Abstract:

In December 2017，the W. Murcott tangerine trees，which were newly introduced in Honghe，Yunnan，showed typical HLB symptoms，i.e. blotchy mottle and“red nose”. Leaves and fruit samples of W. Murcott were collected for DNA extraction from midrib and tangerine pith for PCR detection，and sequencing by targeting the 16S rRNA gene and β-operator gene of “Candidatus Liberibacter spp.”. The results showed that samples collected from W. Murcott could be amplified the specific bands of “Candidatus Liberibacter asiaticus”（CLas）. The phylogenetic analysis based on the 16S rRNA gene and β-operator gene revealed the citrus Huanglongbing pathogen of W. Murcott belonged to CLas. In order to further analyze the genetic diversity of CLas，specific primers of three types of prophage were used to amplify DNA samples collected from W. Murcott. The result indicated the high genetic diversity of CLas samples from W. Murcott in Yunnan.

Key words: citrus, Candidatus Liberibacter asiaticus, 16S rRNA gene；prophage