Download Helen Sang presentation

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
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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