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The Phytopathogenic Mollicute-Insect Vector Interface: A Closer Look

December 1998 , Volume 88 , Number  12
Pages  1,351 - 1,358

Jacqueline Fletcher , Astri Wayadande , Ulrich Melcher , and Fengchun Ye

First, second, and fourth authors: Department of Entomology and Plant Pathology; and third author: Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater 74078

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Accepted for publication 12 June 1998.

Spiroplasma citri, transmitted by phloem-feeding leafhoppers, moves from the gut lumen through the gut wall, hemolymph, and salivary glands and multiplies in insect tissues. Nontransmissible lines were deficient in their ability to cross these barriers. Molecular analysis revealed extensive chromosomal rearrangements between the transmissible and nontransmissible spiroplasma lines including a large chromosomal inversion and deletions of about 10 kb at each inversion border. One open reading frame of the deleted region, cloned from the transmissible strain BR3-3X, encodes an integral membrane protein of 58 kDa that shares limited sequence similarity with major adhesin proteins of two zoopathogenic mycoplasmas. Adhesion of spiroplasmas to cultured leafhopper cells was inhibited by proteases, suggesting that adherence to host cells is mediated by spiroplasma membrane protein(s). A hypothetical model for insect transmission of phytopathogenic mollicutes is presented.

Additional keywords: Circulifer tenellus , phytoplasma , receptor .

© 1998 The American Phytopathological Society