Phytoplasmas have been reported to infect cassava in several countries worldwide, and to be associated with different symptoms. In America these include frog skin disease associated with X-disease phytoplasmas in Colombia and Brazil and witches’ broom disease associated with aster yellows and X-disease phytoplasmas respectively in Cuba and in Brazil. Cassava plants with frog skin symptoms were detected in Costa Rica and Paraguay and sampling was carried out in 2012 to verify phytoplasma presence and identity. Nucleic acid was extracted from symptomatic roots, leaf petiols and midribs of 202 samples corresponding to 37 plants from Costa Rica and 10 plants from Paraguay. Direct and nested PCR assays targeting the 16S rDNA gene were carried out with phytoplasma general and group specific primer pairs. In particular by using 16SrI and –III group specific primers in nested-PCR assays 16SrI and –III phytoplasmas were identified. Moreover 57 samples were processed with nested-PCR assays using general primer pairs and phytoplasmas belonging to 16Sr groups -I, -X and -XII were identified in the 64%, 14% and 22% of samples from Costa Rica, while 16SrI and –XII phytoplasmas were identified in the 75% and 25% of samples from Paraguay. Moreover, in silico and real RFLP analyses showed the presence of profiles differentiable from each others and from those of reported strains in the majority of the phytoplasma groups detected. SNPs analysis confirmed the presence of further polymorphism among and between Costa Rica and Paraguay phytoplasma strains belonging to 16SrI, -X and –XII groups. Further analyses were performed on tuf gene to avoid the presence of false negative (Bacillus spp) sometimes obtained by 16Sr DNA amplification. RFLP analyses on both 16S and tuf amplicons confirmed the presence of phytoplasmas related to different ribosomal groups.
Phytoplasma infections in cassava plants with frog skin disease from Costa Rica and Paraguay
CONTALDO, NICOLETTA;PALTRINIERI, SAMANTA;BERTACCINI, ASSUNTA;MEJIA DE LOS RIOS, JUAN FERNANDO
2014
Abstract
Phytoplasmas have been reported to infect cassava in several countries worldwide, and to be associated with different symptoms. In America these include frog skin disease associated with X-disease phytoplasmas in Colombia and Brazil and witches’ broom disease associated with aster yellows and X-disease phytoplasmas respectively in Cuba and in Brazil. Cassava plants with frog skin symptoms were detected in Costa Rica and Paraguay and sampling was carried out in 2012 to verify phytoplasma presence and identity. Nucleic acid was extracted from symptomatic roots, leaf petiols and midribs of 202 samples corresponding to 37 plants from Costa Rica and 10 plants from Paraguay. Direct and nested PCR assays targeting the 16S rDNA gene were carried out with phytoplasma general and group specific primer pairs. In particular by using 16SrI and –III group specific primers in nested-PCR assays 16SrI and –III phytoplasmas were identified. Moreover 57 samples were processed with nested-PCR assays using general primer pairs and phytoplasmas belonging to 16Sr groups -I, -X and -XII were identified in the 64%, 14% and 22% of samples from Costa Rica, while 16SrI and –XII phytoplasmas were identified in the 75% and 25% of samples from Paraguay. Moreover, in silico and real RFLP analyses showed the presence of profiles differentiable from each others and from those of reported strains in the majority of the phytoplasma groups detected. SNPs analysis confirmed the presence of further polymorphism among and between Costa Rica and Paraguay phytoplasma strains belonging to 16SrI, -X and –XII groups. Further analyses were performed on tuf gene to avoid the presence of false negative (Bacillus spp) sometimes obtained by 16Sr DNA amplification. RFLP analyses on both 16S and tuf amplicons confirmed the presence of phytoplasmas related to different ribosomal groups.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
