The phytopathogen Pseudomonas syringae produces the phytotoxin coronatine (COR) as a major virulence factor. COR and its precursor, coronafacic acid, function as molecular mimics of the plant signaling molecule jasmonate. A 32.8-kb plasmid-borne gene cluster mediates COR biosynthesis, which is optimal at 18 degrees C and non-detectable at 28 degrees C, the optimal growth temperature for P. syri...

Studies were conducted to determine the role of 3-methylthioproprionic acid (MTPA) in the pathogenicity of potato stem canker, Rhizoctonia solani, and the concentrations required to inhibit growth of R. solani under laboratory and plant house-based conditions. The experiments were laid out in a completely randomized design with five treatments and five replications. The treatments were 0, 1, 2,...

Aim. For the purpose of correct species and internal identification isolated strains bacteria that cause walnut leaf spotting, molecular biological genetic detection their ability to synthesize phytotoxin syringomycin have been carried out. Methods. It has used microbiological (PCR) methods. Results. The presence (syrD) secretion genes was established in spot pathogen typical strain Pseudomonas...

Several diketopiperazines have been isolated from liquid cultures of Alternaria alternata, the causal agent of black leaf blight of spotted knapweed, Centaurea maculosa Lam. One of these compounds, maculosin [the diketopiperazine cyclo(-L-Pro-L-Tyr-)], was active in the nicked-leaf bioassay at 10(-5) M; synthetic maculosin possessed chemical and biological activities identical to those of the n...

Beni Tal* and David J. Robeson A RCO Plant Cell Research Institute, 6560 Trinity Court, Dublin, CA 94568—2685, USA Z. Naturforsch. 41c, 1032—1036 (1986); received July 16/August 12. 1986 Pyrenocine A, Phytotoxin, Fungal M etabolite, Alternaria, Helianthus tuberosus A previously undescribed species of Alternaria was isolated from the leaves of Helianthus tuberosus bearing necrotic lesions. W hen...

Phytotoxic material has been isolated from liquid cultures of Ceratocystis ulmi. One component of the material has been obtained in pure form and has proved to be a rather thermostable glycoprotein. This compound induced disease symptoms, similar to those produced by the fungus itself, in elm sprouits and trees.