First Report of ‘Candidatus Phytoplasma asteris’ Affecting Woody Hosts (Fraxinus uhdei, Populus nigra, Pittosporum undulatum, and Croton spp.) in Colombia

Abstract

Phytoplasmas of the 16SrVII group in ornamental Fraxinus uhdei trees (1) growing in different cities of the Colombian Andes have been reported (2). In surveys made in Bogotá during March and May 2011, symptoms suggestive of phytoplasma infection were observed in ornamental woody species: Croton spp. (Euphorbiaceae), Pittosporum undulatum (Pittosporaceae) and Populus nigra (Salicaceae) trees, growing close to infected F. uhdei (Oleaceae). Symptoms included witches' broom, yellowing, dieback, epicormic sprouts, tufted foliage, abnormal elongation or shortening of internodes, and deliquescent branching leading to dramatic changes in crown architecture. P. undulatum and F. uhdei are introduced species representing the second and third most abundant trees in the city. P. nigra is an introduced species and Croton spp. is an Andean genus. In order to screen for the presence of phytoplasmas in Croton spp., P. undulatum, and P. nigra, four individuals of each species and two F. uhdei trees were sampled. For DNA extraction, 1 g of vascular tissue from young stems was used. Samples were tested by nested PCR with primers P1A/P7A (4) followed by R16F2n/R16R2 (3). The frequency of phytoplasma detection varied among species; P. undulatum and Croton spp. had three positives each, while P. nigra had one positive. Both F. uhdei were positive. Sequences from the amplicons (three reads) were aligned. BLAST analysis of 16S rDNA sequences from the four species tested had 99.2 to 99.7% similarity to 16SrI group sequences. Phylogenetic analysis further confirmed this relationship. Virtual sequence analysis using the iPhyclassifier tool ( http://plantpathology.ba.ars.usda.gov/cgi-bin/resource/iphyclassifier.cgi ) showed that the sequence derived from P. undulatum (JQ730861) produced an identical RFLP pattern to group 16SrI-B (reference sequence NC_005303). RFLP similarity coefficients of the phytoplasmas from F. uhdei, Croton spp., and P. nigra (JQ730859, JQ730859 and JQ730861) were less than 0.97, suggesting the presence of a new subgroup within group 16SrI. The vectors of phytoplasmas are unknown in the region. Phytoplasma hosts previously reported in Colombia are: Solanum quitoense (16SrIII), Manihot esculenta (16SrIII), Liquidambar styraciflua (16SrI and 16SrVII), Elaeis guineensis (16SrI and 16SrIII), Coffea arabica (16SrIII), Cordia alliodora (16SrIII), Solanum tuberosum (16SrV and 16SrXII), and Zea mays (16SrI). To our knowledge, this is the first report of Croton spp. and P. undulatum as phytoplasma hosts. Phytoplasmas of group 16SrI are known to infect more than 100 species of different families worldwide. Detection of this group in several tree species and the observation of similar symptoms in other trees species raises concerns about a possible epidemic affecting plants in the Andean region. Implications are at several levels: i) epidemiological, with infected trees representing a potential inoculum source for other ornamental plants or crops growing in the agricultural surrounding areas; ii) economic, since eventually it will be necessary to replace diseased plants; and iii) environmental, because of the negative impact on the services provided by trees and green areas. References: (1) J. J. Filgueira et al. Plant Pathology 53:520, 2004. (2) L. Franco-Lara et al. Fitopatología Colombiana 29:32, 2005. (3) D. E Gundersen et al. Phytopathol. Mediterr. 35:144, 1996. (4) I-M. Lee et al. Int. J. Syst. Evol. Microbiol. 54:1037, 2004.

Especies Arbóreas de las Familias Euphorbiaceae, Pittosporaceae y Salicaceae son Infectadas por ‘CA. Phytoplasma fraxini’ y ‘CA. Phytoplasma asteris’ en Infecciones Mixtas en Bogotá, Colombia

“…Phytoplasma fraxini' subgrupo 16SrVII-A en Bogotá, infectando árboles de Croton spp., P. nigra y P. undulatum obtenida por PCR anidada (Figura 3 A), secuenciación (Tablas 2 y 3, Figura 4) y RFLP (Figuras 3B y 3C) en los mismos árboles en los cuales en un trabajo anterior se demostró la presencia de fitoplasmas del grupo 16SrI (Perilla et al, 2012, Franco-Lara, 2013. Los resultados presentados en este trabajo indican que frecuentemente los fitoplasmas del grupo 16SrVII se encuentran en infecciones mixtas con fitoplasmas del grupo 16SrI en los árboles evaluados.…”

Plant–Pathogen Interaction-Related MicroRNAs and Their Targets Provide Indicators of Phytoplasma Infection in Paulownia tomentosa × Paulownia fortunei

“…They live in the phloem tissue of plants and are transmitted by insect vectors [ 1 ]. It has been reported that phytoplasmas are the pathogens associated with a large number of diseases in several hundred economically important plants [ 2 , 3 ], and Paulownia plants are no exception [ 4 , 5 ]. Paulownia witches’ broom (PaWB) disease, caused by the phytoplasma in the subgroup 16SrI-D of aster yellows [ 1 , 6 ], has resulted in extensive losses in the yields of paulownia timber, leading to significant economic losses.…”

Leafhoppers Exitianus atratus and Amplicephalus funzaensis transmit phytoplasmas of groups 16SrI and 16SrVII in Colombia

“…In Colombia, as in other parts of the world, phytoplasma diseases are recognized due to their increasing impact on crops and ornamental plants, either because they are new diseases, known diseases with uncertain aetiology or diseases with new geographical distributions (Bertaccini & Duduk, ). In the last 15 years, several new phytoplasma diseases in urban trees have been described in Bogotá (Griffiths et al ., ; Franco‐Lara & Filgueira, ; Perilla‐Henao et al ., ; Perilla‐Henao & Franco‐Lara, ; Franco‐Lara & Perilla Henao, ), but until now there was no information about the insect vectors present in this area.…”

“…Phytoplasmas of groups 16SrI (‘ Ca . Phytoplasma asteris’) and 16SrVII are the predominant strains detected in the trees of Bogotá (Perilla‐Henao et al ., ; Perilla‐Henao & Franco‐Lara, ), although groups 16SrV, 16SrIX and 16SrXII have also been detected in L. styraciflua (authors’ unpublished data). The incidence of this disease varies among tree species, but it ranges between 36% in Croton spp.…”

“…The presence of phytoplasmas has been confirmed in Bogotá in introduced and native species, such as Liquidambar styraciflua (authors’ unpublished data), Pittosporum undulatum , Populus nigra and Croton spp. (Perilla‐Henao et al ., ; Perilla‐Henao & Franco‐Lara, ) and, more recently, in Acacia melanoxylon , Eugenia sp., Magnolia grandiflora and Quercus humboldtii (Franco‐Lara & Perilla Henao, ). The tree populations of the above‐mentioned species display symptoms such as yellowing, epicormic shoots, witches’ brooms, tufted foliage, and abnormal elongation of the tips of branches, which produce a deviation from the normal morphology of the trees.…”