What is the primary feature of Phytoplasma organisms?

Phytoplasma organisms are indeed classified as pleomorphic mollicutes, which are a group of bacteria that lack a rigid cell wall and can change shape. They are specifically found within the phloem tissue of plants, where they interact closely with the host cell and can significantly affect plant health. This pleomorphic quality allows them to adapt to various host environments, contributing to their pathogenicity.

Phytoplasmas are not able to be cultured on artificial media, which distinguishes them from many other bacterial pathogens; they require living plant tissues for growth. Their lack of a rigid outer cell wall further confirms that they do not fit the descriptions associated with Gram-positive bacteria or those that form spores. Thus, the defining characteristic of being pleomorphic mollicutes residing in the phloem is what aligns perfectly with the nature of phytoplasma organisms.