CHARACTERIZATION OF AN ASTER YELLOWS PHYTOPLASMA ASSOCIATED WITH CATHARANTHUS LITTLE LEAF IN ARGENTINA
L. Torres, E. Galdeano, D. Docampo, L. Conci
Periwinkle plants showing severe chlorosis and littleleaf symptoms were observed in Córdoba (Argentina). These symptoms have previously been correlated with a phytoplasma infection based on electron microscopy, serology and PCR techniques. The aim of the present work was to characterize the Argentinian catharanthus little leaf phytoplasma (ACLL) at molecular level using PCR-RFLP. Using the universal phytoplasma primers P1/P7 and R16F2/R16R2, we amplified the 1.8 kb fragment extending from the 5’-end of the 16S rRNA gene to the 5’-region of the 23S rDNA, and a 1.2 kb fragment from the 16S rRNA gene. The specific aster yellows primers P1/AYint were also used and the expected amplified fragment of 1.5 kb was obtained. The P1/P7 and R16F2/R16R2 fragments were digested with 9 and 10 restriction endonucleases respectively. The RFLP analysis revealed, for most of the enzymes assayed, identical patterns to those of members of the aster yellows group (16SrI), subgroup B, except for Rsa I and Hae III, which generated profiles similar to those presented by phytoplasmas from subgroup C. These differences could be explained by sequence heterogeneity of the two rRNA operons that are present in all phytoplasmas. Confirmation of the ACLL phytoplasma in Argentina expands southwards the already wide geographical distribution and diversity of the 16SrI-B (Aster Yellows) group.