Báo cáo khoa học: Hypoxylon mammatum toxins: possible involvement in canker development on

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Báo cáo khoa học: "Hypoxylon mammatum toxins: possible involvement in canker development on"Hypoxylon mammatum toxins:possible involvement in canker development on aspen S. Rebuffat 2I. Genetet J. Pinon B. Bodo 12 11 Pathologie ForestiAre, tNRACRF, Champenoux F-54280, Seichamps, and Laboratoire de2 Appliqu6e aux Corps Organisés, CNRS UA40i, 63, Museum National d’Histoire Naturetle, Chimierue Buffon, F-75231 Paris Cedex 05, France separated by elution of the XADIntroduction were with a methanol/water gradient: resin hymatoxins first eluted (about 40 mg/l of mammatum (Wahl.) MillerHypoxylon filtrate) and then neutral metabolites (a stem canker on aspen (Populuscauses a few mg/1). The chemical structures oftremula) and on some poplars of the Taca- these substances were determined byhamaca section (Pinon, 1976). The di- spectrometric methods (MS, IR, 1 D andsease is characterized by a flattened 2D NMR). Hymatoxins are unusual diter-sunken surface with a yellow orange mar- pene sulfates with a molecular mass ofgin. H. mammatum prevents host callu- about 400. The other toxin group is consti-sing. Hubbes (1964) found that diffusible tuted of trihydroxytetralones.substances from H. mammatum agar cul- To provide a clearer understanding oftures inhibited callus formation in wounds the pathotoxic features of H. mammatum,on aspen bark. Schipper (1978) and Ster- search for and characterization of in vivomer et aL, (1984) confirmed the possibility toxic metabolites were undertaken and thethat H. mammatum could produce toxins. data are reported herein.These compounds can be isolated by par-titioning into various organic solvents andchromatography. Culture age was alsosupposed to affect the kind and amount of Materials and Methodsmetabolites produced (Stermer et al.,1984). We have isolated and character- Purification procedureized 2 groups of toxins from culture filtrate Young aspen trees were obtained from breed-(Bodo et al., 1987). Optimum secretion ing programs (Lemoine, 1973). The trees werewas achieved within 6 wk of still culture on planted and inoculated with mycelium in 1981 (Pinon et al., 1988). After 6 yr, the H. mamma-wort medium. A technique has been de- tum trees were cut. Wood and bark samplesveloped to isolate the toxins from the fil- from both healthy and infected areas were col-trate by adsorption onto a neutral resin lected. Each sample was freeze-dried, ground(Amberlite XAD 4). Two groups of toxins and then kept at -20°C. 100 g of each sample extracted in a soxhlet apparatus with 10 leaves taken for each assay. Acetonewere weremethanol for 6 h. The extracts were concen- used control. (1°I°) was astrated and an aliquot of each sample was testedfor its toxicity using a leaf bioassay. The active were partially purified by chromatogra-extractsphy on Sephadex LH-20. The fractions obtained Results and Discussion reduced to dryness under vacuum.were When tested at a concentration of 1Leaf bioassay mg/ml, extracts from healthy wood and bark samples had no visible effects,Throughout the purification procedure, samples bioassayed by determining their effects onwere whereas those from infected wood andthe leaves according to ...