Abstract:

【Objective】 The objective of this study is to investigate and identify the alternative host plants of paulownia witches’-broom phytoplasma (PaWB) in natural condition. 【Method】 Using universal primers for phytoplasmal 16S rRNA gene, nested PCR was conducted to detect phytoplasmas from 16 species of plants with/without symptoms of yellowing, little leaf, winkle leaf, witches’-broom and growing around paulownia plants infected with PaWB, and then sequencing and phylogenetic analyses of the amplified fragment were made. Indirect immunofluorescence was also used to analyze partial plant samples.【Result】A specific fragment of ca. 1.2 kb in length was amplified with nested PCR from 7 species of plants, Chinese yam (Dioscorea opposita), groundcherry (Physalis angulata), pepper (Capsicum annuum), peanut (Arachis hypogaea), goosegrass (Eleusine indica), bristle grass (Setaria viridis) and musdky guard (Cucurbita moschata) along with the positive control of PaWB. The sequencing and phylogenetic results showed that all the phytoplasmas detected in the 7 species of plants and the one from diseased paulownias belonged to 16Sr I-D subgroup of aster yellows phytoplasma group. Indirect immunofluorescence analysis using antibody to PaWB Tuf protein indicated that specific fluorescence was easily detected in paulownia plants infected with Beijing and Heze isolates of PaWB, but not either in healthy paulownia plants or in CaWL, DoY, AhY, CmA phytoplasma-infected plants. 【Conclusion】 Paulownia witches’-broom phytoplasma were detected from 7 species of plants, which were probable natural hosts of PaWB.

Key words: paulownia witches’-broom, phytoplasma, 16S rRNA gene, nested PCR, indirect immunofluorescence, host plant