J.J. Filgueira1*, L. Franco-Lara1, J.E. Salcedo1, S.L. Gaitan1 and E.R. Boa2
1 Universidad Militar Nueva Granada, Facultad de Ciencias (Biología) Cra. 11 No 101-80 Bogotá, Colombia
2 CABI Bioscience, Egham, Surrey TW20 9TY, UK
Accepted: 23 Feb 2004
The Urapan tree was introduced into Colombia around 50 years ago and has been planted along the streets of cities and rural areas throughout the Andean zone. Previously referred to as Fraxinus chinensis, recent taxonomic studies indicate that its correct name is F. udhei; a native species of Mexico (E. Wollander, personal comunication). Symptoms of Urapan dieback include yellowing of leaves, little leaves and unusual patterns of regrowth of crowns and less commonly on trunks of mature trees, which often give the foliage a tufted appearance. These symptoms are similar to those of ash yellows, a phytoplasma disease found in North America and especially the northeastern USA (Sinclair & Griffiths, 1996). Urapan trees with similar dieback symptoms have been observed in Bogotá, MedellÃn, Pereira, Manizales in Colombia and in Quito, Ecuador. Using both DAPI staining and PCR, phytoplasma infection was detected in Urapan trees affected with dieback, with samples from these trees consistently yielding amplified phytoplasma DNA by PCR using the universal 16S rDNA primers P1/Tint and R16/R2 (Smart et al., 1996; Lee et al., 1993). A phytoplasma specific product of 1200 base pairs (obtained using primer pair R16/R2) was sequenced and shown to share 94% homology with Ash Yellows (AshY3) gene 16sRNA (GenBank accession number AF105315).
There is very little information on diseases of F. udhei but there is no indication of any other causes of the symptoms characteristic of ash yellows. In a May 2000 a survey of 50 trees from seven localities in Bogotá, 48% had moderate symptoms, 52% were severely affected by the disease. This is the first confirmed record of Ash yellows occuring outside North America and has considerable significance for Fraxinus species which are widely planted in urban and rural settings throughout the Andean range as well as natural stands of F.udhei in Mexico.
Lee IM, Hammond RW, Davis RE, Gundersen DE, 1993. Universal amplification and analysis of pathogen 16S rDNA for classification and identification of mycoplasmalike organisms. Phytopathology 83, 834-842.
Sinclair WA, Griffiths HM, 1996. Ash yellows and Lilac witches'-broom: phytoplasma disease of concern for forestry and horticulture. Plant Disease 80, 468-475.
Smart CD, Schneider B, Blomquist CL, Guerra LJ, Harrison NA, Ahrens U, Lorenz KH, Seemüller E, Kirkpatrick BC, 1996. Phytoplasma-specific PCR primers based on sequences of the 16S-23SrRNA spacer region. Applied and Environmental Microbiology 62, 2988-2993.
©2004 The Authors