Inactivation of allergens and toxins

Morandini, Piero

doi:10.1016/j.nbt.2010.06.011

Cited by 20 publications

(9 citation statements)

References 130 publications

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“…Thus, over-expression of HNL in cassava roots should not present a potential health risk. In contrast, it has been noted that zeolin has a potential allergenic domain, corresponding to the phaseolin β-conglycinin domain [27], [33]. Thus, it is unlikely that zeolin expressing cassava plants will be acceptable for human consumption.…”

Section: Discussionmentioning

confidence: 99%

“…Cyanogenic glucosides have previously been shown to serve as sources of reduced nitrogen which can be assimilated by the β-cyanoalanine synthase pathway for the production of asparagine, aspartate and free ammonia and in turn free amino acids [33]. Cyanogenic glycoside catabolism for protein synthesis was initially observed in germinating rubber seedlings [34].…”

Section: Discussionmentioning

confidence: 99%

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Overexpression of Hydroxynitrile Lyase in Cassava Roots Elevates Protein and Free Amino Acids while Reducing Residual Cyanogen Levels

et al. 2011

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Cassava is the major source of calories for more than 250 million Sub-Saharan Africans, however, it has the lowest protein-to-energy ratio of any major staple food crop in the world. A cassava-based diet provides less than 30% of the minimum daily requirement for protein. Moreover, both leaves and roots contain potentially toxic levels of cyanogenic glucosides. The major cyanogen in cassava is linamarin which is stored in the vacuole. Upon tissue disruption linamarin is deglycosylated by the apolplastic enzyme, linamarase, producing acetone cyanohydrin. Acetone cyanohydrin can spontaneously decompose at pHs >5.0 or temperatures >35°C, or is enzymatically broken down by hydroxynitrile lyase (HNL) to produce acetone and free cyanide which is then volatilized. Unlike leaves, cassava roots have little HNL activity. The lack of HNL activity in roots is associated with the accumulation of potentially toxic levels of acetone cyanohydrin in poorly processed roots. We hypothesized that the over-expression of HNL in cassava roots under the control of a root-specific, patatin promoter would not only accelerate cyanogenesis during food processing, resulting in a safer food product, but lead to increased root protein levels since HNL is sequestered in the cell wall. Transgenic lines expressing a patatin-driven HNL gene construct exhibited a 2–20 fold increase in relative HNL mRNA levels in roots when compared with wild type resulting in a threefold increase in total root protein in 7 month old plants. After food processing, HNL overexpressing lines had substantially reduced acetone cyanohydrin and cyanide levels in roots relative to wild-type roots. Furthermore, steady state linamarin levels in intact tissues were reduced by 80% in transgenic cassava roots. These results suggest that enhanced linamarin metabolism contributed to the elevated root protein levels.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Overexpression of Hydroxynitrile Lyase in Cassava Roots Elevates Protein and Free Amino Acids while Reducing Residual Cyanogen Levels

et al. 2011

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“…Morandini (2010) melaporkan bahwa perubahan basa berupa insersi atau delesi yang terjadi pada runutan basa suatu gen dapat mengakibatkan perubahan aktivitas protein dari gen tersebut. Hasil-hasil penelitian yang pernah dilakukan oleh para peneliti tembakau menggunakan genotipe-genotipe mutan dari kultivar Burley 21 yang memiliki kandungan nikotin berbeda-beda memperlihatkan bahwa variasi kandungan nikotin di daun berkorelasi dengan tingkat aktivitas enzim putresina N-metiltransferase yang disandikan oleh gen PMT di akar tanaman tembakau (Saunders dan Bush 1979;Hibi 1994;Reed dan Jelesko 2004), sehingga sejalan dengan hasil penelitian ini.…”

Section: Analisis Pengelompokanunclassified

PENGELOMPOKKAN SEPULUH VARIETAS TEMBAKAU (Nicotiana tabacum) BERDASARKAN KERAGAMAN RUNUTAN BASA PARSIAL GEN PMT(PUTRESCINE N-METHYLTRANSFERASE) Clustering of ten tobacco (Nicotiana tabacum) varieties based on the partial PMT (putrescine N-methyltranfera

Basuki¹,

Sudarsono²

2017

j. penelitian tanam. industri

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ABSTRAK(PMT) yang berperan dalam lintasan biosintesis nikotin pada tanaman tembakau (Nicotiana tabacum). Sepuluh varietas tembakau yang memiliki perbedaan tingkat kadar nikotin diuji untuk mempelajari: 1) keragaman runutan basa parsial gen PMT dari masing-masing varietas, dan 2) pengelompokan sepuluh varietas tembakau yang diuji berdasarkan keragaman runutan basa parsial gen PMT. Keragaman runutan basa dianalisis dengan mensejajarkan data runutan basa dari sepuluh varietas tembakau yang diuji dengan runutan basa dari Ntpmt_Sindoro1 (JQ438825) yang telah tersimpan dalam database genbank NCBI. Hasil pensejajaran digunakan untuk menghitung matriks jarak, yang selanjutnya digunakan untuk menganalisis pengelompokan sepuluh varietas tembakau. Hasil analisis memperlihatkan adanya variasi ukuran dan jumlah runutan basa parsial gen PMT asal sepuluh varietas tembakau yang dianalisis. Hasil analisis juga memperlihatkan bahwa runutan basa parsial gen PMT tersebut berasal/diturunkan dari sumber (ancestor) yang sama yang terkait dengan biosintesis nikotin pada tembakau. Runutan basa parsial gen PMT dari sepuluh varietas yang dianalisis memisahkan antara kelompok tembakau introduksi (kadar nikotin rendah-sedang) dengan kelompok tembakau lokal (kadar nikotin sedang-tinggi). Dua kelompok memisah berdasarkan level kadar nikotin, dan perbedaan/perubahan susunan basa pada situs-situ tertentu dari runutan basa parsial gen PMT yang dianalisis. Informasi tentang mutasi yang terjadi pada situs-situs runutan basa dari parsial gen PMT dapat digunakan untuk mempelajari keterkaitan antara perubahan basa pada fragmen gen PMT dengan kandungan nikotin total tembakau yang terjadi selama proses evolusi. ABSTRACTPMT gene is the gene encoded putrescine N-methyltransferase which is related to nicotine biosinthesis in tobacco (Nicotiana tabacum). Ten tobacco varieties with different nicotine level were used in this study. The aims of this study were: 1) to analyze the partial PMT gene sequence diversity among ten tobacco varieties, and 2) to evaluate the closedrelationship among ten tobacco varieties based on their partial PMT gene sequences diversity. Sequence diversity was analyzed by multiple sequence alignment between the partial PMT gene sequence of the ten tobacco varieties and Ntpmt_Sindoro1 sequence (JQ438825) deposited in the NCBI gene-bank database. The phylogenetic relationship among the sequences was inferred by genetic distance between pairs of sequences using the pairwise and multiple sequence alignment analysis. Analysis of the sequences showed that all varieties analyzed had varied in size and number of the PMT gene fragments yielded. The analysis also revealed that the partial PMT gene sequences are coming from the same ancestor which related to nicotine biosynthesis in tobacco. Phylogenetic analysis separated the partial PMT gene sequences into two different branches significantly (bootstrap value = 100), and clustered together based on tobacco types with different nicotine level in which could be due to some bases changed on the ...

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“…Metabolic engineering of plants Plant Biotechnology Journal ª 2013 Society for Experimental Biology, Association of Applied Biologists and Blackwell Publishing Ltd, Plant Biotechnology Journal, 11, 253-267 has achieved remarkable goals in the past 10 years, being able to modulate the content of several endogenous and useful compounds, especially vitamins, aa and lipids, but little of this achieved commercialization. Many other benefits are within reach, for both developed and developing countries, among which the reduction of toxins and allergens in several crops (Gallo and Sayre, 2009;Morandini, 2010). However brighter the future might look, a substantial rethinking of current regulatory framework is required if the promised benefits are to be fulfilled (Giddings et al, 2012;G omez-Galera et al, 2012;Miller, 2010;Potrykus, 2010).…”

Section: The Dos and Don'ts Of Metabolic Engineersmentioning

confidence: 99%

Control limits for accumulation of plant metabolites: brute force is no substitute for understanding

Morandini

2013

Plant Biotechnology Journal

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SummaryWhich factors limit metabolite accumulation in plant cells? Are theories on flux control effective at explaining the results? Many biotechnologists cling to the idea that every pathway has a rate limiting enzyme and target such enzymes first in order to modulate fluxes. This often translates into large effects on metabolite concentration, but disappointing small increases in flux. Rate limiting enzymes do exist, but are rare and quite opposite to what predicted by biochemistry. In many cases however, flux control is shared among many enzymes. Flux control and concentration control can (and must) be distinguished and quantified for effective manipulation. Flux control for several 'building blocks' of metabolism is placed on the demand side, and therefore increasing demand can be very successful. Tampering with supply, particularly desensitizing supply enzymes, is usually not very effective, if not dangerous, because supply regulatory mechanisms function to control metabolite homeostasis. Some important, but usually unnoticed, metabolic constraints shape the responses of metabolic systems to manipulation: mass conservation, cellular resource allocation and, most prominently, energy supply, particularly in heterotrophic tissues. The theoretical basis for this view shall be explored with recent examples gathered from the manipulation of several metabolites (vitamins, carotenoids, amino acids, sugars, fatty acids, polyhydroxyalkanoates, fructans and sugar alcohols). Some guiding principles are suggested for an even more successful engineering of plant metabolism.Rate limiting steps: do they exist? Yes, but they are not quite as expectedAs most research in plant biotechnology aims at manipulating the amount of selected metabolic products, the question arises: what limits their accumulation? The dominant textbook wisdom wasand partially still is -that in every metabolic pathway there is a reaction limiting the flux (defined as the 'rate limiting step' (RLS) of the pathway), and therefore ultimately the accumulation of downstream metabolites. As a sample quote of this belief, take the following from Ishihara et al. Let us first clarify the relationship between flux and metabolite accumulation. If flux remains unchanged, a metabolite concentration can increase only if other metabolite(s) in the pathway decrease; a constant flux imposes a constraint on the achievable fold accumulation of any metabolite. On the contrary, when flux increases, the end product (as well as other intermediates) can accumulate several folds. It must be noted that even small changes in flux (say a few percent of usual flux) may lead to a mM increase of a metabolite if the accumulation is protracted for many days.The idea of the RLS can be likened, in its simplest and extreme form, to a tollgate on a highway (Figure 1): the number of cars processed in unit time is independent from the number of cars waiting in the queue or of those beyond the gate. In metabolic terms, this comparison is untenable, not only because the rate of an enzymatic r...

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Inactivation of allergens and toxins

Cited by 20 publications

References 130 publications

Overexpression of Hydroxynitrile Lyase in Cassava Roots Elevates Protein and Free Amino Acids while Reducing Residual Cyanogen Levels

Overexpression of Hydroxynitrile Lyase in Cassava Roots Elevates Protein and Free Amino Acids while Reducing Residual Cyanogen Levels

PENGELOMPOKKAN SEPULUH VARIETAS TEMBAKAU (Nicotiana tabacum) BERDASARKAN KERAGAMAN RUNUTAN BASA PARSIAL GEN PMT(PUTRESCINE N-METHYLTRANSFERASE) Clustering of ten tobacco (Nicotiana tabacum) varieties based on the partial PMT (putrescine N-methyltranfera

Control limits for accumulation of plant metabolites: brute force is no substitute for understanding

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