XXXX of plants.

@entity9463 @entity114 @entity803 @entity15398 @entity347
Plants can be infected by two types of wall-less procaryotes, spiroplasmas and @entity9463 -like organisms (MLO), both located intracellularly in the phloem tissues of affected plants. Spiroplasmas have been cultured, characterized and shown to be true members of the class Mollicutes. MLO have not yet been cultured or characterized; they are thought to be @entity9463 -like on the basis of their ultrastructure as seen in situ, their sensitivity to @entity803 and resistance to @entity114 . Mycoplasmas can also be found on the surface of plants. These extracellularly located organisms are members of the following genera: @entity15398 . @entity9463 and Acholeplasma. The presence of such surface mycoplasmas must not be overlooked when attempts to culture MLO from affected plants are undertaken. Sensitive serological techniques such as the enzyme-linked immunosorbent assay (ELISA) can successfully be used to compare the MLO located in the phloem of affected plants with those eventually cultured from the same plants. In California and Morocco periwinkles naturally infected with both @entity15398 and MLO have been reported. With such doubly infected plants, the symptom expression has been that characteristic of the @entity347 (phyllody or stolbur), not that given by @entity15398 . Only @entity15398 can be cultured from such plants, but this does not indicate that @entity15398 is the causal agent of the disease expressed by the plant. In California many nonrutaceous plants have been found to be infected with @entity15398 . Stubborn affected citrus trees represent an important reservoir of @entity15398 , and Circulifer tenellus is an active leafhopper vector of @entity15398 . Hence, it is not surprising that in California MLO-infected fruit trees could also become infected with @entity15398 but it would not mean that @entity15398 is the causal agent of the disease. Criteria are discussed that are helpful in distinguishing between MLO infections and @entity15398 infections.
