No abstract

Trichoderma are ubiquitous soil fungi that include species widely used as biocontrol agents in agriculture. Many isolates are known to secrete several secondary metabolites with different biological activities towards plants and other microbes. Harzianic acid (HA) is a T. harzianum metabolite able to promote plant growth and strongly bind iron. In this work, we isolated from the culture filtrate of a T. harzianum strain a new metabolite, named isoharzianic acid (iso-HA), a stereoisomer of HA. The structure and absolute configuration of this compound has been determined by spectroscopic methods, including UV-Vis, MS, 1D and 2D NMR analyses. In vitro applications of iso-HA inhibited the mycelium radial growth of Sclerotinia sclerotiorum and Rhizoctonia solani. Moreover, iso HA improved the germination of tomato seeds and induced disease resistance. HPLC-DAD experiments showed that the production of HA and iso HA was affected by the presence of plant tissue in the liquid medium. In particular, tomato tissue elicited the production of HA but negatively modulated the biosynthesis of its analogue OPEN ACCESSMolecules 2014, 19 9761 iso-HA, suggesting that different forms of the same Trichoderma secondary metabolite have specific roles in the molecular mechanism regulating the Trichoderma plant interaction.

Interactions of glyphosate (N-phosphonomethylglycine) herbicide (GLY) with soluble fulvic acids (FAs) and humic acids (HAs) at pH 5.2 and 7 were studied by (1)H and (31)P NMR spectroscopy. Increasing concentrations of soluble humic matter determined broadening and chemical shift drifts of proton and phosphorus GLY signals, thereby indicating the occurrence of weak interactions between GLY and humic superstructures. Binding was larger for FAs and pH 5.2 than for HAs and pH 7, thus suggesting formation of hydrogen bonds between GLY carboxyl and phosphonate groups and protonated oxygen functions in humic matter. Changes in relaxation and correlation times of (1)H and (31)P signals and saturation transfer difference NMR experiments confirmed the noncovalent nature of GLY-humic interactions. Diffusion-ordered NMR spectra allowed calculation of the glyphosate fraction bound to humic superstructures and association constants (K(a)) and Gibbs free energies of transfer for GLY-humic complex formation at both pH values. These values showed that noncovalent interactions occurred most effectively with FAs and at pH 5.2. Our findings indicated that glyphosate may spontaneously and significantly bind to soluble humic matter by noncovalent interactions at slightly acidic pH and, thus, potentially pollute natural water bodies by moving through soil profiles in complexes with dissolved humus.

a b s t r a c t 1 H NMR spectroscopy was employed to investigate the molecular quality of Aglianico red wines from the Campania region of Italy. The wines were obtained from three different Aglianico vineyards characterized by different microclimatic and pedological properties. In order to reach an objective evaluation of "terroir" influence on wine quality, grapes were subjected to the same winemaking procedures. The careful subtraction of water and ethanol signals from NMR spectra allowed to statistically recognize the metabolites to be employed in multivariate statistical methods: Principal Component Analysis (PCA), Discriminant Analysis (DA) and Hierarchical Clustering Analysis (HCA). The three wines were differentiated from each other by six metabolites: ␣-hydroxyisobutyrate, lactic acid, succinic acid, glycerol, ␣-fructose and ␤-d-glucuronic acid. All multivariate analyses confirmed that the differentiation among the wines were related to micro-climate, and carbonate, clay, and organic matter content of soils. Additionally, the wine discrimination ability of NMR spectroscopy combined with chemometric methods, was proved when commercial Aglianico wines, deriving from different soils, were shown to be statistically different from the studied wines. Our findings indicate that multivariate statistical elaboration of NMR spectra of wines is a fast and accurate method to evaluate the molecular quality of wines, underlining the objective relation with terroir.

No abstract