Beckles - Biotechnology Postharvest Qualityucce.ucdavis.edu/files/datastore/234-1601.pdfGenetic...
Transcript of Beckles - Biotechnology Postharvest Qualityucce.ucdavis.edu/files/datastore/234-1601.pdfGenetic...
Biotechnology and Postharvest Quality
Diane M BecklesDepartment of Plant SciencesUniversity of California-Davis
[email protected]://www.plantsciences.ucdavis.edu/beckles/beckles_index.html
Biotechnology
A set of tools (molecular) used to modify the genetic makeup of an organism so that: It produces a new product The product perform new function(s)
Postharvest Quality The factors that ensure maximum income for
producers as well as meeting the nutritional and aesthetic needs of the consumer after horticultural crops are harvested. Producers and consumers often have opposing wants
Consumers
Texture
Flavour
Aroma
Sweetness
Acidity
Color
Appearance
Nutrition Producers
Shelf-life
Chilling-tolerance
MicrobialcontaminationBrowning
Firmness
Diseaseresistance
Genotype
The genetic composition of an organism. Contains all of the information that
determines final characteristics.
Postharvest traits are due to the interaction of the environment and genotype
Identical genotype Different environment
Different genotype Same environment
Normal tomato
rin: ripeningmutant
25°C
Ripened fruit
Chilling injury
25°C
5°CNormal tomato
Biotechnology can be used to change the gene composition and create genetically engineered organisms (GEOs) with enhanced traits -including those with improved postharvest qualities.
Power of biotechnology
Desirable traits for improving Postharvest Quality of produce
Improved flavour, texture, colour Long storage Delayed ripening Enhanced nutrition and health benefits Better food processing Nutraceuticals
MYTH: Genetic modification of crop plants is new
False: All crop plants have been genetically modified
Biotechnology is another (more sophisticated) tool used to genetically modify crop plants
DomesticationScience-based Selective breeding
Mutagenesis breedingEmbryo culture
Biotechnology and geneticengineering
Sophistication of technology
Genetic modification of crop plants
1. Domestication. 2. Selective breeding. 3. Mutagenesis breeding. 4. Embryo culture. 5. Biotechnology.
Domestication: cultivated vs wild tomato
Wild Modern cultivated tomato tomato
From Frary et al., 2000 Science
Wild banana vs modern cultivars
Wild banana with seeds Cultivated banana- sterile
Genetic modification of crop plants
1. Domestication 2. Selective breeding 3. Mutagenesis breeding 4. Embryo culture 5. Biotechnology
2. Selective breedingSolanum
lycopersicon
Solanumperuvianum
Wild species has resistance to nematodes
Percent of “wild” genes 50%
25%
12.5%
Using the wild tomato species as a source of genes for nematode resistance
Six or more generations of backcrosses to the cultivated parent, selecting for resistance at each generation
6.25%
3.125%
1.5%
0.75%Kent Bradford, Depart Plant Sciences, UC Davis
Selective breeding
Cauliflower and broccoli were derived from the same genetic ancestorBrassica oleracea
California Agriculture vol 58 #2; http://CaliforniaAgriculture.ucop.edu
Genetic diversity
From : “What is Biotechnology?” by Dr. Peggy Lemeaux; University of California, Berkeley
Genetic modification of crop plants
1. Domestication 2. Selective breeding 3. Mutagenesis breeding 4. Embryo culture 5. Biotechnology
3. Mutational breeding
Radiation breeding: Texas red grapefruit variety Rio RedDeveloped by mutation of Ruby Red. There are more than 2000Crops which were produced by radiation
Chrispeels and Sadava, 2002 Plant, Genes and Crop Biotechnology; ASPB
Genetic modification of crop plants
1. Domestication 2. Selective breeding 3. Mutagenesis breeding 4. Embryo culture 5. Biotechnology
4. Embryo rescue-laboratory culture of plant embryos
Inter-species crossing Embryo cannot naturally develop into a mature plant Embryo must be dissected and nurtured on media
Fruits cultivated by embryo rescue
Early-ripening stone fruit varieties
All seedless grape varieties
Small immature embryos that must be cultured individually in test tubes to grow a hybrid seedling.
Genetic modification of crop plants
1. Domestication 2. Selective breeding 3. Mutagenesis breeding 4. Embryo culture 5. Biotechnology
5. Biotechnology
Manipulations done at molecular level. Specific genes may be changed. Gene function usually understood. Genes can be transferred between species.
Tenets
All living organisms characteristics determined by DNA.
DNA code broken – functions known for most DNA sequences.
DNA is fundamentally the same in all organisms DNA should be interchangeable between species.
Gene identification
Genes encoding important traits Extended shelf-life Insect, disease resistance Uniform ripening Increased sugars Enhanced Aroma Antioxidants
Gene manipulation
Gene expression in crop is altered in various ways Suppression (a deleterious gene) Over-expression (favourable gene) Modification (enhancing a characteristic) Transgene expression (introducing new function)
How genetic engineering of plants works
A gene of known function in plant is identified (e.g. gene controlling fruit ripening) and isolated.
The gene must be stably incorporated into plant.
The gene must be heritable.
Genes are introduced into the plant using bacterial plasmid as vectors
Gene to be suppressed or overexpressed
Plasmids are circular molecules of DNA found in bacterial cells. They confer survival to antibiotics
How to get the DNA into the plant
Agrobacterium tumesfaciens (more precise).
Particle bombardment (random insertion of genes).
Regeneration from single cell to whole plant
drawing by Celeste Rusconi, © Regents of the Univ. California
Biotechnology & Postharvest biology Can we use these tools to improve the postharvest
quality of horticultural crops?
Adel Kader, Dept Plant Sciences, UC Davis
Yes…..maybe
Transgenic papaya resistant to papaya ringspot virus
California Agriculture vol 58 #2; http://CaliforniaAgriculture.ucop.edu
Non-transgenic Transgenic
Transgenic plums resistant to plum pox virus
Non-transgenic fruit Transgenic fruit
California Agriculture vol 58 #2; http://CaliforniaAgriculture.ucop.edu
Novel ornamentals
Florigene Moonshadowtransgenic carnations; produces intense blue-violet colour.
Flavr Savr tomatoes – extended shelf-life
Chrispeels & Sadava, 2002 Plant, Genes and Crop Biotechnology; ASPB
Uniform/delayed ripening
Transgenic tomatoes with altered ethylene production.
Harvest can be done every 2 days instead of twice a day.
Fruit stays in field longer without deteriorating.
Non-transgenic Transgenic fruit4-colours 2-colours
From : “What is Biotechnology?” by Dr. Peggy Lemeaux; University of California, Berkeley
Delayed softening/ripening in transgenic apples
Dandekar et al (2004) Transgenic Research 13 373-384
Transgenic
Transgenic
Transgenic
Control
What’s the problem with GE?
Polarizing and disparate views of the technology
GE crops – harmful to living creatures?
© Drawing by Nicholas Eattock, Dept Plant Sciences UC Davis
GE crops will create monsters
© Drawing by Nicholas Eattock, Dept Plant Sciences UC Davis
GE crops – a cure-all
© Drawing by Nicholas Eattock, Dept Plant Sciences UC Davis
GE crops - bountiful harvests
© Drawing by Nicholas Eattock, Dept Plant Sciences UC Davis
Public perception of GE
FACTOR Coerced vs. voluntary
Industrial vs. natural
Dreaded vs. not dreaded
Unknowable vs. knowable
Untrustworthy rather than trustworthy
Unresponsive vs. responsive management
EXAMPLE Everyone must eat GE food if
unlabeled. Big multinational hybrid vs. landraces.
Unknown risks (cancer?)
Only experts know the risk, and they debate
Multinational vs. small farmer
Open vs. arrogant and remote
Chrispeels and Sadava, 2002 Plant, Genes and Crop Biotechnology; ASPB
Getting to the truth about GE crops
Facts vs fiction about GE crops
Myth GE plants will create superweeds.
FactGE plants will create weeds just like most crop plants; cannot determine the impact on the environment.
Facts vs fiction about GE crops
MYTH GE foods have genes and normal food do not.
FACT All living organisms have genes.
Facts vs fiction about GE crops
MYTH Almost all crops are GE.
FACT The cost of meeting regulatory requirements ($20-30 million per crop)
limits the number of GE crops commercialized. This
is especially true of horticultural crops (only 2-3 exist).
Facts vs fiction about GE crops
MYTH There will be animal genes in fruit and vegetables.
FACT Technically possible to accomplish this ……..but no company would commercialize
a product which would be reviled by the consumer – bad business!
Facts vs fiction about GE crops
MYTH GE food are unnatural.
FACT So are all of the foods (including fruit and vegetables we eat
today!).
Facts vs fiction about GE crops
MYTH When you transform plants you do not know what is happening.
FACT With transgenics you introduce a single gene, with traditional
breeding you may introduce hundreds of unknown genes.
Genetic re-arrangement in selective cross breeding vs GE
1. What’s for dinner – Genetic engineering from the lab to your plate.”2. Gepts, P. (2002) Crop Science 42:1780-1790
Facts vs fiction about GE crops
MYTH Farmers in developing countries will not benefit.
FACT Governments of many developing countries have adopted technology
pioneered by multinationals.
http://www.fao.org/biotech/inventory_admin/dep/default.asp
Facts vs fiction about GE crops
MYTH GE food will contain allergens and toxins
FACT (i) We consume 10,000 toxins daily. Coffee contains 1000 toxins, of
27 tested 19 were carcinogens.
(ii) Peanuts, brazil nuts, wheat cause serious allergic reactions
Facts vs fiction about GE crops
MYTH Transgenes will move from plants to humans once ingested
FACT No-one has shown that genes move from ingested food into
human cells
Facts vs fiction about GE crops
MYTH GE crops are not adequately tested or regulated
FACT There are greater testing requirements for GE crops compared to traditional crops
http://usbiotechreg.nbii.gov/lawsregsguidance.asp
Substantial Equivalence
Numerous scientific reviews have concluded that food created by genetic engineering presents no greater dangers than genetic changes introduced by other methods.
The product should be evaluated, not the method by which it is produced.
Bradford et al., (2005) Nature Biotechnology 23: 439-444
Limits to application of biotechnology to Horticultural crops
Economies of scale. Expensive to apply to niche crops and cultivars
Technologies not sufficiently developed for individual crops. Long generation times - not tractable.
For tree crops – use grafting!Transgenic walnut shoot grafted ontocontrol rootstock in B while crowngalldevelops in non-transgenic shoot graftA
Escobar et al (2001) Proc Natl Acad Sci USA. 98:42
Limits to application of biotechnology to Horticultural crops
Several postharvest traits are complex Multigenic; strongly affected by the environment
Public resistance to the idea. More intimate ‘association’ with fruit and
vegetables than maize or soybean products
Gene transfer to non-GE crops. Disturbing evidence that native landraces in Mexico
pollinated by GE crops*
Positional Effects. Disruption of native genes at the site where the construct
is inserted**
Monopolization/Concentration power by seed companies
They determine the traits worthy of investment. Humanitarian interests may not be prioritized.
Unresolved Issues
*http://www.plantsciences.ucdavis.edu/gepts/mec_3993_LOW.pdf**Gepts, P. (2002) Crop Science 42:1780-1790
Real risks of common activities from actuary data
Number of deaths divided by number of people engaged in the activity fromChrispeels & Sadava, 2002 Plant, Genes and Crop Biotechnology; ASPB
Summary
Biotechnology holds great potential for improving postharvest biology of horticultural crops
No technology is risk-free or is absolutely safe Genetic modification of crops is not new Today we have better, more sophisticated tools to
achieve crop improvement Scientists must adequately address food and
environmental risks as well as public concerns about the technology
Bibliography/Sources
Chrispeels and Sadava, 2002 Plant, Genes and Crop Biotechnology; ASPB Bradford KJ & Alston, J. (2004) California Agriculture vol 58(2):84-85
http://CaliforniaAgriculture.ucop.edu Bradford et al (2004) California Agriculture 58(2):68-71 http://CaliforniaAgriculture.ucop.edu Clark et al (2004) California Agriculture 58(2): 89-98 http://CaliforniaAgriculture.ucop.edu Lemaux, P. (1998) What is biotechnology?
http://ucbiotech.org/resources/biotech/slides/biotech.html retrieved 5/20/03 “What’s for dinner – Genetic engineering from the lab to your plate.”
http://www.foodsafetynetwork.ca/biotechres/newpdfs/pg9-18.pdf retrieved 5/20/03
Prakash C.S. : Agricultural Biotechnology and Food Security”www.agbioworld.org retrieved 5/20/03
Bibliography/Sources (cont’d)
Bradford et al., (2005) Nature Biotechnology 23: 439-444 Dandekar et al (2004) Transgenic Research 13: 373-384. Frary et al. (2000) Science 289. no. 5476, pp. 85-88 “Introduction to Genetic Analysis” Anthony Griffiths 9th Ed (2008). W.H.Freeman
Publishers Gepts, P. (2002) Crop Science 42:1780-1790 US Regulatory Agencies Unified Biotechnology website http://usbiotechreg.nbii.gov/lawsregsguidance.asp Cartoons by Nicholas J. Eattock, Dept Plant Sciences, UC Davis