ABSTRACT. Genome or gene editing includes several new techniques to help scientists precisely modify genome sequences. The techniques also enables us to alter the regulation of gene expression patterns in a pre-determined region and facilitates novel insights into the functional genomics of an organism.Emergence of genome editing has brought considerable excitement especially among agricultural scientists because of its simplicity, precision and power as it offers new opportunities to develop improved crop varieties with clear-cut addition of valuable traits or removal of undesirable traits. Research is underway to improve crop varieties with higher yields, strengthen stress tolerance, disease and pest resistance, decrease input costs, and increase nutritional value. Genome editing encompasses a wide variety of tools using either a site-specific recombinase (SSR) or a site-specific nuclease (SSN) system. Both systems require recognition of a known sequence. The SSN system generates single or double strand DNA breaks and activates endogenous DNA repair pathways. SSR technology, such as Cre/loxP and Flp/FRT mediated systems, are able to knockdown or knock-in genes in the genome of eukaryotes, depending on the orientation of the specific sites (loxP, FLP, etc.) flanking the target site. There are 4 main classes of SSN developed to cleave genomic sequences, mega-nucleases (homing endonuclease), zinc finger nucleases (ZFNs), transcriptional activator-like effector nucleases (TALENs), and the CRISPR/Cas nuclease system (clustered regularly interspaced short palindromic repeat/CRISPR-associated protein). The recombinase mediated genome engineering depends on recombinase (sub-) family and target-site and induces high frequencies of homologous recombination.

Genome editing in agriculture and food is leading to new, improved crops and other products. Depending on the regulatory approach taken in each country or region, commercialization of these crops and products may or may not require approval from the respective regulatory authorities. This paper describes the regulatory landscape governing genome edited agriculture and food products in a selection of countries and regions.

SummaryThis paper reviews the history of the federal regulatory oversight of plant agricultural biotechnology in the USA, focusing on the scientific and political forces moulding the continually evolving regulatory structure in place today. Unlike most other jurisdictions, the USA decided to adapt pre-existing legislation to encompass products of biotechnology. In so doing, it established an overarching committee (Office of Science and Technology Policy) to study and distribute various regulatory responsibilities amongst relevant agencies: the Food and Drug Administration, Environmental Protection Agency and US Department of Agriculture. This paper reviews the history and procedures of each agency in the execution of its regulatory duties and investigates the advantages and disadvantages of the US regulatory strategy.

Heat stress can detrimentally affect the reproductive capacity of many plants. The effect of a 7 or 14 d heat stress on flowering, seed set, pollen viability and germinability of flax ( Linum usistatissimum L.) was assessed under growth chamber conditions. An incremental (2 ∞ ∞ ∞ ∞ C/h), cyclical (daytime high 40 ∞ ∞ ∞ ∞ C and night-time low 18 ∞ ∞ ∞ ∞ C) heat stress was applied 12 d after the initiation of flowering. Although flower formation in flax was not affected by heat stress, boll formation and seed set were reduced with onset of the heat stress. On removal of heat stress the stressed plants showed a compensatory response, flowering and producing bolls at a greater rate than the control plants. Heat stress significantly prolonged flowering by 17 d. Boll weight and seed weight were reduced with heat stress and the number of malformed, sterile seed increased three-fold after 14 d of heat stress. Pollen viability and appearance were negatively affected after 6 and 10 d of heat stress, respectively. Pollen germinability decreased by the sixth day of heat stress, with no pollen germinating by the tenth day. Effects of heat stress on pollen viability and germinability alone, which did not occur until after the sixth day of the stress, could not account for the decreased boll formation due to heat stress in flax. These observations suggest that a combined effect of heat stress on both pollen and ovules contributes to decreased boll formation and seed set in flax.

Agrobacterium tumefaciens carrying a disarmed Ti-plasmid vector containing a chimeric NPT-ll gene and a mutant acetolactate synthase gene (conferring resistance to the herbicide chlorsulfuron) from Arabidopsis was used to transform flax (Linum usitatissimum) hypocotyl tissue. Transgenic regenerants were recovered from the inoculated tissue and were tested for expression of the foreign genes by leaf callus assays on kanamycin and on chlorsulfuron. Transgenic plants were grown to maturity; selfed progeny were similarly tested to determine segregation pattern for the novel genes, and some were grown in chlorsulfuron containing soil. Lines from two major commercial cultivars express chlorsulfuron resistance in greenhouse tests.