Greatest ideas are always found in one’s own backyard. Somewhat similar happened to this year’s iGEM team ICT Mumbai. India being a majorly agriculture dependent country, we decided to make lives of our farmers better as a result of our project. The fate of almost all agriculture as a business in India depends upon quality of the seeds, fertilizers, pesticides, herbicides, their cost, and the cost of the final product. Usual environmental catastrophes such as overprecipitation or draught or attack of acclimatized pest, microbial disease or even over production of the product makes the final price of the product highly temperamental. We wanted to use synthetic biology to improve yield of the product and help farmer make some more profit out of it. We cannot engineer mother Nature to reduce redundant rainfall or increase rainfall in dry areas using synthetic biology!
Hence, we decided to go down to the roots (both literally and figuratively!) of agriculture. In this project, we focus on differentiation between crops and weeds and the assimilation of inorganic phosphorous in the soil. It has been established in a lot of scientific publications that every plant (crop in our case) maintains its own identity near its roots, the area what scientists call, the rizosphere, by secreting some unique chemicals. We propose an engineered soil microbe, Bacillus subtilis, with a circuit built inside it, which will switch on when the microbe identifies those unique chemicals (henceforth referred to as exudates). This way, B. subtilis, will achieve first goal of our project.
Further, we wish to utilize this method of identification and differentiation of plants to facilitate selective growth of crops in field. This time, we turn our attention to the fertilizers and pesticides. As mentioned earlier, there is a lot of uncertainty in the prices of vegetable products in India. This makes agriculture a mercurial business. How can one use synthetic biology to help farmer grow same number of crops in lower investment? Yes, our project has a potential solution to it.
Farmers in India use NPK fertilizers, which are composites of Nitrogen, Phosphorous and Potassium bearing synthetic compounds. We here mainly focus on Phosphorous. There is a lot of inorganic phosphorous available in the soil. But crops cannot directly assimilate it. Phosphorous that is provided to plants via NPK fertilizers is in specific soluble form. We wish to engineer the B. Subtilis to produce phytases and secrete those enzymes outside the cell. Phytases can convert inorganic phosphorous into such a form which crops can uptake.
Now where does identification and differentiation stand in this part of the project? We propose to incorporate a genetic circuit that contains an inducible promoter, which is induced by the exudates of that specific crop. By using a transcription regulator, we propose to build an amplification circuit inside the cell, which will keep on producing phytases once the promoter is induced. The exudate which corresponds to weed cannot induce the promoter in the circuit, hence phytases will not be produced in the rizosphere of weeds. There will not be conversation of inorganic phosphorous into assimilable phosphorous which will subdue the growth of weeds.
In a nutshell, our project identifies broad spectrum problems faced by farmers in India and tries to offer a small but potentially effective solution to those.