Detection and molecular characterization of phytoplasmas infecting apple trees in Poland

Abstract

During 2010&ndash;2012, samples from 225 apple trees growing in six regions of Poland were tested for phytoplasmas. 16S&nbsp;rRNA gene and 16S-23S spacer region sequences were amplified from total DNAs prepared from phloem tissue of apple shoots. According to the results of PCR-RFLP and sequence analyses, apple trees were infected by Candidatus Phytoplasma mali and Ca. P. asteris. Fragments of 16S rDNA plus 16S-23S spacer region of the Ca. P. mali isolates digested with HpaII enzyme showed two restriction profiles: P-I and P-II. Multiple alignments of 16S rRNA gene fragments revealed that the isolates of Ca. P. mali shared 100% sequence identity among themselves as well as with reference strains AT and AP-15 of apple proliferation phytoplasma. The nucleotide sequence of the same region of <br /> Ca. P. asteris isolates confirmed the phylogenetic relationship with reference strains OAY (MIAY) and AY1 of aster yellows phytoplasma PCR-RFLP analysis of ribosomal protein (rpl22 and rpS3), secY, and tuf genes did not show the sequence diversity of the isolates of aster yellows phytoplasma. &nbsp; &nbsp;