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SIGNS OF PHYTOPLASMAS

Phytoplasmas are smaller than ordinary bacteria and so, like viruses, they are most easily seen using an electron microscope. However, phytoplasmas also can be seen in the phloem using light microscopy, although this requires use of fluorescent dyes. These dyes bind to DNA (the genetic material that phytoplasmas possess) and glow when exposed to UV light. Phloem cells do not contain DNA under normal circumstances.

This photo shows phytoplasma cells (see arrow) in a phloem cell. The phytoplasma cells have been stained and then exposed to UV light.