First Report of an Aster Yellows Subgroup 16SrI-B Phytoplasma Infecting Chayote in Costa Rica

Abstract

An outbreak of a witches' broom disease affected approximately 20% of plants in several chayote (Sechium edule (Jacq.) Schwartz) fields in the commercial production area of the Ujarrás Valley, Cartago Province, Costa Rica during 2000 and 2001. Affected chayote plants exhibited symptoms, including basal proliferation with severe foliage reduction, aborted flowers, and deformed fruits, suggestive of phytoplasmal infection. Two other symptomatic cucurbit species growing near the chayote fields were also identified. These species were tacaco plants (S. tacaco (Pitt.) C. Jeffrey), an edible cucurbit for domestic marketing in Costa Rica, showing severe size reduction of leaves and fruits, and Rytidostylis carthaginensis (Jacq.) Kuntze, a weed in chayote and tacaco fields, exhibiting abnormal tendril proliferation. Plants were analyzed for phytoplasma infection by a nested polymerase chain reaction (PCR) assay, using the universal rRNA primer pair P1/P7 followed by R16F2n/R16R2 (2). Phytoplasmas were detected in all symptomatic samples (18 chayote, 6 tacaco, and 3 weed) tested but were undetectable in all asymptomatic samples (10 chayote, 6 tacaco, and 2 weed). Restriction fragment length polymorphism (RFLP) analysis of PCR products (16S rDNA sequences) by separate digestion with eight restriction enzymes (RsaI, HhaI, KpnI, BfaI, HaeIII, HpaII, AluI, MseI) revealed that a phytoplasma belonging to subgroup 16SrI-B in the aster yellows phytoplasma group (16SrI) was associated with chayote witches' broom (CWB). The same or very similar phytoplasmas were found in both symptomatic tacaco and R. carthaginensis plants. Phylogenetic analysis of 16SrDNA sequences also confirmed the CWB phytoplasma to be most similar to members of subgroup 16SrI-B. Similar diseases in chayote and other cucurbits have been reported in Brazil (3), Taiwan (1), and Mexico (4). The CWB phytoplasma differs from the phytoplasma (16SrIII-J subgroup) associated with chayote in Brazil. The identities of phytoplasmas associated with cucurbits in Taiwan and Mexico are unknown. The occurrence of an aster yellows group phytoplasma in chayote may pose a potential threat to continued production and exportation of this cash crop. To our knowledge, this is the first report of 16SrI-B subgroup phytoplasmas in naturally infected cucurbits in Costa Rica. References: (1) T. G. Chou et al. Plant Dis. Rep. 60:378, 1976. (2) I.-M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (3) H. G. Montano et al. Plant Dis. 84:429, 2000. (4) E. Olivas. Rev. Fitopatol. (Lima) 13:14, 1978.

Guazuma ulmifolia (Sterculiaceae), a new natural host of 16SrXV phytoplasma in Costa Rica

“…This finding contributes knowledge about the diversity of phytoplasma diseases in Costa Rica and Central America, where the phytoplasmas detected are mainly related to groups 16SrI (Aster yellows group) (Lee et al, 2000;Villalobos et al, 2002;Saborío-R. et al 2007;Moreira et al 2010), 16SrIV (Coconut lethal yellows group) (Harrison et al, 2002;Roca et al, 2006) and 16SrIX (Pigeon pea witches'-broom group) (Kenyon et al, 1998(Kenyon et al, , 1999. New diseases related to other phytoplasma groups have been also reported in the last years, such as 16SrIII in El Salvador (Parada et al, 2006) and 16SrXXXI in Costa Rica (Villalobos et al, 2009;Lee et al, 2011).…”

“…The actual RFLP analysis with the endonucleases AluI, HaeIII, HpaII, Tru1I, TaqI (Figure 2-A), HinfI and Tsp509I (data not shown) of R16F2n/R16R2 PCR products generated patterns identical among the phytoplasmas under study but different from the RFLP pattern of phytoplasma infecting Sechium edule (subgroup 16SrI-B, Villalobos et al, 2002). The RFLP results indicated that the phytoplasma associated with GWB belonged to hibiscus witches' broom group (16SrXV), represented by 'Candidatus Phytoplasma (Ca.…”

“…Petioles and leaf midribs were used for analysis in the present study. DNA extracted from Sechium edule infected with aster yellows phytoplasma (16SrI-B) (Villalobos et al, 2002) was used as a positive control.…”

Marcadores moleculares asociados con resistencia a la enfermedad punta morada en papa

“…recientemente, los esfuerzos en la investigación fueron enfocados a la caracterización molecular del germoplasma, la identificación de nuevas razas de fitoplasmas y al establecimiento de las relaciones genéticas entre colectas con el fin de hacer un uso y conservación mas adecuado e identificar marcadores moleculares asociados con la respuesta al daño causado por estos patógenos (Villalobos et al 2002, Borth et al 2002, Lee et al 1998, Laviña y Battle 2002. a pesar del desarrollo de tecnologías basadas en el DNA, que permitieron contar con un mayor número de marcadores como los rFLPs y los basados en Pcr como son RAPD, SSR, AFLP (Milbourne et al 1997) en méxico no se han realizado estudios utilizando estas técnicas, pero se debe de considerar que los marcadores RAPDs tienen como desventaja no ser reproducibles entre laboratorios (Demeke et al 1993), aunque Pecina et al (2001) demostraron la factibilidad de su reprodubilidad.…”

Abobrinha-de-moita: um novo hospedeiro de fitoplasma do grupo 16SrIII

“…afetadas pelo superbrotamento, em Taiwan (Lee et al, 1993). Na Costa Rica, um fitoplasma do grupo 16SrI foi identificado em campos comercias de chuchu e de Sechium tacaco, bem como na planta daninha Rytidostylis carthaginensis (Villalobos et al, 2002). Foi relatada ainda a ocorrência de um fitoplasma do grupo 16SrXII em plantas infectadas de Cucumis myriocarpus Naud., na Austrália (Saqib et al, 2006).…”