Evidencias microscópicas y moleculares de la presencia de fitoplasmas en plantas de murta (Ugni molinae Turcz: ) afectadas por la enfermedad "escoba de bruja"

Abstract

RESUMENLa murta o murtilla (Ugni molinae Turcz., Myrtaceae), es un arbusto frutal siempre verde, nativo de Chile. Su fruto es una baya globosa muy aromática y sabrosa, de gran potencial en consumo fresco e industrializado. El arbusto presenta en el follaje una enfermedad caracterizada por una incontrolable ramificación conocida como "escoba de bruja", siendo la más común y destructiva, la cual podría estar relacionada con un agente biótico. Se realizaron cortes histológicos en tejidos con y sin síntomas de la enfermedad, los cuales se visualizaron mediante microscopía electrónica de transmisión. Se observó la presencia de microorganismos pleomórficos similares a fitoplasmas en los tejidos del floema en plantas enfermas. Pruebas moleculares mediante PCR permitieron confirmar la presencia de estos procariontes en tejidos enfermos, pero no en plantas asintomáticas, lo cual sugiere que estos microorganismos podrían estar asociados como agentes causales de la enfermedad escoba de bruja en murta. En futuros trabajos se espera obtener la identificación de este fitoplasma, sus vectores y dispersión en el sur de Chile. Palabras clave: Myrtaceae, molicutes, diagnosis, TEM, PCR. ABSTRACT Microscopic and molecular evidence of phytoplasma in murta plants (Ugni molinae Turcz.) affected by witches'-broom diseaseThe 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.

Insect Diversity, Community Composition and Damage Index on Wild and Cultivated Murtilla

“…The main characteristic of this disease is an uncontrolled branching associated with biotic factors. Moreover, this plant disease is characterized by a reduction in the size of shoots and overgrowth of these; the leaves become smaller and tighten acquiring a reddish to yellowish color, not allowing the development of fruits and when they reach some develop, have a bad taste (Andrade et al, 2009 Aguilera et al (2009) reported that this disease was found in some experimental plots cultivated with U. molinae in the Region of La Araucanía. The Margalef index for wild species was higher (12.98) than other reports for cultivated ecosystems.…”

Phytoplasma infection alters morpho-anatomical and physiological traits in Ugni molinae Turcz.

“…Phytoplasma infection usually results in dwarfism and leaf alterations (Camarena & De la Torre 2008, Andrade et al 2009). Here we found that symptomatic branches of U. molinae were smaller, thinner, and had smaller leaves (Table I).…”

“…Plants affected by the disease show increased branching, dwarfism, and color change in affected branches (Lee et al 2000, Camarena & De la Torre 2008, Andrade et al 2009. The phytoplasm infects the phloem of the plant (Andrade et al 2009, Arismendi et al 2010, 2011, altering normal vegetative development. Fruit set is decreased and fruits, when present, have bad flavor (personal observation, Andrade et al 2009).…”

“…The phytoplasm infects the phloem of the plant (Andrade et al 2009, Arismendi et al 2010, 2011, altering normal vegetative development. Fruit set is decreased and fruits, when present, have bad flavor (personal observation, Andrade et al 2009). To our knowledge, no studies have evaluated fruit quality of healthy and infected plants of Ugni molinae.…”