Do they integrate sensory information from those stimuli though? Do they create a subjective representation of what those stimuli are, and use that representation to guide their actions? I think those are the questions I would ask to find out if they could experience something as subjective as suffering. As far as I know the answer is negative for plants.

If you could describe something functionally akin to ganglia or a CNS in a plant, I would have to reconsider my position.