Experimental proofs regarding the association of cell wall deficient bacteria (mycoplasmalike organisms, phytoplasmas) with grapevine yellows disease in Romania

摘要

A study was performed on Grape yellows from 2008-2010, in five commercial grapevine growing regions in Romania. The presence of typical yellowing symptoms resembling Flavescence dorée and Bois noir diseases, described in West Europe, and on other continents, were detected on Vitis vinifera cvs. Chardonnay, Hamburg, Merlot, Feteasca regala, Cabernet Sauvignon, and Pinot Noir. Natural foci with Convolvulus arvensis, with symptoms of stolbur, Cichorium inthybus and Taraxacum officinale with symptoms of yellowing and virescence were detected in South of Romania and Trifolium repens with symptoms of clover phyllody and clover dwarf (aster yellows) were detected in Transylvania. Insect vectors as Hyalesthes obsoletus,Reptalus panzeri, Dictyophara europaea, Scaphoideus titanus, Macrosteles laevis and M. viridigriseus were detected also in natural foci. The vector H. obsoletus collected from grapevine cultivars transmitted stolbur MLO to periwinkle plants. By electron microscopy, on ultrathin sections, structures resembling cell wall deficient bacteria (MLOs, phytoplasma) were detected in the sieve elements of grapevine, and in the sediment of purified material. Using a polyclonal antiserum raised in rabbits with Aster yellows antigen, growth in artificial media, an indirect dot blot immunoassay (ELISA) technique was used and etiological agent as stolbur and aster yellows were identified. These results are first experimental proofs regarding the association of stolbur and aster yellows with grape yellows in Romania.