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New technologies in animal and plant breeding Helen Sang University of Edinburgh “Genome editing” • DNA is packaged into chromosomes • Humans have 1.8metres of DNA • Each chromosome is a linear array of genes, each of a unique sequence “Genome editing” Genome editing involves the use of “molecular scissors” to identify a specified gene sequence and then cut the gene at the target site “Genome editing” The DNA at the cut site may be replaced with a very short stretch of new DNA CRISPR: sequence-specific editing • • • • CRISPRs are the most recently developed molecular scissors CRISPRS are very efficient in finding the target sequence and cutting DNA Cut DNA may be repaired but not precisely, causing a novel mutation Cut DNA may be repaired using a different sequence, introducing a precise genetic change Mutation of a target gene: resistance to PRRS a major viral disease of pigs University of Missouri and Genus PLC Mutation of a specific gene, required for the infection of pigs by PRRS virus, results in resistance to infection Gene editing in a Brassica crop: pod shatter in oil seed rape a b c Wild type Edited d Wild type Edited A single mutation in a model brassica species stops pod shatter Introduction of a similar mutation in oil seed rape should greatly Lawrenson et al. Genome Biology 2015 reduce losses of seed Replicate a natural mutation in different breeds Recombinetics Beef cattle are hornless, the polled mutation; the majority of dairy cattle have horns that are removed in calves. Gene editing has been used to make dairy cattle hornless. Move genetic variation between species: African Swine Fever virus Bruce Whitelaw and colleagues, The Roslin Institute Aquaculture: main source of fish protein globally, Require source of omega3 fatty acids in diet Wild fish mainly take up omega3 LC-PUFAs via the food chain Primary producers of omega-3 LCPUFAs are algae Farmed fish has to be fed with omega-3 LCPUFAs Need a sustainable source of omega-3 LCPUFAs Reduction fisheries are limiting growth of aquaculture Can an oil seed crop be genetically altered to form a source of omega3 fatty acids for farmed fish food? http://www.rothamsted.ac .uk/camelina-2015 Nitrogen availability limits crop yields Legumes are the prototype for self-fertilising crops Aim: genetically alter cereals to fix nitrogen, adopting the mechanisms used by legumes e.g.peas https://www.jic.ac.uk/ New breeding technologies using molecular techniques • Simple gene mutation: equivalent mutations could exist “naturally”; much faster than breeding • Move gene variant between breeds: avoid loss of genetic merit; much faster than breeding • Move gene variants between species; cannot be achieved by breeding • Introduce novel genes not present in particular species e.g. blight resistance; may involve introduction of new DNA sequences • Introduce novel genetic pathways to enhance qualities; complex combination of very small genetic changes and inroduction of new gene sequences Parallel increase in knowledge of genome sequences/gene structure/gene function in crops and farmed animals (and their diseases) results in opportunities to use GE to increase productivity faster