Background

China is one of the biggest agricultural countries over the world. But in our country, farmers still have a lot of problems to deal with. Drought, pests, water pollution, weeds and so on. These problems cause damage to the agriculture industry. So we want to do some help.

We focused on the weeds problem. Usually, farmers use herbicides to kill the weeds. However, the abuse of herbicides in our country have caused a series of secondary prblems. One of them is that the weeds have the resistant to the herbicides. As we all know, if we always use one kind of antibiotic,the bacteria will become drug-fast. So do the weeds. If famers use only use one kind of herbicide, as the time goes by, the weeds will become herbicide resistant. And farmers have to raise the dose to kill them. However, the more dose farmers raise, the stronger the weeds will be. It is a vicious circle. What’s more, raising the dose will cause many other environmental problems. It will raise the poisonous residue and do harm to animals and human. Let’s use the antibiotic as the example again. If we find that the bacteria has the resistant to antibiotic A, then we will antibiotic B to kill it because there is very few chance that the bacteria have double resistance at the same time in the wild. Similarly, if we use two or more kinds of herbicides the resistant weeds will be killed easily. Also the mix use of herbicides can help us solve many other probelems. So, obviously, Creating a genetically modified crop which is resistant to more than one kind of herbicide enable us to utilize a combination of several herbicides in agriculture.So, obviously, Creating a genetically modified crop which is resistant to more than one kind of herbicide enable us to utilize a combination of several herbicides in agriculture.

How did we come up with it?

Unlike the microrganism, co-expression of diffrent kinds of genes is hard to achieve for plant(without a counterpart of operon ) . In our project we choose 2A to serve as a linker between 2 proteins. 2A is a short peptide containing 20 contiguous amino acids. And it has an interesting feature.When placed between 2 genes using a single ORF, during the translation process, the attachment between 19th and 20th amino acid will break. Then the translation process will continue. That means 2A provides us a potential approach to realize gene co-expression.

The major advantages of using the 2A system in the construction of multicistronic vectors are(i)its small size(54-174bp)compared to IRESes,that coexpression of proteins linked by 2A is independent of the cell type(since structurally highly conserved amongst the eukaryotic ribosomes,structurally highly conserved amongst the eukaryota),and(iii)that multiple 2As may be used, the activity of each being completely independent.

Our project create 4 genetically modified Arabidopsis thaliana, and categorized them into 2 combinations, one being BAG & GAB, the other BGT & TAB(B=BAR G=GAT T=tfdA, they're 3 common herbicide resistant genes. A=2A linker). We hope 2A will help with the puzzle of herbicide resistance in agriculture.

Our experiment

We want to do more

Bio safety

We have plans to make further modifications to the system, adding a toxic gene in between the two target genes in case of super weed caused by genetic drift. And the application of this vector is restrained within the crops that won't be disturbed by the toxin. In our bettered system, only one herbicide gene is at the risk of drifting because if more genes were to drift into another species, it would definitely include the toxic gene and disrupt the normal life of weeds and thus can't live. The genetic drift rate of each gene is at the end of the day very low, and present prevention methods are proven to be efficient. With our modification, this problem is kept at a even smaller scale.

"Super Crop"

We aims to create a kind of crop that is resistant to different kinds of stress and having other good qualities. Bacillus thuringiensis Crystal (Cry) and Cytolitic (Cyt) protein families are a diverse group of proteins with activity against insects of different orders. Co-expressing different pesticidal protein in crops using 2A can help create insect-resistant crops.

Also transimitting the LEA protein family can improve the cold-resistant ability of plants. SOS 1,2,3 cooperate to regulate ion homeostasis under salt stress. SOS family is also under consideration to resist salt stress. We also want to transform the metabolic pathways. C4 photosynthesis is a series of anatomical and biochemical modifications to the typical C3 pathway that increases the productivity of plants in warm, sunny, and dry conditions. Co-expressing key enzyme of C4 plant in C3 plant may help to modify the classical C3 pathway.

References

［1］ Dill GM, Cajacob CA, Padgette SR. Glyphosate-resistant crops ：adoption, use and future considerations. Pest Manag Sci, 2008, 64（4）:326-331.

［2］Abdelhak El Amrani, Abdellah Barakate, Barak M. Askari, Xuejun Li, Alison G. Roberts,Martin D. Ryan, and Claire HalpinCoordinate Expression and Independent Subcellular Targeting of Multiple Proteins from a Single Transgene. Plant Physiology, May 2004, Vol. 135, pp. 16–24,