Caratterizzazione molecolare di ceppi di ‘Candidatus Phytoplasma asteris’ da mais

The mollicutes ‘Ca. P. asteris’ and Spiroplasma kunkelii sp. nov. are reported as agents of maize bushy stunt (MBS) and corn stunt (CS) diseases, among the most economically important maize (Zea mays L.) diseases, whose incidence has increased in the Caribbean, Central and Southern American countries. Plants showing disease symptoms such as marginal chlorosis on young leaves, stunting, reddening of leaves, early and abnormal ripening, precocious death, poor and shriveled grains in kernels, that are in some cases also malformed, were collected in distinct Colombia and Cuba regions. From both countries phytoplasmas belonging to 16SrI-B ribosomal subgroup were identified only in samples from symptomatic materials. Further molecular characterized by RFLP analysis and/or sequencing of ribosomal protein rpL22/rpS3, tuf, amp and groEL genes were carried out and allow distinguishing the aster yellows strains detected in Cuba and in Colombia in maize from all other aster yellows phytoplasmas used as reference. Additionally, using a specific restriction enzyme, in real and in silico RFLP analysis on rpL22/S3 was possible to differentiate the MBS Colombian strain, from the Cuban strain. This multilocus gene strain characterization will enable to devise the best management strategies, to contain and prevent the spreading of this epidemic disease.