DETECTION OF ERWINIA-HERBICOLA PV. GYPSOPHILAE IN GYPSOPHILA PLANTS BY PCR

Three PCR primer pairs, based on the cytokinins (etz) or IAA biosynthe tic genes, were used for detecting Erwinia herbicola pv. gypsophilae i n Gypsophila paniculata plants. The primers were specific to all gall- forming E. herbicola strains and distinguished them from saprophytic s trains associated with gypsophila plants or from other gall-forming ba cteria. In pure culture of the pathogen, less than one bacterial cell was detected with nested PCR using the etz primers - an increase of 10 0-fold in sensitivity as compared with single-round PCR. In the presen ce of plant extract a reduction of tenfold in sensitivity was observed by nested PCR. When cells were grown on a semi-selective medium prior to PCR (Bio-PCR), five cells from pure culture of the pathogen were d etected. The bacteria could be detected by nested-PCR or Bio-PCR in sy mptomless gypsophila cuttings after 7 days. The Bio-PCR procedure desc ribed in this study can be used to establish disease-free nuclear stoc k of mother plants of gypsophila.