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Highlights: [•] SDNs deliver targeted mutations, gene modification, and DNA insertion. [•] SDNs may overcome constraints within conventional and transgenic plant breeding. [•] Some technical and regulatory issues may challenge the commercial use of SDNs. [Copyright &y& Elsevier]

Abstract: This paper describes the current EU regulatory framework for risk analysis of genetically modified (GM) crop cultivation and market introduction of derived food/feed. Furthermore the risk assessment strategies for GM crops and derived food/feed as designed by the European Food Safety Authority (EFSA) are described on which international agreement exists. Existing flaws in the EU regulatory framework for GMOs have been identified and proposals are put forward to improve current risk analysis procedures for GMOs by taking the SAFE FOODS Risk Analysis Framework into account. The SAFE FOODS framework describes an iterative decision-making process with four distinct stages i.e. framing, risk–benefit assessment, evaluation, and risk management which includes decision-making, and implementation, and a final review stage. Three major changes compared to current risk analyses practices are proposed, i.e. (i) the addition of a formal framing stage, during which problem formulation and the objectives of the risk analysis are established, (ii) enlargement of the scope of the risk assessment, by including the assessment of potential benefits, and an impact analysis of social and economic aspects, and (iii) addition of a formal evaluation stage, in order to weigh risks, costs and benefits and their distribution. Furthermore a broader participation of certain entities, organisations and individual citizens in specific segments of the risk analysis process, in particular in the framing and evaluation stage, is proposed. The proposed changes in current risk analyses practises may contribute to restore consumer confidence in risk analysis process of GMOs in the EU. [Copyright &y& Elsevier]

Abstract: Three main changes to current risk analysis processes are proposed to improve their transparency, openness, and accountability. First, the addition of a formal framing stage would allow interested parties, experts and officials to work together as needed to gain an initial shared understanding of the issue, the objectives of regulatory action, and alternative risk management measures. Second, the scope of the risk assessment is expanded to include the assessment of health and environmental benefits as well as risks, and the explicit consideration of economic- and social-impacts of risk management action and their distribution. Moreover approaches were developed for deriving improved information from genomic, proteomic and metabolomic profiling methods and for probabilistic modelling of health impacts for risk assessment purposes. Third, in an added evaluation stage, interested parties, experts, and officials may compare and weigh the risks, costs, and benefits and their distribution. As part of a set of recommendations on risk communication, we propose that reports on each stage should be made public. [Copyright &y& Elsevier]

The novel intragenic approach to genetic engineering improves existing varieties by eliminating undesirable features and activating dormant traits. It transforms plants with native expression cassettes to fine-tune the activity and/or tissue specificity of target genes. Any intragenic modification of traits could, at least in theory, also be accomplished by traditional breeding and transgenic modification. However, the new approach is unique in avoiding the transfer of unknown or foreign DNA. By consequently eliminating various potential risk factors, this method represents a relatively safe approach to crop improvement. Therefore, we argue that intragenic crops should be cleared through the regulatory process in a timely and cost-effective manner. [Copyright &y& Elsevier]

Abstract: Steroidal glycoalkaloids (SGAs) are potentially harmful specialty metabolites found in Solanaceous plants. Two tri-glycosylated alkaloids, α-chaconine and α-solanine accumulate in potato tubers. Expressed sequence tags (ESTs) were identified in the available database by searching for protein homology to the Sgt1 (SOLtu:Sgt1) steriodalalkaloid galactosyltransferase. The EST sequence data was used to isolate Sgt3 cDNA sequences by polymerase chain reaction (PCR) from a wounded potato tuber cDNA library. The resulting 1515bp open reading frame of Sgt3, encodes a predicted SGT3 amino acid sequence that is 18 residues longer than, 45% identical to, and 58% homologous to the SGT1 protein. The amino-terminal region of the Sgt3 cDNA was used to create an antisense transgene under control of the granule bound starch synthase, GBSS6, promoter and the ubiquitin, Ubi3, polyadenylation signal. Analysis of SGA metabolites in selected transgenic tubers revealed a dramatic decrease in the accumulation of α-chaconine and α-solanine. This decrease was compensated by an increase in β-solanine and β-chaconine with minor accumulation of α-SGAs. These results allowed the identification of the function for SGT3 as the β-solanine/β-chaconine rhamnosyl transferase, the terminal step in formation of the potato glycoalkaloid triose side chains. [Copyright &y& Elsevier]

Abstract: To provide tools for breeders to control the steroidal glycoalkaloid (SGA) pathway in potato, we have investigated the steroidal alkaloid glycosyltransferase (Sgt) gene family. The committed step in the SGA pathway is the glycosylation of solanidine by either UDP-glucose or UDP-galactose leading to α-chaconine or α-solanine, respectively. The Sgt2 gene was identified by deduced protein sequence homology to the previously identified Sgt1 gene. SGT1 has glucosyltransferase activity in vitro, but in vivo serves as the UDP-galactose:solanidine galactosyltransferase. Two alleles of the Sgt2 gene were isolated and its function was established with antisense transgenic lines and in vitro assays of recombinant protein. In tubers of transgenic potato (Solanum tuberosum) cvs. Lenape and Desirée expressing an antisense Sgt2 gene construct, accumulation of α-solanine was increased and α-chaconine was reduced. Studies with recombinant SGT2 protein purified from yeast show that SGT2 glycosylation activity is highly specific for UDP-glucose as a sugar donor. This data establishes the function of the gene product (SGT2), as the primary UDP-glucose:solanidine glucosyltransferase in vivo. [Copyright &y& Elsevier]

Steroidal glycoalkaloids (SGAs) are secondary metabolites of Solanaceous plants. Two predominant glycoalkaloids, α-chaconine and α-solanine are produced in potatoes. An antisense transgene was constructed to down-regulate glycoalkaloid biosynthesis using a potato cDNA encoding a sterol alkaloid glycosyltransferase (Sgt1). Introduction of this construct into potatoes resulted in some lines with an almost complete inhibition of α-solanine accumulation. This inhibition was compensated by elevated levels of α-chaconine and resulted in wild type total SGA levels in the transgenic lines. In vitro assays with the recombinant SGT1 isolated from yeast demonstrated that Sgt1 encodes an enzyme capable of both glucosyltransferase and galactosyltransferase activity with a preference for UDP-galactose as the sugar donor. Together this data confirms SGT1''s role in vivo as the solanidine:UDP-galactose galactosyltransferase. [Copyright &y& Elsevier]