1. Sorghum Transformation
The gene gun method of transformation is one of the main methods used to deliver DNA into plant cells.

2. Sorghum Transformation
Troy Weeks ‘explants’ immature embryos from sorghum seeds.

3. Sorghum Transformation
Immature sorghum seeds have been sterilized with bleach and alcohol to kill any bacteria, etc. This will be the source of the callus tissue.

4. Sorghum Transformation
The immature embryo is the tiny undeveloped plant within the seed. A scalpel and tweezers are used to cut each seed open and take out the embryo. This is called explanting.

5. Sorghum Transformation
The immature embryo is very small. Typically, this lab explants around in a day.

6. Sorghum Transformation
Curt Friedel tries his hand at explanting. Will he be the next genetic engineer?

7. Sorghum Transformation
Curt is still trying to explant. I guess Troy won’t be calling him up for a job any time soon.

8. Sorghum Transformation
Dann Husmann makes his attempt.

9. Sorghum Transformation
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After a few weeks on special media that does not contain growth hormones, callus cells develop. These are undifferentiated plant cells.

10. Sorghum Transformation
A lab assistant makes media that will be used in this process.

11. Sorghum Transformation
It takes a lot of media and materials to do genetic engineering.

12. Sorghum Transformation
The gene gun is contained in a sterile hood to prevent contamination of callus. Contamination will ruin the cells.

13. Sorghum Transformation
The gene gun is hooked up to a helium tank next to the hood. The helium is pumped into the gene gun to create pressure that propels the gold particles much like a BB gun.

14. Sorghum Transformation
Microscopic gold particles are coated with copies of the gene and possibly a selectable marker gene. They are suspended in ethanol.

15. Sorghum Transformation
A few drops of the gold particle solution are placed on macrocarriers. The ethanol evaporates and the gold sticks to the plastic film.

16. Sorghum Transformation
The pressure reaches 1100psi causing the rupture disk to rupture and propel the gold particles. A stopping screen stops the rupture disk from hitting the callus.

17. Sorghum Transformation
The macrocarrier is flipped over so the gold particles are facing down.

18. Sorghum Transformation
The gene gun in the hood with the many tools all around.

19. Sorghum Transformation
The macrocarrier has been placed in the top shelf and the plate of callus on the third shelf of the gene gun.

20. Sorghum Transformation
With the flip of a switch, air is vacuumed out of the chamber to eliminate wind resistance. Another switch starts a helium pump which builds up the pressure until it reaches 1100psi and the rupture disk breaks.

21. Sorghum Transformation
A pattern can be seen on the plate where the gold particles landed.

22. Sorghum Transformation
A pattern can be seen on the plate where the gold particles landed.

23. Sorghum Transformation
Dann Husmann takes a shot with the gene gun.

24. Sorghum Transformation
Dann Husmann takes a shot with the gene gun.

25. Sorghum Transformation
The callus is then placed on selection media. If a cell received the selectable marker gene (and hopefully the gene of interest) it will survive on the selection media.The white cells are the survivors.

26. Sorghum Transformation
When sorghum cells are injured they release phenolics, which causes the blackish purple coloring seen around the cells on the plate.

27. Sorghum Transformation
Troy Weeks points out some of his work to eager students.

28. Sorghum Transformation
The cells that survive selection media are placed on growth media that contains hormones that signal the cells to divide and differentiate into roots and shoots.

29. Sorghum Transformation
Once a plant develops well enough it is placed in an individual growth tube.

30. Sorghum Transformation
Genetic engineering is a numbers game. Only about 1/100 cells bombarded with the gene gun takes up the gene. Of those, only about 1/100 have the desired expression. Therefore, they perform this process on millions of cells. Troy shows the growth chamber full of cells at different stages of the process.

31. Sorghum Transformation
The process takes approximately 8-9 months from explanting tissue samples to form into callus to having a grown plant from bomarded callus. The growth chamber is full of cells or plants at each step along the way.

32. Sorghum Transformation
Blue color can also be used as a selectable marker. The blue tissue is transgenic and contains a gene that makes it blue in a certain solution.