Cerato-ulmin Research Articles

Scanning electron microscope observations of internal symptoms of white elm following Ceratocystis ulmi infection and cerato-ulmin treatment

Internal vascular symptoms induced by Ceratocystis ulmi infection and cerato-ulmin (CU) in white elm (Ulmus americana) were observed under a scanning electron microscope. Symptoms caused by CU were indistinguishable from those caused by C. ulmi. The main symptoms observed were (i) edemalike surface wall alteration, (ii) granular deposit, (iii) pit membrane heaving, (iv) smooth coating, (v) bubble and (or) tylose formation, (vi) rough coating, (vii) droplet formation, and (viii) vessel plugging with calluslike material. Internal symptoms appeared earlier in CU treated elms (as early as 2 h after treatment) than in C. ulmi infected elms (10 h after infection).

Accumulation of the material containing the toxin cerato-ulmin on the hyphal surface of Ceratocystis ulmi

Recovery of cerato-ulmin (CU) in the water extract from intact hyphae of Ceratocystis ulmi proved that it is present on the hyphal surface. Degrees of the accumulation of unidentified material on the cell surface of hyphae, together with CU recovery, varied from high, among isolates classified as distinct in CU production, to unmeasurable, among isolates classified as negligible in CU production. There was a correlation between the accumulation of unidentified material on the hyphal surface as observed under the scanning electron microscope (SEM) and recovery of CU from hyphal colonies. Most of the accumulated material was water-extractable, as is CU, and it is therefore concluded that the material accumulated on the hyphae of isolates classified as distinct in CU production does, indeed, contain CU.

Relationship of the production of the toxin, cerato-ulmin, to synnemata formation, pathogenicity, mycelial habit, and growth of Ceratocystis ulmi isolates

Forty-seven isolates of Ceratocystis ulmi collected from Canada, the United States, the United Kingdom, France, the Netherlands, and Iran were classified with respect to their ability to produce cerato-ulmin (CU) and synnemata, their radial growth, mycelial habit, and pathogenicity.Twenty-nine isolates clearly produced CU in a measurable quantity while 18 isolates produced it only in trace quantities. In general, the former produced fluffy mycelium and were active in synnemata formation. They were aggressive in pathogenicity with one exception. The latter group of isolates generally produced waxy, yeastlike mycelium and formed very few synnemata. They were all nonaggressive in pathogenicity. Radial growth was generally higher among the isolates that produced CU in larger quantities than among those producing CU in trace quantities. The relationship between CU production and pathogenicity affords a method for estimating isolate pathogenicity without the need for host inoculation.

Evidence for the presence of the toxin cerato-ulmin in the synnema head fluid of Ceratocystis ulmi

The presence of cerato-ulmin (CU) in the synnema head fluid (HF) of Ceratocystis ulmi was shown by the results of light and scanning electron microscope observation and by demonstration of the assembling and disassembling of structures characteristic of CU in the HF. Further, through the combined application of acrylamide gel electrophoresis and double diffusion techniques, CU was detected as the major protein in the HF.