engleski

Phytoplasma ribosomal subgroup 16SrIX-C – A newly described phytoplasma species in Croatia

Phytoplasmas (genus ‘Candidatus Phytoplasma’) are wall-less, uncultivable and insect-transmitted bacteria within the class Mollicutes. Within the genus, so far there are more than 40 distinct clades based on their 16S rRNA gene sequence phylogeny. The pigeon pea witches’-broom group (16SrIX ribosomal group) consists of diverse phytoplasma strains causing diseases in leguminous and herbaceous plants, vegetable crops, a nut crop (almond), herbs and weeds and, recently, a forest tree (juniper) and a fruit crop (blueberry). It is spread worldwide and found in various geographical regions including North and South America, Europe, Asia and the Middle East. In July 2019, chicory (Chicorium endivia L.) plant showing phyllody symptoms, often associated with phytoplasmoses, was sampled in vineyard surroundings of Vižinada (Istria county), Croatia. Later in the season (September 2019) in Koprivničko-križevačka county root samples from maize plants (Zea mays L.) with reddening symptoms were collected. Total nucleic acids were extracted from all samples using CTAB procedure, followed by detection and identification of phytoplasma by PCR/RFLP analyses of 16S rDNA. Subsequently, amplified 16S rDNA fragments were cloned and sequenced. Futhermore, detailed molecular characterization was performed by amplification, sequencing and phylogenetic analysis were of rp and secY genes. Phylogenetic analysis of 16S rDNA showed distinct sequences clustering of phytoplasma strains from chicory and maize, within 16SrIX-C subgroup. Moreover, phylogenetic analysis of rp and secY confirmed the affiliation to the ribosomal group IX. This a newly described phytoplasma infecting chicory and maize, as well as the first report of group IX phytoplasma in Croatia. This finding of closely related 16SrIX-C strains in geographically distant regions from different plant host species prompts further studies in elucidation the epidemiology and identification of potential insect-vectors.

‘Candidatus Phytoplasma’ ; phytoplasma ; 16SrIX-C ; phyllody ; Chicorium endivia L. ; Zea mays L.

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