Gulypyrones A and B and phomentrioloxins B and C produced by Diaporthe gulyae, a potential mycoherbicide for saffron thistle (Carthamus lanatus)

Andolfi, Anna and Boari, Angela and Evidente, Marco and Cimmino, Alessio and Vurro, Maurizio and Ash, Gavin and Evidente, Antonio (2016) Gulypyrones A and B and phomentrioloxins B and C produced by Diaporthe gulyae, a potential mycoherbicide for saffron thistle (Carthamus lanatus). Journal of Natural Products , 78 (4). pp. 623-629. ISSN 0163-3864

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Abstract

A virulent strain of Diaporthe gulyae, isolated from stem cankers of sunflower and known to be pathogenic to saffron thistle, has been shown to produce both known and previously undescribed metabolites when grown in either static liquid culture or a bioreactor. Together with phomentrioloxin, a phytotoxic geranylcyclohexenetriol recently isolated from a strain of Phomopsis sp., two new phytotoxic trisubstituted α-pyrones, named gulypyrones A and B (1 and 2), and two new 1,O- and 2,O-dehydro derivatives of phomentrioloxin, named phomentrioloxins B and C (3 and 4), were isolated from the liquid culture filtrates of D. gulyae. These four metabolites were characterized as 6-[(2S)2-hydroxy-1-methylpropyl]-4-methoxy-5-methylpyran-2-one (1), 6-[(1E)-3-hydroxy-1-methylpropenyl]- 4-methoxy-3-methylpyran-2-one (2), 4,6-dihydroxy-5-methoxy-2-(7-methyl-3-methyleneoct-6-en-1-ynyl)cyclohex-2-enone (3), and 2,5-dihydroxy-6-methoxy-3-(7-methyl-3-methyleneoct-6-en-1-ynyl)cyclohex-3-enone (4) using spectroscopic and chemical methods. The absolute configuration of the hydroxylated secondary carbon of the 2-hydroxy-1-methylpropyl side chain at C-6 of gulypyrone A was determined as S by applying a modified Mosher’s method. Other well-known metabolites were also isolated including 3-nitropropionic, succinic, and p-hydroxy- and p-methylbenzoic acids, p-hydroxybenzaldehyde, and nectriapyrone. When assayed using a 5 mM concentration on punctured leaf disks of weedy and crop plants, apart from 3-nitropropionic acid (the main metabolite responsible for the strong phytotoxicity of the culture filtrate), phomentrioloxin B caused small, but clear, necrotic spots on a number of plant species, whereas gulypyrone A caused leaf necrosis on Helianthus annuus plantlets. All other compounds were weakly active or inactive.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Files associated with this item cannot be displayed due to copyright restrictions.
Faculty / Department / School: Current - Faculty of Health, Engineering and Sciences - School of Agricultural, Computational and Environmental Sciences
Date Deposited: 07 Sep 2016 05:39
Last Modified: 07 Sep 2016 05:39
Uncontrolled Keywords: Ascomycota; Australia; Benzaldehydes; Carthamus; Cyclohexanols; Herbicides; Molecular Structure; Nitro Compounds; Propionates; Pyrones
Fields of Research : 06 Biological Sciences > 0607 Plant Biology > 060702 Plant Cell and Molecular Biology
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970106 Expanding Knowledge in the Biological Sciences
Identification Number or DOI: 10.1021/np500570h
URI: http://eprints.usq.edu.au/id/eprint/29680

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