Team:Gaston Day School/Results


Despite not having the ability to work in the lab, we were able to find lots of information on kudzu and phaseolotoxin. Kudzu is an invasive species that came from Asia and has now consumed a lot of land in the southeastern states of the United States. There are many different methods of eradicating kudzu. These include the use of fire, mowing, chemicals, insects, goats, and fungus. These methods are all expensive, dangerous, or take many years. As a result of the difficulty to control kudzu, many plots of land go untouched because of Kudzu. In recent studies and modeling, our team discovered that in Gaston county, if kudzu was not managed it would cover over 300 hectares. For comparison, Gaston County is 94405.067 hectares. If this were to continue, we face problems as our population grows.

Pseudomonas syringae pv. Phaseolicola produces the chlorosis inducing toxin, phaseolotoxin. However, there are naturally occurring strains of these pathovars that do not produce this toxin and that does not even have the DNA that synthesizes it. Phaseolotoxin effectively inhibits the ornithine carbamoyltransferase (OTCase) activity in plants.

Pseudomonas syringae pv. Phaseolicola also produces a phaseolotoxin-resistant OCTase (ROCTase) to protect itself against its own toxin. ROCTase is a product of the arg-k gene and is only synthesized under conditions that lead to phaseolotoxin production. The argK gene is located in the chromosomal fragment in the Pht cluster, where genes involved in the production of phaseolotoxin are contained.

A quantitative microbiological assay for the phaseolotoxin was developed based on the ability of the toxin to inhibit the growth of E.coli on an arginine-deficient medium. Toxin-inhibition of these indicator strains can be shown to be OCTase to reverse growth inhibition. More specifically, phaseolotoxin is a reversible inhibitor of the enzyme ornithine carbamoyl-transferase, that catalyzes the formation of citrulline from ornithine and carbamoyl phosphate in the sixth step of the arginine biosynthetic pathway.

Moving forward with this information, we have a strong and supported hypothesis that the phaseolotoxin will target Kudzu’s fast-growing and regenerative system and reverse the growth inhibition. This process is projected to be as effective as using fire, however, it is more environmentally friendly because we can develop an off switch to protect surrounding life. After getting successful lab test results and proving that phaseolotoxin does have the ability to eliminate kudzu after experimental trials, approval from the local government and other related authorities are needed before we put it into commercial use. Additionally, the production of a large amount of our design may be another difficulty. We can try to make connections to universities nearby to find out if they will be able to improve our methods for volume production.

Kudzu Background