Microscopic and molecular evidence of phytoplasma in murta plants (Ugni molinae Turcz.) affected by witches'-broom disease

Microscopic and molecular evidence of phytoplasma in murta plants (Ugni molinae Turcz.) affected by witches'-broom disease The murta or murtilla (Ugni molinae Turcz., Myrtaceae) is an evergreen shrub fruit native to Chile. Its fruit is an aromatic and tasty globose berry, great potential as a fresh product and for industrialized production. The most common and destructive disease of the foliage of this shrub is characterized by uncontrolled branching and known as "witches'-broom" disease; this could be related to a biotic agent. Histological cuts were made in tissues with and without symptoms of the disease, which were visualized by transmission electron microscopy. Pleomorphic microorganisms similar to phytoplasma in phloem tissue of diseased plants were seen. PCR molecular testing confirmed the presence of these prokaryotes in diseased tissues, but not in asymptomatic plants, suggesting that these microorganisms could be associated as causal agents of witches'-broom disease in murta. Future research is expected to identify this phytoplasma, its vectors and its dispersion in southern Chile.