A new disease causing stunting and shoot proliferation in Gypsophila is associated with phytoplasma

Phytoplasma diseases have been identified in Israel in numerous species of various botanical families. The disease occurs in ornamentals, vegetables, field crops and fruit trees. In cut flowers, the disease was identified in Ranunculus spp., Celosia, Anemone and Limonium. In all these cases the disease was sporadic with no serious economical losses. In 2003, symptoms typical of a phytoplasma infection were observed in a large number of Gypsophila paniculata L. (i.e. baby's breath) plants grown in commercial fields in Israel. The symptoms include leaf yellowing, production of abundant long and narrow leaves, stunting, shoot proliferation, poor flower set and consequently reduce the yield of flowers by up to 80%. Examination of ultrathin sections of samples from diseased plants by electron microscopy revealed the presence of pleomorphic membrane-bound bodies in the phloem cells. Total nucleic acid was extracted from asymptomatic and symptomatic Gypsophila leaves. All leaf samples from twenty symptomatic plants consistently tested positive using a polymerase chain reaction assay (PCR) with phytoplasma universal primers (P1/P7) that amplify a 1.8-kb phytoplasma rDNA product and followed by nested PCR with R16F2n/R16R2 primers yielding a product of 1.2 kb. No PCR products were evident when DNA extracted from healthy plants was used as a template. Sequence analysis of the PCR products obtained from numerous preparations, associated with infected Gypsophila, clustered within one ribosomal group of phytoplasmas (16SrII), peanut witches' broom. This is the first published record of these phytoplasmas in Gypsophila in Israel. The present paper reports the outbreak of phytoplasma in Gypsophila grown in commercial fields in Israel, survey of potential insect vector(s) of phytoplasma and possible control strategies using screen barriers.