Evolved #systems (biological and social) are always more complex than at first sight.
Chloroplasts do more than photosynthesis: They're also a key player in plant immunity
https://phys.org/news/2023-10-chloroplasts-photosynthesis-theyre-key-player.html
> Scientists have long known that chloroplasts help plants turn the sun's energy into food, but a new study, led by plant biologists at the University of California, Davis, shows that they are also essential for plant immunity to viral and bacterial pathogens.