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Title: NEW WITCHES'-BROOM DISEASES IN NORTHERN CHINA AND THEIR ASSOCIATION WITH DIVERSE PHYTOPLASMAS

Author
item Zhao, Yan
item SUN, Q - TAIAN CHINA
item Davis, Robert
item LIU, Q - TAIAN CHINA

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/2005
Publication Date: 6/1/2005
Citation: Zhao, Y., Sun, Q., Davis, R.E., Liu, Q. 2005. New witches'-broom diseases in northern China and their association with diverse phytoplasmas. Phytopathology. 95:S117-118.

Interpretive Summary:

Technical Abstract: Phytoplasmas are cell wall-less phloem-inhabiting bacteria that cause numerous plant diseases. Being transmitted by insect vectors and having a long incubation period, phytoplasma diseases exert significant impact on agriculture and natural ecosystems. Over the summers of 2003 and 2004, pronounced witches’-broom symptoms indicative of phytoplasma diseases were observed in plants of paper mulberry (Broussonetia papyrifera), Chinese wingnut (Pterocarya stenoptera), salt-cedar (Tamarix ramosissima), and a species related to fiber hemp (Cannabis sp.) grown in northern China. The diseased plants developed dense clusters of highly proliferating branches with shortened internodes; leaves on the affected branches were greatly reduced in size; and some branches and twigs suffered dieback. Results from nested polymerase chain reactions (PCR), performed by using phytoplasma-universal 16S rDNA primers, revealed that all diseased plants were infected by phytoplasma. Subsequent restriction fragment length polymorphism (RFLP) analysis and nucleotide sequence analysis of cloned near full-length 16S rRNA genes suggested that phytoplasmas present in these diseased plants belong to three different phytoplasma groups. Ecological and evolutionary relationships of these new phytoplasmas and their impacts on ecosystems in the region are being assessed.