Molecular detection and identification of lucerne witches broom disease in Xinjiang

In order to determine the pathogen species of lucerne witches broom disease in Xinjiang, 193 lucerne samples with witches broom disease symptom were detected by nested-PCR with R16mF2/R16mR1 and R16F2/R16R2 universal primers for phytoplasma, and 23 samples had positive results with 1.2 kb specific fragment, which had detection rate of 16.8% and confirmed that the disease was witches broom. The phylogenetic tree showed that this phytoplasma strain was one member of 16SrⅤ-B subgroup which had 99.1% homology with euonymus whitening phytoplasma in Elm Yellows Group. To the best of authors knowledge, this was the first study to determine phytoplasma pathogen of lucerne witches broom disease in Xinjiang and identify taxonomic status using molecular biological techniques. These results provide theoretical basis for early diagnosis and detection of lucerne witches broom disease.