Ceratocystis toxins

Polyketides of this group are either monocyclic compounds, e.g., eugenone, Ceratocystis toxins, or bicyclic substances, e.g., citrinin, and possess a six-mem-bered carbocyclic ring. Compounds with seven-membered rings (tropoplones, e.g., sepedonin) also occur in nature. 

Sepedonin is involved in the uptake and transport of Fe + (E 2.2). Citrinin is a carcinogenic produced in several molds. The Ceratocystis toxins cause the Dutch elm disease (E 5.4). 

Polyketides Ceratocystis toxins (D 3.3.2) Products of Ceratocystis ulmi, causing Dutch elm disease... 

P.S. Russo, F.D. Blum, J.D. Ipsen, Y.J. Abul-Hajj and W.G. Miller, Solubility and surface activity of the Ceratocystis ulmi toxin cerato-ulmin, Physiol. Plant Path. 19 (1981) 113-126. 

S. Takai and W.C. Richards, Cerato-ulmin, a wilting toxin of Ceratocystis-ulmi, Isolation and some properties of cerato-ulmin from culture of C.-ulmi, Phytopath. Z. 91 (1978) 129-146. 

Dutch elm disease, caused by the fungus Ceratocystis ulmi, is disseminated by a bark beetle of the genus Scolytus. The fungus produces toxins that cause necrotic lesions and leaf wilting. These toxins consist of a mixture of glycoproteins and three low-molecular-weight phenolic compounds (Fig. 5.25) (Claydon et al., 1974 Harbome, 1982, 1986 Wood et al., 1972). 

As discussed previously see Chapter 5), pathogenic bacteria and fungi synthesize a number of compounds that help to break down host tissues and to weaken the host plant. Similar phytotoxins, especially those produced by bacteria, are peptides typically with molecular weights less than 600. However, in contrast to the compounds of fungi, most bacterial toxins exhibit an overall lack of specificity (Mitchell, 1981). In some cases, these phytotoxins are produced in conjunction with phytotoxins from other biosynthetic groups of compounds. For example, in addition to the polyketide-derived compounds involved in the attack on elm trees by Ceratocystis ulmi, phytotoxic glycoproteins are also released (Harbome, 1988 Wood et al., 1972). 

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