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Didymella glomerata and Truncatella angustata associated with grapevine trunk diseases (GTDs) in Iran, were grown in vitro to evaluate the production of phytotoxic metabolites as potential pathogenicity determinants. 2,5-Dihydroxymethylfuran and (+)-6-hydroxyramulosin were isolated from the culture filtrates of D. glomerata and T. angustata , respectively. They were identified by physical and spectroscopic (essentially 1 D and 2 D 1 H and 13 C NMR and ESIMS) methods and X ray analysis. Both compounds induced significant necrosis and curling on the leaves of the host plant Vitis vinifera L. and the effects were concentration dependent. No effect was observed on the leaves of the non-host Solanum lycopersicum L.. plant.

A strain of Kalmusia variispora associated with grapevine trunk diseases (GTDs) was identified in Iran and induced disease symptoms on the host in greenhouse conditions. The grapevine pathogens are able to produce a plethora of toxic metabolites belonging to different classes of naturally occurring compounds. Two homogeneous compounds were isolated from the organic extract of K. variispora culture filtrates. They were identified by physic (specific optical rotation), and spectroscopic (essentially 1D 1 H and 13 C NMR and HR ESIMS) methods as the fungal polyketides massarilactones D and H ( 1 and 2 ). The unassigned absolute configuration of massarilactone D was unambiguously determined by X-ray diffractometric analysis. Massarilactones D and H showed phytotoxic activity on Vitis vinifera L. at two concentrations used and depending from the days of inoculation. Phytotoxicity is also increased when the 3,4,7- O,O',O"- triacetyl derivative of massarilactone D ( 3 ) was assayed on the host plant. This is the first report on the investigation of phytotoxic metabolites produced by K. variispora isolated from infected grapevine in Iran and they seem to be involved in the development of disease symptoms.

Two phytotoxic furan derivatives were isolated, together with the well-known fungal and plant phytotoxin tyrosol, from the culture filtrates of Stilbocrea macrostoma . This fungal pathogen isolated from Quercus brantii trees induced wood necrosis and decline symptoms on the host plant in Iran. The two furan derivatives, isolated for the first time from Stilbocrea macrostoma , were identified by spectroscopic methods (essentially 1 D and 2 D 1 H and 13 C NMR and ESIMS spectroscopy) as 5-hydroxymethylfuraldehyde and 2,5-dihydroxymethylfuran. The phytotoxic activity of the three metabolites was evaluated by leaf puncture assay on holm oak ( Quercus ilex L.) and tomato ( Lycopersicon esculentum L.) leaves. All compounds induced necrosis on holm oak leaves while very low toxicity was showed against tomato leaves. The two furan derivatives were more toxic than tyrosol and particularly 5-hydroxymethylfuraldehyde was the most phytotoxic compound.