The Role of Grass in the Epidemiology of a Phytoplasma Disease Affecting Trees and Other Plants of the Sabana de Bogotá, Colombia

TL;DR

Grass species Cenchrus clandestinus plays a key role in spreading a plant disease caused by phytoplasmas in the Sabana de Bogotá, complicating disease management.

Contribution

Identifies Cenchrus clandestinus as a critical host for two phytoplasma species and insect vectors in the disease's spread.

Findings

Both phytoplasmas infect symptomatic trees and asymptomatic grass and weeds.

Cenchrus clandestinus hosts both phytoplasmas and insect vectors, making it central to disease epidemiology.

Closely related phytoplasma strains infect multiple plant families and insect species in the region.

Abstract

‘Candidatus Phytoplasma asteris’ and ‘Candidatus Phytoplasma fraxini’ infect at least nine species of trees, potato, and strawberry crops in the Sabana de Bogotá. We analyzed the epidemiological implications of the presence of these phytoplasma species in trees, grass, and weeds in the Sabana de Bogotá, as well as in Cicadellidae insects. Both phytoplasmas were detected in symptomatic trees of Salix humboldtiana and Sambucus nigra, and in asymptomatic grass Cenchrus clandestinus and 13 weed species. ‘Ca. P. asteris’ and ‘Ca. P. fraxini’ sequences of the 16S rRNA gene obtained from positive samples were compared with sequences from plants and insects of the Sabana de Bogotá. In each case, the sequence identity of this gene suggested that closely related strains of each species circulate in the environment, infecting plants of many families and several Cicadellidae species. Ce. clandestinus plays a key role in the epidemiology of the disease since it is a host of both phytoplasmas, of two known insect vectors, and of other Cicadellidae. Ce. clandestinus is extensively distributed in urban and rural areas. Since management efforts are hampered by the practical impossibility to remove Ce. clandestinus from the ecosystem, different strategies are needed to manage this disease.

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