Which types of bacteria are known to only live in live plant tissue?

Phytoplasmas and spiroplasmas are specialized types of bacteria that are obligate parasites, meaning they can only survive and reproduce inside living plant tissue. They lack the ability to exist freely in the environment like other types of bacteria. These bacteria are particularly known for causing various plant diseases by disrupting the plant's normal physiological processes.

Phytoplasmas, which are related to mycoplasmas, infect the phloem of plants and can lead to symptoms such as yellowing, stunting, or abnormal growth, ultimately affecting the plant's health and yield. Spiroplasmas share similar pathogenic behaviors and ecological niches. Their specific adaptations to plant tissue make them particularly unique, as they do not have the required cellular machinery to thrive outside of their host plant.

Other options present bacteria or fungi that have different habitats or survival strategies. While actinobacteria and mycoplasmas are important in their respective roles within the ecosystem and can survive in various environments, they do not exhibit the strict plant tissue dependence seen in phytoplasmas and spiroplasmas. Pathogenic fungi, although they can also live on plants and affect them, belong to a different classification of organisms entirely, distinct from bacteria.