Submitted to: Plant Disease
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/24/2005
Publication Date: 4/1/2006
Citation: Widmer, T.L. 2006. Cryopreservation of synchytrium solstitiale in planta. Plant Disease. 90:429-432 Interpretive Summary: Yellow starthistle is a noxious weed that has invaded the United States from the Mediterranean region. It is a serious pest of pastures, rangelands, croplands, natural areas, and recreational areas. Chemicals can manage YST but because of economic and environmental issues other control methods are sought. A new fungus, causing orange to red galls, was isolated from leaves of yellow starthistle in France that is being investigated as a biological control agent against this weed. This article describes a method to store the fungus for a longer period of time below a freezing temperature. The impact of this study allows research on this fungus to continue even when the fungus is no longer found in the field.
Technical Abstract: The fungus Synchytrium solstitiale is a candidate for use as a biocontrol agent against Centaurea solstitialis. Although this obligate parasite can be propagated in planta under laboratory conditions, a method was needed to preserve cultures for longer periods of time for routine biological studies and shipping to other laboratories. Infected C. solstitialis tissue was immersed in water, water plus iprodione, methanol, ethylene glycol, DMSO, glycerol, skim milk, trehalose, or mineral oil and subjected to different temperatures for various periods of time. Infected tissue stored for 3 months at -2oC in 0.5 M sucrose released active zoospores. Some treatments protected the viability of the fungus for a shorter period of time while other treatments completely inhibited release. The effect of different fungicides on zoospore release was also measured. Cycloheximide and benomyl completely inhibited zoospore release or released nonmotile zoospores from tissue stored in these two chemicals, respectively. A few zoospores were released in suspensions of iprodione and propionic acid but were not motile. However, when tissue that was stored in iprodione or propionic acid was transferred to fresh distilled water abundant active zoospores were released. Overall, results obtained from this study demonstrate a technique for longer storage of S. solstitiale.