Genomic and Transgenics for Gums And Starch

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Genomic and Transgenics for Gums And Starch


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Genomic and Transgenics for Gums And Starch:

Genomic and Transgenics for Gums And Starch GEETIKA 2012A41D


Formation of starch. Source: Emmet S. Goff and D. D. Mayne,  First Principles of Agriculture  (New York: American Book Company, 1904) 27 Starch  or  amylum  is a carbohydrate consisting of a large number of glucose units joined by glycosidic bonds. This polysaccharide is produced by all green plants as an energy store. It is the most common carbohydrate in the human diet and is contained in large amounts in such staple foods aspotatoes, wheat, maize (corn), rice, and cassava.


STARCH Pure starch is a white, tasteless and odourless powder that is insoluble in cold water or alcohol. It consists of two types of molecules: the linear and helical amylose and the branched amylopectin. Depending on the plant, starch generally contains 20 to 25% amylose and 75 to 80% amylopectin by weight. Glycogen, the glucose store of animals, is a more branched version of amylopectin. Starch is processed to produce many of the sugars in processed foods. Dissolving starch in warm water gives wheatpaste, which can be used as a thickening, stiffening or gluing agent. The biggest industrial non-food use of starch is as adhesive in the papermaking process. Starch can be applied to parts of some garments before ironing, to stiffen them; this is less usual now than in the past.

What are natural gums?:

What are natural gums? Natural gums  are polysaccharides of natural origin, capable of causing a large viscosity increase in solution, even at small concentrations. In the food industry they are used as thickening agents, gelling agents, emulsifying agents, and stabilizers. In other industries, they are also used as adhesives, binding agents, crystan inhibitors, clarifying agents, encapsulating agents, flocculating agents, swelling agents, foam stabilizers, etc. Most often these gums are found in the woody elements of plants or in seed coatings.


Genomics is the study of genome ( functions and interactions of all the genes in the genome .) Genome is the whole of the genetic information being carried by an organism.

What is Transgenics? :

What is Transgenics? Technology used to alter the genetic material of living cells in order to make them capable of producing new substances (e.g. An insect toxin) or functioning differentially (e.g. Tolerance to saline soil). Transgenic or Genetically modified plants: Plants, which carry additional, stably integrated and expressed foreign genes.

Starch yield:

Starch yield AGPase

Starch quality:

Starch quality

Starch quality:

Starch quality

Gums :

Gums They are polysaccharides , capable of causing a large increase in viscosity of the solutions, even at small concentrations . These are formed from the disintegration of internal plant tissues, mostly from the decomposition of cellulose called gummosis.  Polymeric materials that can be dissolved or dispersed in water to give a thickening and gelling effect. They are soluble in water but are insoluble in alcohol and ether .


Natural gums can be classified according to their origin or uncharged or ionic polymers. Commercial plant gums are: Gum tragacanth ( Astrangalus gummifer ) Karaya gum ( Sterculia urens ) Gum arabic ( Acacia senegal) Guar gum ( Cyamopsis tetragonoloba )


Sources : Tree exudates Plant seed (seed coatings) Stem Woody elements of plants Seaweed Application: Food industry thickening agents , Gelling agents, Emulsifying agents , Stabilizers . Adhesives, binding agents, crystallization inhibitors, clarifying agents, encapsulating agents, flocculating agents, swelling agents, foam stabilizers, etc.  


Common gums Carrageenan Alginates Locust bean gum Pectin Cellulose gum Gelatin Agar-agar

GENOMICS AND TRANSGENICS FOR GUMS Xanthan Gum: produced via genetic engineering :

GENOMICS AND TRANSGENICS FOR GUMS Xanthan Gum: produced via genetic engineering Xanthomonas campestris is a bacterial plant pathogen, infecting vascular tissues and consuming the glucose therein, producing a gummy byproduct called xanthan Mutated strain of Xanthomonas campestri ™ could degrade lactose in lieu of the usual glucose . A strain of X. campestris that can turn a waste product into a profitable polymer is useful for food scientists, because lactose is available in abundance as a by product of cheese making.


CONTINUED... In 1980s, a β-galactosidase gene from Escherichia coli was inserted into X. campestris to create a genetically modified xanthan-gum producer; its ability to ferment xanthan gum from a whey substrate was comparable with the ability of the unmodified bacterium to ferment xanthan gum from the traditional glucose-based substrate.

Production of recombinant plant gum with tobacco cell culture :

Production of recombinant plant gum with tobacco cell culture Many plant gums, such as gum arabic, contain hydroxyproline-rich glycoproteins (HRGPs). In transgenic BY2 Nicotiana tabacum (tobacco) cells, a synthetic gene encoding a novel HRGP-based gum, designated gum arabic-8 or (GA) 8 is expressed . (GA) 8 encoded eight repeats of the consensus polypeptide sequence of gum arabic glycoprotein (GAGP): Gly-Pro-His-Ser-Pro-Pro-Pro-Pro-Leu-Ser-Pro-Ser-Pro-Thr-Pro-Thr-Pro-Pro-Leu , in which most of the Pro residues were post translationally modified to hydroxyproline (Hyp).


Starch Starch is a carbohydrate consisting of a large number of glucose units joined by glycosidic bonds. It is the most common carbohydrate in the human diet. Sources of starch : potatoes wheat maize rice It consists of two types of molecules: Linear amylose Branched amylopectin . Starch contains: 20 to 25% amylose. 75 to 80% amylopectin.


Schematic representation of the pathway of starch biosynthesis, its subcellular compartmentation, and distribution of flux control in photosynthetic leaves (A) and heterotrophic tissues (B). Geigenberger P. Plantphysiol 2011;155:1566-1577 ©2011 by American Society of Plant Biologists


Regulation of plastidial AGPase by multiple mechanisms allows starch synthesis to respond across a range of time scales to a variety of physiological and environmental stimuli. Geigenberger P. Plantphysiol 2011;155:1566-1577 ©2011 by American Society of Plant Biologists


Posttranslational redox regulation of starch biosynthesis in response to light and sugar signals. Geigenberger P. Plantphysiol 2011;155:1566-1577 ©2011 by American Society of Plant Biologists


Industrial applications Papermaking Clothing starch Packing peanuts Drop ceiling tiles Textile printing thickener. Bioplastics synthetic polymers (biodegradable). As a substitute for talcum powder. Glucose from starch can be further fermented to biofuel corn ethanol .

Genomics and Transgenics for starch:

Modified starch is a chemically modified to allow the starch to function properly under conditions frequently encountered during processing or storage, such as high heat, high shear, low pH, freeze/thaw and cooling. The modified food starches are E coded according to the International Numbering System for Food Additives (INS). Genomics and Transgenics for starch


MODIFIED STARCHES 1400 Dextrin 1401 Acid-treated starch 1402 Alkaline-treated starch 1403 Bleached starch 1404 Oxidized starch 1405 Starches, enzyme-treated 1410 Monostarch phosphate 1412 Distarch phosphate 1413 Phosphated distarch phosphate 1414 Acetylated distarch phosphate 1420 Starch acetate 1422 Acetylated distarch adipate 1440 Hydroxypropyl starch 1442 Hydroxypropyl distarch phosphate 1443 Hydroxypropyl distarch glycerol 1450 Starch sodium octenyl succinate 1451 Acetylated oxidized starch


STARCH MODIFICATION BY GENETIC ENGINEERING Genes encoding the main enzyme of starch biosynthesis have been cloned and used to produce transgenic lines.


EXAMPLES: GRANULE BOUND STARCH SYNTHASE I GBSS I is the main enzyme of amylose biosynthesis. GBSS I activity cause more amylose content. Supression of GBSS I activity (by antisense RNA technology) in potato yield an amylose free or "waxy" starch in potato. This was the first genetic modification of starch reported in 1991.


SOLUBLE STARCH SYNTHASE SSS is the main enzyme of amylopectin biosynthesis. It has two isoforms called SSS 1 and SSS 2. A freeze-thaw stable potato starch has been created by simultaneous down regulation of all the starch synthase , GBSSI , SSS1 and SSS2 genes using antisense RNA tecnology. This manipulation yielded an amylose-free short chain amylopectin. Antisense RNA technology


STARCH BRANCHING ENZYME Increased SBE activity is expected to increase branching, while its supression should reduce the amount of amylopectins. In potato, SBE activities were supressed to <1% of the wild type resulted in very high amylose starch (high amylose , low amylopectin,and high phosphorous level) which has novel food and industrial application. -

Genetic modification of cassava for enhanced starch production:

Genetic modification of cassava for enhanced starch production Transgenic plants with enhanced tuberous root ADP-glucose pyrophosphorylase (AGPase) activity achieved by expressing a modified form of the bacterial glgC gene under the control of a Class I patatin promoter. AGPase catalyses the rate-limiting step in starch biosynthesis, and therefore the expression of a more active bacterial form of the enzyme was expected to lead to increased starch production. Transgenic plants (three) expressing the glgC gene had up to 70% higher AGPase activity. Plants having the highest. AGPase activities had up to a 2.6-fold increase in total tuberous root biomass

Examples of transgenic for starch:

Examples of transgenic for starch


Conclusion Conventional production of starch and gums is not sufficient in the face of the pressure being put by the rising demand from industrial including the edibles. Transgenic technology is capable of increase not only in yield but also in quality. Transgenic has been successfully utilized in the production of both starch and gum. Issues associated with risk assessment, however need to be dealt at priority particularly when the produce is meant for human consumption.



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