Cerato-ulmin: A Unique Wilt Toxin of Instrumental Significance in the Development of Dutch Elm Disease

Abstract

The unique wilt toxin cerato-ulmin has been documented, covering its initial discovery and sequential experimental data to support its instrumental significance in the development of Dutch elm disease. Characterization of cerato-ulmin in view of its pathological implications for host specificity has brought up points that strongly suggest that cerato-ulmin is involved in Ophiostoma ulmi pathogenesis: 1) cerato-ulmin is produced only by O. ulmi, the Dutch elm disease pathogen, 2) cerato-ulmin causes symptoms of toxicity both external and internal that are similar to those of Dutch elm disease, 3) the toxicity of cerato-ulmin is selective and is highest with hosts of the pathogen, 4) high levels of cerato-ulmin apparently enhance the aggressiveness of O. ulmi, 5) cerato-ulmin affects host physiology, largely in a host specific manner, by increasing respiration rates and plasma membrane permeability; similar symptoms are observed in hosts affected by Dutch elm disease, in accordance with host susceptibility to Dutch elm disease, 6) in vitro production of cerato-ulmin is correlated with pathogenicities of O. ulmi wild-type isolates and, 7) cerato-ulmin is produced in vivo at relatively early stages in the development of external symptoms of Dutch elm disease.