DETECTION AND IDENTIFICATION OF PHYTOPLASMAS IN YELLOWS-DISEASED WEEDS IN ITALY

Yellows-diseased plants of Crepis setosa (hawksbeard), Knautia arvensi s (field scabious), Convolvulus arvensis (field bindweed), Picris echi oides (bristly oxtongue), Echium vulgare (blueweed) and Calendula offi cinalis (pot marigold) collected in central and southern Italy were ex amined for phytoplasma infection by means of polymerase chain reaction (PCR) technology using universal phytoplasma primers directed to ribo somal sequences. The detected phytoplasmas were characterized and diff erentiated using restriction fragment length polymorphism analysis of PCR-amplified DNA. The phytoplasma detected in diseased pot marigold p lants was identified as a member of the aster yellows group and proved indistinguishable from a strain of the American aster yellows phytopl asma. The phytoplasma identified in diseased field bindweed plants is a putative new type of the stolbur group that differed from the typica l stolbur phytoplasma. Phytoplasmas detected in diseased hawksbeard, b lueweed and field scabious plants are all putative new members of the sugarcane white leaf group while the phytoplasma detected in diseased bristly oxtongue plants represents a new member of the faba bean phyll ody group. For hawksbeard and field scabious this is the first report on the occurrence of phytoplasma diseases, whereas phytoplasmas infect ing bristly oxtongue and blueweed have never been characterized before .