My question is if a human were to have plant DNA, such as that from a flower, injected into their bloodstream would this have a negative or positive effect on their health? Or would it not affect them at all?

In this world, they have access to a larger amount of DNA.

By negative I mean would this kill them? Or would it possibly dwindle their immune system in any way?

By positive I mean would it strengthen their immune system. Give them some sort of minerals?

Or would doing this have no effect on the person in question at all? They would just have plant DNA in them.

I hope this question isn't too vague. I don't need a big in-depth answer just someone familiar with human immune systems and stuff like that and how they work just to know if it would be a negative or positive reaction or none at all.