3rd blog. Example Cisgenesis

Cisgenic apples

The generation of cisgenic crops is limited between apples, barleys and potatoes.

Cisgenesis is useful in apples because of the introduction a particular resistance gene that confers resistance to some diseases, for example to fire blight, which is caused by a Gram-negative bacterium Erwinia amylovora, one of the most important pome fruit pathogen worldwide.[2] However, the introduction of a resistance from a wild source takes between 20 to 50 years until a cultivar with fruit of marketable quality can be released. [1]

In Switzerland lots of tonnes of apples are produced annually, most of them generated by ‘’golden Delicious’’ and ‘’Gala’’. Due to the pathogen, lots of trees were eradicated and because of that the use of streptomycin started. However, some strains of that pathogen had become resistant to this antibiotic, and this is why genetic engineering is a good way as a second strategy to produce resistant fireblight apple trees.

Nowadays, there are three methods that have been successfully applied producing trees. One of them avoid the use of any source than the apple. Other one uses the excision of selectable marker genes, and the last is done by the use of T-DNAs. [3]

Literature:

[1] Kost, T.D., Gessler, C., Jänsch, M., Flachwosky, H., Patocchi, A., & Broggini, G. A. L. (2015) Development to the first cisgenic apple with increased resistance to fire blight. PLoS One; 10(12):e0143980.

[2] Gusberti, M., Klemm, U., Meier, M. S., Maurhofer, M. & Hunger-Glaser, I. (2015) fire blight control: the struggle goes on. A comparison of different fire blight control methods in Switzerland with respect to biosafety, efficacy and durability. Int J Environ Res Public Health; 12(9) : 11422-11447.

[3] Krens, F. A., Schaart, J. G., van der Burgh, A. M., Tinnenbroek-Capel, I. E. M, Groenwold, E., Kodde, L. P., Broggini, G. A. L., Gessler, C. & Schouten, H. J. (2015) Cisgenic apple trees; development, characteritzation and performance. Front Plant Sci; 6:286.

Cisgenic plants

1.       In your own words, but using the correct scientific terms, explain one method for producing a cisgenic plant.

A cisgenic plant is described as a crop plant that has been genetically modified with one or more genes isolated from a crossable donor plant [2].  It combines traditional techniques with modern biotechnology and dramatically speeds up the breeding process. This allows plant genomes to be modified while remaining plants within the gene pool. Therefore, cisgenic plants should not be assessed as transgenics for environmental impacts.

One method is electro-transfection, which is the application of strong electric field pulses to cells and tissue is known to cause some type of structural rearrangement of the cell membrane resulting in a temporary increase in porosity and providing a local driving force for ionic and molecular transport through the pores.[4]

2.       How is this process similar and how is it different from producing a transgenic plant?

Cisgenesis is described as specific alleles/genes in the breeder’s gene pool are introduced into new varieties without the accompanying linkage drag (co-transfer of DNA sequences that are linked to the gene of interest) which occurs in conventional breeding. In contrast, a transgenic plant receives gene(s) from a non-plant organism, or from a donor plant that is sexually incompatible with the recipient plant. [2].  

3.        How is the result of the cisgenic breeding process different from a classically bred plant? How is it similar?

In traditional breeding, obtaining desired traits is painstakingly slow and one challenge is the low affinity between wild and cultivated varieties. Techniques such as embryo rescues, cross bridges and somatic cell hybridization help overcome this obstacle. [2]

Compared with induced translocation and introgression breeding, cisgenesis is an improvement for gene transfer from crossable plants. The similarity of the genes used in cisgenesis compared with classical breeding is a compelling argument to translocation breeding, the insertion site of the genes is a priori unknown, as it is in cisgenesis. [1]

4.       What are the safety concerns of cisgenic plants? Are they different in transgenic plants? Are they different from classically bred plants?

Cisgenesis is not any different from traditional breeding or that which occurs in nature. There is no environmental risk evoked and release of cisgenic plants into the environment is as safe as that of traditionally bred plants, so they have the same hazards. However, the transformation techniques used in cisgenesis and transgenesis are the same, so they have similar risk linked to transfer technology. [2]

5.       In your opinion, is it correct to treat cisgenic plants like transgenic plants?

Now, cisgenic plants fall under regulations designed for transgenic organisms, possibly because there have not yet been any applications for the approval of the deliberate release of cisgenic plants into the environment [3] .

In my opinion, cisgenic plants are fundamentally different from transgenic plants, therefore they should be treated differently under GMO regulations.

Literature:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1525145/ [3]

http://www.ncbi.nlm.nih.gov/pubmed/17383037 [1]

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4127943/ [2]
http://scialert.net/fulltext/?doi=biotech.2008.385.402 [4]

Plant biotech blog entry. Micropropagation process.

MICROPROPAGATION PROCESS

Plant tissue culture is a collection of techniques to grow plant cells, tissues or organs under sterile conditions. It is also known as in vitro culture. An example is micropropagation. It is the production of whole plant from small sections of plant such as stem tip, node, meristem, embryo or even a seed.

This process works because plants, has the ability to reproduce the whole plant from a single cell, this is called totipotency (ability of a single cell to express the full genome of in the cell to witch it gives rise by cell division) and an asexual reproduction.

In order to start a micropropagation process, tissue is taken from the shoot apex of plant. Then, you put the tissue on nutrient agar gel with auxin (hormone), and something starts growing, which is called callus (soft tissue composed of unorganized and undifferentiated group of cells). Callus can be transferred to agar gel with cytokinin or gibberellins to stimulate root / shoot growth. Finally, you should transfer the plantlets into sterilized soil for hardening under greenhouse environment.

Some advantages of micropropagation process:     

• Bulk up new varieties more quickly.
• Produces species that are hard to grow in other ways.
• Genetic modification can be made in a small number of plants which then give. thousands of plants carrying the desired change.
• Tiny plants can be stored until needed.
• Produce large numbers of rare plants reduce cost and don’t need to take from wild.
• Plants can be produces at any time of the year.

Literature:

http://theagricos.com/tissue-culture/micropropagation/stages-of-micropropagation/

http://www.uky.edu/Ag/Horticulture/Geneve/teaching/plantpropwebpages/micropropagation/tctypesmicropropagation.pdf

https://www.youtube.com/watch?v=hgOqTyiI_30