Influence of a Ceratocystis ulmi Toxin on Water Relations of Elm (Ulmus americana)

Abstract

branes (23), interference with stomatal regulation of transpiration (31), and reduction of flow through the stem by either vascular plugging (4) or an increase in the viscosity of the xylem sap (5).The purpose of this investigation was to study the effect of the glycopeptide toxin, isolated from C. ullni cultures, on the water balance and stem conductance of elm seedlings in order to elucidate the possible mode of action of the toxin in elm. We also tested whether dextrans similar in molecular weights to the toxin can mimic its action. MATERIALS AND METHODSCeratocystis ulmi (Buisman) C. Moreau, freshly isolated from infected Ulmus americana L. trees, was used in all experiments. Cultures were grown in liter amounts of medium (18) in Fernbach flasks at 23 C on a rotary shaker at 110 rpm. Cultures, harvested after 2 to 4 weeks, were filtered through Whatman No. 42 paper, then through a 0.45-,um Millipore filter and concentrated approximately 20-fold under vacuum at 40 C. One volume 95% (v/v) ethanol was added and the precipitate was discarded. The ethanol was then removed and the filtrate was concentrated another 2-fold using vacuum evaporation at 40 C. The concentrated filtrate was dialyzed against distilled water at 4 C for 24 hr with 2 changes of H20. To prevent microbial growth, 0.5% (v/v) chloroform was added to the H,O. The dialysate was discarded and 5 volumes of 95% (v/v) ethanol were added to the dialyzed solution. It was then placed in a freezer for at least 24 hr. The precipitate, i.e., the crude toxin, was collected by centrifugation at 10,000g for 10 min. The yield of crude toxin was approximately 100 mg liter-'. These methods were similar to those of Salemink et al. (18)

Breeding and scientific advances in the fight against Dutch elm disease: Will they allow the use of elms in forest restoration?

“…If the root system remains alive, root carbon reserves can be remobilized to resprout and trees sometimes experience cycles of resprouting and dieback for decades (Peterken and Mountford 1998). Xylem dysfunction is caused by tyloses, gels, gums and other compounds of host and pathogen origin that increase sap viscosity, clog pit membranes and occlude vessels (van Alfen and Turner 1975;Newbanks et al 1983;Ouellette and Rioux 1992).…”

Changes in Alfalfa Stem Conductance Induced by Corynebacterium insidiosum Toxin

“…From these data, it is evident that the effects of the toxin on the leaf H20 potential, stomatal conductance, and transpiration of alfalfa cuttings can best be explained as a result of the interference by the toxin of H20 flow through the vascular system of the cuttings. This interference to water flow was also found to be the mechanism whereby high molecular weight glycopeptides produced by Ceratocystis ulmi affect water relations of elm seedlings (13).…”

“…While indicating that the mode of action of the toxin was unknown, the same authors showed that it was more effective in causing wilting of tomatoes than amylopectin (mol wt = 70 X 106) or blue dextran (mol wt = 2 X 106), and thus they concluded that physical plugging of the transpiration stream was excluded as a possible mode of action and suggested that the toxin caused membrane damage in a similar manner to C. sepedonicum and C. michiganense (9). Our previous work (13) on the mode of action and suggested that the toxin caused membrane damage in a similar manner to C. sepedonicum and C. michiganense (9). Our previous work (13) and of 2 X 106 were also prepared at concentrations of 200 jug ml-' in H20 and filtered and degassed.…”

“…Our previous work (13) on the mode of action and suggested that the toxin caused membrane damage in a similar manner to C. sepedonicum and C. michiganense (9). Our previous work (13) and of 2 X 106 were also prepared at concentrations of 200 jug ml-' in H20 and filtered and degassed.…”

“…Iroquois) stems, 0.2 to 0.3 cm in diameter and 15 cm long, to test solutions was determined using a pressure chamber (10) as previously described (13). The stem segment, without leaves, was sealed into the pressure chamber with one end dipping into a test tube containing the test solution.…”