biotechnology - using an organism to make a product, …or using advanced methods to study an...
TRANSCRIPT
biotechnology - Using an organism to make a product, …or using advanced methods to study an organism
GMO - Genetically Modified Organism
Transgenic - describing material where a gene from one organism has been transferred into another
Dr. Ken KorthDepartment of Plant
Pathology
University of Arkansas, Fayetteville
Two applications of biotechnology for crop plants…
1. Using techniques to identify desired plants, for example through Marker-Assisted Selection. -- to speed up the selection process in breeding
programs
-- to identify and track genes that might have minor effects (quantitative trait loci, QTL)
2. Through the introduction of novel genes in crop plants (GMOs). -- as a research tool to identify gene
function
-- to develop novel plants for release
Each cell in a rice plant has about 400 million base pairs of DNA.
Double helical structure of DNA
G pairs with CA pairs with T
NucleusDNA
RNA
Transcription
Processed RNA
RNA
Protein
Translation
Enzymes, structural proteins, signaling factors, hormones, energy storage, metabolism
DNA provides the “code” thatdetermines which proteins are made
Marker-Assisted Selection
1. A first step is to identify DNA sequences associated with some trait – these can originate is any variety of interest.
(Image from Goff and Salmeron, Sci Amer. 2004)
Marker-Assisted Selection
2. After crossing with an elite cultivar, progeny that carry the desired marker can be identified – at a very young age.
(Image from Goff and Salmeron, Sci Amer. 2004)
(Image from Goff and Salmeron, Sci Amer. 2004)
3. Genes or sequences can be tracked through DNA fingerprinting techniques.
Marker-Assisted Selection
(Image from Goff and Salmeron, Sci Amer. 2004)
4. Genes or sequences of interest can be combined into new cultivars using traditional crossing techniques.
Marker-Assisted Selection
from Liu, et al., MPMI (2004), 17:1146
# of defense response genes in a plant line
Am
ou
nt
of
dis
ease
Five genes that respond to blast infection were first identified through basic molecular studies…
An example of the utility of molecular applications:
from Liu, et al., MPMI (2004), 17:1146
# of defense response genes in a plant line
Am
ou
nt
of
dis
ease
Each gene by itself has a minor effect, but when combined lead to high levels of resistance – presence of the genes is determined via molecular analysis
An example of the utility of molecular applications:
Some potential uses for transgenic plants…….
• enhanced insect and herbicide resistance
• a research tool to identify gene function
• enhanced pathogen resistance
• foods with enhanced nutritional value
• enhanced salt or drought tolerance
• “farmaceuticals” production
A crown gall tumor on tomato.The stem was wounded with a needle carrying Agrobacterium tumefaciens--this photo was taken one month after inoculation
Agrobacterium is a plant pathogen—it can transfer DNA into plant cells
Callus tissue (undifferentiated cells) is placed on selective media--only cells with the introduced DNA should survive
Closeup of a clump of callus onselective media--sectors of surviving cells are growing and look healthy--deadand dying cells look brown.
Selection for transformed cells is generally used.
By changing levels of plant hormones in the media, callus is induced to form plant shoots, then shootsare transferred to new media and induced to form roots.
Callus can be regenerated to form a whole plant
(photos of rice tissues from Yinong Yang)
Pick single colony and grow cells
Inoculate planttissue and regeneratewhole plant on selective media
Agrobacterium plant transformation…
Introduce DNA ofinterest into bacteria
Vitamin A (trans-retinol) deficiency:
In Southeast Asia, approximately 5 million children developxeropthalmia (impaired vision) each year.
0.25 mil eventually go blind
correlated with diarrhea, respiratory diseases, measles
According to UNICEF, Vitamin A supplements could prevent 1- to 2-million childhood deaths per year
The biochemistry of Golden Rice…
The protein in this step adds the double bonds
The protein that performs this step modifies the ends…
A recent improvement has led to Golden Rice that produces levels of -carotene over 20X higher than the original
(Paine, et al., (2005) Nature Biotech., 4:482)
Normal rice Original Improved
Golden Rice
New techniques in plant biology are leading to…
• Improved tools for plant breeders and biologists
• The ability for wide transfer of genes
• Complex issues
Current Biotech/Genomics applications in rice
•Although transgenic (“GMO”) rice is being grown in other parts of the world (China, Iran, ?), it is not currently being commercially grown in the U.S.
•The complete sequence of the rice genome is known. This information can make it easier to identify and characterize specific genes of interest, not only in rice but also in related species (e.g., corn, wheat, barley, etc…)