Summary Viral infection of marine phytoplankton releases a variety of dissolved organic matter (DOM). The impact of viral DOM (vDOM) on the uninfected co‐occurring phytoplankton remains largely unknown. Here, we conducted transcriptomic analyses to study the effects of vDOM on the cyanobacterium Prochlorococcus , which is the most abundant photosynthetic organism on Earth. Using Prochlorococcus MIT9313, we showed that its grow...