Detection of a ‘Candidatus phytoplasma trifolii’-related strain in Xerochrysum bracteatum showing a leaf yellowing disease

Leaf yellowing and stunting symptoms were observed on the annual ornamental species Xerochrysum bracteatum in the experimental fields of Indian Agricultural Research Institute, New Delhi, India, during July-August 2017. Amplicons of about 1.8 kb and 1.2 kb were detected in all the symptomatic samples using the phytoplasma-specific universal primer pairs P1/P7 and R16F2n/R2, respectively. Pair wise analysis of 16S rRNA gene sequences, virtual RFLP and phylogeny analysis revealed that the detected phytoplasma strain is related to ‘Candidatus Phytoplasma trifolii’ and it can be enclosed in the 16SrVI-D subgroup. This is the first report 16SrVI-D phytoplasmas in X. bracteatum.