Everything kills everything else. Living things are merely temporary storage for genetic information. The genetic information that increase's its number of redundant backups faster then the number of instance failures wins.
However, if you're of the opinion that is unethical to cause more suffering and that killing other beings just to ensure your own survival then plants having sentience is a pickle.
Something has to give. You have to give in to the circle of life and acknowledge that your survival will bring in some measure of suffering to other beings. Or sacrifice yourself since there is no way to eat ethically by your standards.
Obviously, the vast majority of people will choose survival. But now they have to draw a line. What's friend and what's food? And once you draw that line, you have to defend that choice. You can't just say "because it's X", you have to explain why it is so.
I mean, learning all of this has just made me more of a "speciesist". I don't believe there is any way to resolve the conflict.
These are hard questions, I don't expect anyone to have the answers.