First report of a 'Candidatus phytoplasma asteris' isolate associated with a witches' broom disease of alfalfa in Bolivia

During a survey in 2003, alfalfa (Medicago sativa) plants showing typical phytoplasma witches' broom and little leaf symptoms, were collected from fields in Limon Pampa, Rio Chico, Bolivia. Samples were evaluated by nested PCR using 16S rDNA primers P1/P7 and R16F2n/R16R2. PCR products of c.1250bp and identical RFLP profiles following digestion with the restriction endonucleases HaeIII, RsaI and AluI, were produced for all samples. PCR products were purified, directly sequenced and the sequence deposited in GenBank (Accession No. AY 725211). The sequence was compared using the BLAST protocol with those of other phytoplasmas in GenBank and had the highest similarity (98%) with the phytoplasma from ash witches' broom disease (GenBank Accession No. AY568302); a member of the 16SrI aster yellows group ('Ca. Phytoplasma asteris') (Firrao et al., 2004). Alfalfa witches' broom diseases caused by phytoplasmas have been reported from Canada ('Ca. Phytoplasma trifolii', Khadair & Hiruki, 1995; Firrao et al., 2004), Italy ('Ca. Phytoplasma phoenecium', Marcone et al., 1997; Firrao et al., 2004) and Oman ('Ca. Phytoplasma aurantifolia', Khan et al., 2001; Firrao et al., 2004). This is the first record of alfalfa witches' broom disease in Bolivia and the first report of an isolate of 'Candidatus Phytoplasma asteris' infecting alfalfa.