ONION IS HOST FOR TWO PHYTOPLASMA LINEAGES, SUBGROUPS 16SrI-A AND 16SrI-(B/L)L, IN LITHUANIA: A HinfI SITE REVEALED A SNP MARKING DIVERGENT BRANCHES OF EVOLUTION

R. Jomantiene, R.E. Davis, I.-M. Lee, Y. Zhao, K. Bottner-Parker, D. Valiunas, R. Petkauskaite

Abstract


Onions (Allium cepa L.) grown for seed production in the Kaunas region of Lithuania exhibited mild yellowing of leaves and stems, stunting, phyllody, and proliferation of flowers. RFLP and sequence analysis of PCR-amplified 16S rRNA, ribosomal protein (rp), and secY genes revealed the presence of phytoplasmas belonging to subgroups 16SrI-A (rpI-A) and 16SrI-L (rpIB, secYI-B). The results indicated that phytoplasma strains in subgroup16SrI-A (rpI-A) have potential to damage onions in Europe, as well as in North America, and for the first time demonstrated onion as a host for subgroup 16SrI-L. Subgroup 16SrI-L was distinguished based on a composite HinfI RFLP pattern of 16S rDNA that revealed the presence of two sequence heterogeneous rRNA operons in this subgroup, thus showing the significance of composite RFLP patterns for phytoplasma identification and classification. A single nucleotide polymorphism (SNP) in the first base of one HinfI recognition site (5’-GANTC-3’) marked the divergence of major phylogenetic branches, supporting the concept that SNPs provide powerful molecular markers of phytoplasma evolution.

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DOI: http://dx.doi.org/10.4454/jpp.v92i2.190

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