Browsing by Autor "Y. Arocha"

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‘Brotes grandes’ (big bud) of potato: a new disease associated with a 16SrI‐B subgroup phytoplasma in Bolivia
(Wiley, 2005) P. Jones; Y. Arocha; O. Antesana; E. Montellano; P. Franco
Potatoes are the main crop of smallholder farmers in the Valles Cruceños, Santa Cruz Province, Bolivia. During surveys carried out from 2000 to 2003, a disease locally known as ‘brotes grandes’ (BG, ‘big bud’), was prevalent on crops in the valleys of Chilon, Saipina, Pulquina and Comarapa, where up to 90% of plants were affected in some fields. Symptoms included tuber-like growths in leaf axils, varying in size and colour from red to purple or black and bearing terminal, adventitious leaves. Tubers often produced hair-like shoots, reducing their quality and yield. Previously, this syndrome was presumed to be rhizoctoniosis, caused by basal stem infection by Rhizoctonia solani (teleomorph, Thanatephorus cucumeris). However, R. solani was absent from all diseased plants examined in the present study. As other potato diseases similar to BG have been attributed to phytoplasmas in Australia (Harding & Teakle, 1993), Poland (Hamilton, 2000), Canada (Khadhair et al., 2003) and Mexico (Martínez-Soriano et al., 1999), tissues from Bolivian plants were indexed by nested PCR (nPCR) using phytoplasma universal rRNA primer pairs P1/P7 and R16F2n/R16R2. nPCR products resulting from 43/50 BG samples and digested separately with HaeIII, RsaI or AluI endonuclease all produced identical RFLP profiles. RFLP profiles of nPCR products amplified from three samples of the mora-mora vine (Serjania perulacea) with little-leaf symptoms in hedgerows surrounding potato fields in La Tranca, Santa Cruz Province, were indistinguishable from BG profiles. 16S rDNA sequences derived from PCR products shared 99% sequence homology among BG phytoplasmas. Sequences from the phytoplasmas obtained from potato (accession no. AY725209) and from S. perulacea (accession no. AY725210) were each very similar (98%) to that of ash witches’ broom phytoplasma (accession no. AY568302). This is the first report of a phytoplasma of the aster yellows (16SrI) group associated with a potato disease in Bolivia. Work in the UK was done under Defra plant health licence no. PHL 174B/4612(09/20003).
‘Candidatus Phytoplasma lycopersici’, a phytoplasma associated with ‘hoja de perejil’ disease in Bolivia
(Microbiology Society, 2007) Y. Arocha; O. Antesana; E. Montellano; Pablo Franco; G. Plata; P. Jones
New diseases known locally as 'hoja de perejil' of tomato (Lycopersicon esculentum Mill) and 'brotes grandes' of potato (Solanum tuberosum L.) were first recognized in surveys of production fields in Bolivia during 2000-2003. Alfalfa (Medicago sativa) witches' broom and little leaf diseases of native weeds Morrenia variegata and mora-mora (Serjania perulacea) were also identified near to production fields. Phytoplasma aetiology was attributed to each of these diseases following detection and initial identification of aster yellows group (16SrI) phytoplasmas in all five diseased plant species. While potato, alfalfa and mora-mora plants contained indistinguishable 16SrI-B strains, 'hoja de perejil' (THP) and morrenia little leaf (MVLL)-associated phytoplasma strains shared 97.5 % 16S rRNA gene sequence similarity with 'Candidatus Phytoplasma asteris' and related strains and <95 % similarity with all other 'Candidatus Phytoplasma' species. Phylogenetic analysis of 16S rRNA gene sequences indicated that the THP and MVLL phytoplasmas represent a novel lineage within the aster yellows (16SrI) group and, on the basis of unique 16S rRNA gene sequences, we propose that THP and MVLL phytoplasmas represent 'Candidatus Phytoplasma lycopersici', with THP as the reference strain.
First report of a ‘ Candidatus Phytoplasma asteris’ isolate associated with a witches’ broom disease of alfalfa in Bolivia
(Wiley, 2005) Peter Jones; Y. Arocha; G. Plata
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 ≈1250 bp, and identical RFLP profiles following digestion with the restriction endonucleases HaeIII, RsaI and AluI were produced for all samples. PCR products were purified and directly sequenced, and the sequence deposited in GenBank (accession no. AY 725211). The sequence was compared with those of other phytoplasmas in GenBank using the blast protocol, 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 (‘Candidatus Phytoplasma asteris’) (Firrao et al., 2004). Alfalfa witches’ broom diseases caused by phytoplasmas have been reported from Canada (‘Ca. Phytoplasma trifolii’, Khadhair & 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 ‘Ca. Phytoplasma asteris’ infecting alfalfa. This work was supported by the Department for International Development (UK) through the Global Plant Clinic. Work in the UK was done under Defra plant health licence no. 174B/4612(09/2003). Y. Arocha thanks the Royal Society (UK) for financial support.
First report of a 16SrIII phytoplasma (X‐disease group) affecting bell pepper, strawberry (frutilla), Schinus molle and Arracacia xanthorrhiza in Cochabamba, Bolivia
(Wiley, 2010) Y. Arocha; G. Plata; Javier Franco; Gladys Main; Silene Veramendi; F. Lazcano; José L. Crespo; V. Lino; Claudene Menezes Atayde Calderon; Rodolfo Plana Llerena
Bell pepper (Capsicum annuum) and strawberry (Fragaria chiloensis, ‘frutilla’ in Spanish) are crops grown for local consumption in plots at the PROINPA Foundation, Cochabamba. Schinus molle (family Anacardiaceae, known locally as ‘molle’) is an ornamental tree widely distributed in Cochabamba urban areas, including PROINPA surroundings. Recently, symptoms of leaf size reduction and yellowing, proliferation, and shortening of internodes were observed in S. molle trees. Strawberry plants displayed rosette formation and small fruits, while bell pepper showed leaf size reduction and shortening of internodes. Symptoms were present in about 30% of strawberry and bell pepper plots, and more than 50% of the S. molle trees surrounding PROINPA exhibited symptoms. Arracacia xanthorrhiza, a nearby-grown vegetable in the celery family (Apiaceae), displayed leaf yellowing and little leaf. Symptom-bearing plants of bell pepper (4), S. molle (5), strawberry (4) and A. xanthorrhiza (4) were collected, as well as one symptomless plant of each plant species. Total DNA from leaf midribs was extracted and indexed by a nested PCR with universal 16S rRNA primers R16mF2/R1 and fU5/rU3. PCR amplicons (approximately 880 bp) were produced for almost all symptom-bearing plants, except for one plant of strawberry and one plant of A. xanthorrhiza. Symptomless plants did not yield amplicons. PCR amplicons were purified (Wizard, Promega), cloned (pGEMT-Easy Vector, Promega) and sequenced (http://www.dnaseq.co.uk). The 16S rRNA sequences of phytoplasmas detected in bell pepper (GenBank Accession No. FJ207456), strawberry (FJ207455), S. molle (FJ207454) and A. xanthorrhiza (FJ207451) showed the highest identity of 99% with the members of phytoplasma group 16SrIII (X-disease). A 16SrIII phytoplasma has been previously reported in Bolivia affecting chinaberry (Melia azadarach) trees (Harrison et al., 2003), but this is the first report of phytoplasmas belonging to group 16SrIII in bell pepper, strawberry, S. molle, and A. xanthorrhiza in Cochabamba, Bolivia. Work in the UK was done under Defra licence No. PHF 174D/5185 (08/2005). Rothamsted Research receives grants from BBSRC, UK.
First report of an isolate of ‘ Candidatus Phytoplasma australiense’ associated with a yellow leaf roll disease of peach ( Prunus persicae ) in Bolivia
(Wiley, 2005) P. Jones; Y. Arocha; O. Antesana; E. Montilliano; P. Franco
Phytoplasmas, prokaryote plant pathogens, have been reported to cause peach yellow leaf roll (PYLR) (Smart et al., 1996) and peach red leaf (PRL) diseases. The PYLR phytoplasma belongs to the 16SrX Apple proliferation group (‘Candidatus Phytoplasma mali’) (Seemüller & Schneider, 2004), but PRL still has not been assigned to a subspecific lineage in ‘Candidatus Phytoplasma asteris’ (Lee et al., 2004). Symptoms similar to PYLR disease were observed in a peach plantation at San Isidro, Santa Cruz Province, Bolivia during a survey in 2003. Older leaves had symptoms of yellowing of the leaf margin and rolling, drying and necrosis. Young leaves were tightly rolled and yellow, and proliferation of shoots was evident along branches. Many trees were dead or dying. Samples of young shoots and leaves were taken from affected and apparently healthy trees and returned to Rothamsted Research, Harpenden, UK. Total DNA was extracted and indexed by nested PCR with generic phytoplasma rDNA primers P1/P7 and R16F2n/R16R2. PCR products were characterized by RFLP analysis using the restriction endonucleases HaeIII, RsaI and AluI and direct sequencing. All samples from affected trees gave a 1250 bp PCR product and identical RFLP profiles. Sequence of phytoplasma rDNA (accession no. AY 725212) was compared with others in the GenBank database using blast. The greatest similarity (98%) was with papaya dieback phytoplasma (accession no. Y10095) from Australia, a member of the 16SrXII Stolbur group (‘Candidatus Phytoplasma australiense’) (Firrao et al., 2004). This is the first report of a peach yellow leaf roll-like disease in Bolivia, and the first record of the presence of a Stolbur group phytoplasma in peach. These results contribute to the known diversity of phytoplasmas found in peach and in Bolivian crops. This work was supported by the Department for International Development (UK) through the Global Plant Clinic. Work in the UK was done under Defra plant health licence no. 174B/4612(09/2003). Y. Arocha thanks the Royal Society (UK) for financial support.
‘Hoja de perejil’ (parsley leaf) of tomato and morrenia little leaf, two new diseases associated with a phytoplasma in Bolivia
(Wiley, 2005) P. Jones; Y. Arocha; O. Antesana; E. Montellano; P. Franco
Tomatoes (Lycopersicon esculentum), an important cash crop for smallholder farmers in the hillside production systems of the Valles Cruceños, Santa Cruz Province and Rio Chico, Sucre Province, Bolivia, were surveyed during 2002–3. Symptoms of ‘hoja de perejil’ start with adventitious sprouting of axillary buds and rapid elongation of side shoots, which break through the crown of normal leaves. Leaves of the side shoots are small and fern-like and, as the season progresses, large bushy plants are produced. Flowers are reduced in size and do not appear to set fruit, but some fruit may be produced on the early normal growth. Affected plants were screened for virus using lateral flow kits (Pocket Diagnostics®), ELISA and electron microscopy. Only Tomato mosaic virus was identified but this was not consistently associated with ‘hoja de perejil’. DNA was extracted from affected plants and tested by nested PCR for phytoplasma using generic rDNA primers P1 (Deng & Hiruki, 1991)/P7 (Schneider et al., 1995) and R16F2n/R16R2 (Gundersen & Lee, 1996). Phytoplasma products were confirmed using the endonucleases HaeIII, RsaI and AluI, and by direct sequencing of the 16S/23S spacer region (SR) with P4 (Smart et al., 1996)/P7 primers. During the tomato crop surveys, plants of Morrenia variegata (Asclepiadaceae), a vine growing in hedgerows, were found around affected tomato fields near San Rafael, Santa Cruz Province, that showed symptoms of little leaf. DNA was extracted from these plants and indexed for phytoplasma as above. Amplimers (1250 bp) with identical RFLP profiles were consistently obtained from ‘hoja de perejil’ and M. variegata with little leaf. SR sequences from ‘hoja de perejil’ (GenBank accession no. AY725208) and morrenia little leaf (accession no. AY725207) were compared with those of other phytoplasmas in GenBank using BLAST. They showed a maximum (91%) homology with phytoplasmas from the 16SrI Aster yellows group. This is the first report of ‘hoja de perejil’ disease of tomato, where infection rates of over 60% were seen in some fields of the most popular cultivar Rio Grande. This is also the first report of morrenia little leaf disease and its association with a phytoplasma. The BLAST results suggest that the phytoplasma found associated with these diseases may belong to a new 16Sr phytoplasma group. Work in the UK was carried out under Defra plant health licence no. PHL 174B/4612 (09/2003).
Occurrence of ‘ Candidatus Phytoplasma aurantifolia’ (16SrII group) in Bolivia
(Wiley, 2010) Y. Arocha; G. Plata; Javier Franco; Gladys Main; Silene Veramendi; F. Lazcano; José L. Crespo; V. Lino; Claudia Vargas Calderón; R. E. Espino Llerena
During a survey for phytoplasma at the PROINPA Foundation, Cochabamba, Bolivia in June 2008, plants of podocarpus (Podocarpus macrophyllus) showed symptoms of shortened internodes, leaf size reduction and proliferation compared to healthy ones, while those of rose (Rosa sp.) exhibited little leaf and yellowing. Both podocarpus and rose are widely distributed ornamental plants in the urban area of Cochabamba, and symptoms were observed in at least 20% of plants of each species surveyed at PROINPA. In addition, symptoms of leaf deformation, crinkling, and curling were displayed by wild plants of tomatillo (Physalis ixocarpa) growing nearby. Three plants with symptoms and one symptomless plant respectively of each species were collected. A nested PCR with universal 16S rRNA gene primers R16mF2/R1 and fU5/rU3 was carried out from total DNAs extracted from collected plant material. All plants with symptoms yielded PCR amplicons (∼880 bp), whilst the symptomless plants did not. PCR products were purified (Wizard, Promega), cloned (pGEM T-Easy Vector, Promega) and sequenced (http: http://www.dnaseq.co.uk). A representative sequence was deposited in GenBank for podocarpus (FJ207457), rose (FJ207453) and tomatillo (FJ207452). BLAST comparisons indicated that the 16S rDNA sequences of these phytoplasmas showed the highest identity (99%) with those of phytoplasma members of group 16SrII, ‘Candidatus Phytoplasma aurantifolia’. A disease in tomatillo was recently associated with a ‘Ca. Phytoplasma asteris’-related strain in Mexico (Santos-Cervantes et al., 2007). However, no phytoplasmas have been reported associated with diseases in podocarpus or rose in the region. This is the first report of phytoplasmas of group 16SrII in Bolivia and its association with diseases in podocarpus, tomatillo and rose plants. Work in the UK was done under Defra licence No. PHF 174D/5185(08/2005). Rothamsted Research receives grants from BBSRC, UK.