Can I realize displaying action potential of a plant in a very minimal setup?
The answer is that yes, you can probably use the TI instrumentation amplifier, but it's not as simple as you may think. It will be a project. You can find the schematic for the SpikerBox on the Backyard Brains web site, and it does use an instrumentation amplifier, an AD623. But there's a lot more to it than that. How comfortable are you with building analog electronic circuits?

At the end of the day the SpikerBox is just an amplifier. It takes a faint biological signal and makes it audible. If your objective is to display the signals from the plant on an oscilloscope, you may not need an amplifier, because your oscilloscope already comes with one. Have you tried just hooking just hooking the oscilloscope probes up to the plant directly? If the signal is in the range of a several mV you should be able to see something.