Download Hopes for the future: new breeding technologies Helen

Hopes for the future:
new breeding technologies
Helen Sang
The Roslin Institute
University of Edinburgh
www. bbsrc.ac.uk
“Genome editing”
• DNA is packaged into chromosomes
• Humans have 1.8metres of DNA, wheat 5X longer
• Each chromosome is a linear array of genes, each of a unique sequence
“Genome editing”
Genome editing:
“molecular scissors” identify a specified gene sequence and then cut
the DNA
“Genome editing”
The DNA at the cut site may be replaced with a very short stretch of new DNA:
making a specific change in a gene is possible
CRISPR: sequence-specific editing
• CRISPRs:most recently developed molecular scissors
• CRISPRS very efficient in finding the target sequence
and cutting DNA
• Cut DNA may be repaired causing a novel mutation
• Cut DNA may be repaired,
introducing a precise genetic change
Powdery mildew in wheat: CRISPR
mutation of TaMLOabd
Yanpeng Wang, Xi Cheng,Qiwei Shan,Yi Zhang,Jinxing Liu,Caixia
Gao& Jin-Long Qiu Nature Biotechnology 32, 947–951 (2014)
Mutation of a target gene: resistance to
PRRS a major viral disease of pigs
University of Missouri and Genus PLC
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 reduce losses of seed
Lawrenson et al. Genome Biology 2015
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 in potatoes; may involve introduction
of new DNA sequences
• Introduce novel genetic pathways to enhance qualities;
complex combination of very small genetic changes and
introduction 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 and in novel ways
BUT!!!!!
• What are the most useful/practical
applications?
• How will genome edited crops be
regulated?
• Will they be accepted by consumers?
• Will more complex combinations of
GE and GM become accepted?
More information:
Wendy Harwood [email protected]
https://www.jic.ac.uk/
Matina Tsalavouta
[email protected]
http://www.rothamsted.ac.uk/
Replicate a “natural mutation” in
different breeds
Recombinetics
• Beef cattle are hornless, the polled
mutation
• majority of dairy cattle have horns that
are removed in calves.
• Gene editing has been used to make
dairy cattle genetically hornless