthesis; sorghum; wheat Abstract The path of carbon from sucrose to starch in developing grains appears to be different in wheat (Triticum aestivum) and sorghum (Sorghum bicolor). In this paper we present indirect evidence in support of this hypothesis. Detached ears, carrying actively metabolising grains, were cultured in complete liquid media manipulated with respect to inorganic phosphates and organic acids. 14 C-incorporation studies indicated a higher level of metabolism of sucrose before starch formation in sorghum grain as compared to that in wheat grain. Starch and protein contents drastically decreased in sorghum grain in response to exogenously-supplied inorganic phosphate and inorganic pyrophosphate. In contrast, these inorganic phosphates had no such effect on starch and protein accumulation in wheat grain, a-ketoglutarate and citrate in sucrose-free culture medium increased the starch content of wheat grain. Conversely, these organic acids markedly decreased the starch content of sorghum grain. This difference in the response of wheat and sorghum grains to inorganic phosphates and organic acids leads us to suggest that whereas triose phosphates act as precursors of starch in sorghum grain, hexose phosphates and/or adenosine 5'-diphosphoglucose may act as direct precursors of starch in wheat grain. This hypothesis is supported by the observation of higher specific activities of some selected glycolytic enzymes, such as phosphoglucoisomerase, ATP-dependent phosphofructokinase,

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Import of sucrose and its transformation to starch in the developing sorghum caryopsis

Cited by 22 publications

References 44 publications

Apical stem culturing to enhance cell sap assimilates towards grain sucrose and glutamine metabolism in wheat

Apical stem culturing to enhance cell sap assimilates towards grain sucrose and glutamine metabolism in wheat

Hydroponic culturing upregulates sucrose and glutamine metabolism by enhancing their utilization via intermediates of aerobic pathway in wheat

Alternate routes for starch synthesis in developing grains of wheat and sorghum: Indirect evidence through its regulation by inorganic phosphates and organic acids

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