Abstract:

Aphids harbor not only primary endosymbionts, namely Buchnera aphidicola, but also different secondary symbionts. A single comigrating DNA band of about 1.5 kb was amplified from a population of the green peach aphid, Myzus persicae (Sulzer) collected from the experimental fields in China Agricultural University (Beijing) using a pair of “universal" primers designed based on the full 16S rDNA of a wide range of eubacteria. This target DNA was then ligated to T-vector and cloned into E. coli DH5α. The clones were analyzed using restriction fragment length polymorphism (RFLP). The results showed that EcoRⅠcut the insert into two sub-fragments (～650 bp and ～850 bp) in all assayed samples, while double digestion with EcoRⅠ and HindⅢ resulted in two different groups of RE (restriction enzyme) bands, with GroupⅠhaving only one EcoRⅠ site but Group Ⅱ having one EcoRⅠ site and one HindⅢ site. Meanwhile, GroupⅠis dominant. Based on RE grouping, the full 16S rDNA representative sequences from different groups were sequenced, and the phylogenetic analysis demonstrated that GroupⅠ belonged to Pantoea, closely related to P. agglomerans (homology: 99.70%), whereas GroupⅡwas closely related to Buchnera aphidicola, the obligate symbiont of aphids (homology: 99.50%). This is the first report that Pantoea exists in aphids.

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Key words: Myzus persicae, symbionts, Buchnera aphidicola, Pantoea, molecular identification, 16S rDNA