Phenazine-1-Carboxylic Acid (PCA), Produced for the First Time as an Antifungal Metabolite by Truncatella angustata, a Causal Agent of Grapevine Trunk Diseases (GTDs) in Iran

Abstract

The phytopathogenic fungus Truncatella angustata, associated with grapevine trunk diseases (GTDs) in Iran, produces the well-known secondary metabolite isocoumumarin (+)-6-hyroxyramulosin and surprisingly also phenazine-1-carboxylic acid (PCA). PCA, identified by spectroscopic (essentially 1 H NMR and ESI MS) spectra, is a bacterial metabolite well known for its antifungal activity and was found for the first time in T. angustata culture filtrates. The antifungal activity of PCA was assayed against four different fungi responsible for GTDs, Phaeoacremonium minimum, Phaeoacremonium italicum, Fomitiporia mediterranea, involved in grapevine esca disease, and Neofusicoccum parvum, responsible for Botryosphaeria dieback. The activity was compared with that of the known commercial fungicide, pentachloronitrobenzene, and the close phenazine. PCA and phenazine exhibited strong antifungal activity against all phytopathogenic fungi, inhibiting the fungal growth by about 90−100% and 80−100%, respectively. These results suggested that T. angustata could use PCA to compete with other phytopathogenic fungi that attack grapevine and thus PCA could be proposed as a biofungicide against the fungi responsible for grapevine esca and Botryosphaeria dieback diseases.

Phytotoxins Produced by Two Biscogniauxia rosacearum Strains, Causal Agents of Grapevine Trunk Diseases, and Charcoal Canker of Oak Trees in Iran

“…The grapevine strain of B. rosacearum IRAN 4194C produced only one metabolite, while the other four compounds were isolated from the oak strain B. ros rum IRAN 4287C. They were identified as meso-2,3-butanediol, nectriapyrone, (3 methylmellein, (3R)-5-methy-6-methoxymellin, and tyrosol (1-5, Figure 1) by compa of their 1 H and 13 C NMR and ESI MS spectra, and were needed the specific optical tions with the data already reported in literature (see below). 6), (3R,4R)-4-hydroxymellein (7), (3R,4S) droxymellein ( 8), (3R)-6-hydroxymellein (9), and (3R)-4-methoxymellein (10).…”

“…(3R)-5-Methylmellin was characterized by 1 H and 13 C NMR and ESI MS spectra, but also by measuring its specific optical rotation, which is in agreement with the value previously reported by Okuno et al, 1986 [35]. In particular, its 1 H NMR spectrum showed a singlet at δ 10.98 due to a hydroxyl group at C-8 hydrogen bonded with the C-1 carbonyl group and two doublets (J = 8.4 Hz) at δ 7.28 and 6.82, which are typical signals of two ortho-coupled aromatic protons (H-6 and H-7, respectively) of a tetrasubstituted benzene ring with H-7 hupfield shifted for the electronic effect of the ortho-located HO-C8.…”

“…The symptoms of the same disease in Iran were also induced by Didymella glomerata and Truncatella angustata, which synthesized the phytotoxic 5-dihydroxymethylfuran and (+)-6-hydroxyramulosin respectively [12]. T. angustata also produced, probably as an antagonist, phenazine-1-carboxylic acid (PCA), which showed antifungal activity against four different fungi responsible for GTDs: Phaeoacremonium minimum, Phaeoacremonium italicum, and Fomitiporia mediterranea, involved in grapevine esca disease, and Neofusicoccum parvum, responsible for Botryosphaeria dieback [13].…”

Draft Genome Sequence of Truncatella angustata (Anamorph) S358

“…It is common as an endophyte or pathogen of vascular plants in both temperate and tropical regions ( 3 , 4 ). It infects stems ( Vitis [ 5 , 6 ], Vaccinium [ 7 ]), leaves ( Rosa [ 8 ], Parthenocissus [ 3 ], Populus [ 9 ]), fruits ( Malus [ 10 ], Olea [ 11 ]), and roots ( Vitis [ 12 ]) and is also a candidate for biological control of plant diseases ( 9 , 12 ). In addition to plants, this fungus was also isolated from marine sponges ( 13 ), humans ( 4 ), and as a pathogen from insects ( 14 ).…”

“…In addition to plants, this fungus was also isolated from marine sponges ( 13 ), humans ( 4 ), and as a pathogen from insects ( 14 ). T. angustata cultures showed several secondary metabolites with potential for application in biotechnology or medicine, e.g., α-pyrone-based analogs ( 15 ), phenazine-1-carboxylic acid with antifungal activity ( 6 ), ramulosin derivates with a broad range of biological activities ( 14 , 16 ), and truncateols, isoprenylated cyclohexanols with antiviral activity ( 15 , 17 ). In culture supernatants, isolate S358 showed activities of several oxidoreductases, including those of unspecific peroxygenase and laccase.…”