Báo cáo lâm nghiệp: Light-quality and -quantity effects on monoterpene-mediated photo-bleaching of conifer needles

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Light-quality and -quantity effects on monoterpene-mediated photo-bleaching of conifer needles...
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Báo cáo lâm nghiệp: "Light-quality and -quantity effects on monoterpene-mediated photo-bleaching of conifer needles"Light-quality and -quantity effects on monoterpene-medi-ated photo-bleaching of conifer needlesJ. Franzen K. Gross M. Bonzon 23 1 E. 1 WagnerInstitutes of I Biology 11 and2 University of Freiburg i.Br., F.R.G., and Silviculture,3 Institute of Plant Physiology University of Geneva (CH), Switzerland monoterpene-mediated changes of mem-Introduction branes. The result is a photooxidative bleaching of the chloroplast pigments.In earlier publications (Wagner et aL, In simulation experiments, we demon-1987; Gross et al., 1988) we showed that strated such monoterpene effects (Grossmonoterpenes, the characteristic products et al., 1988): fumigation of spruce (Piceaof secondary metabolism in conifers, abies (L.) Karst.) seedlings and youngcould play a role in forest decline. plants with P-pinene resulted in a monoter- Monoterpenes are synthesized in leuco- pene concentration- and photofluency-plasts at the basis of needles and are dependent destruction of chloroplast pig-transported into resin ducts where they ments resembling the phenomenon ofare kept strictly separated from the cyto- ’montane yellowing’. With the experimentsplasm (Carde et al., 1980; Gleizes et al, presented here, we investigate the influen-1983). In a working hypothesis (Wagner of light quality on monoterpene-medi- ceet al., 1987), we suggested that changes ated photo-bleaching of chloroplast pig-in membrane structure by air pollutants ments and on the levels of a-tocopherol.could liberate the monoterpenes from theirstorage compartments. In a kind of auto-catalytic fashion, the thus liberated mono-terpenes can induce further changes in Materials and Methodsmembrane structure which can influencethe membrane-bound electron transport. In the various fumigation experiments, 3 mo oldThe inhibition of respiration and photosyn- spruce seedlings were incubated in glass ves- sels with 100 pl of /3-pinene per I of air. Thisthesis by the monoterpene /3-pinene had concentration of monoterpene is comparable tobeen demonstrated earlier (Douce et al., the levels stored in needles (see Sch6nwitz et1978; Pauly et al., 1981The inhibition of al., 1987). In parallel to each fumigation experi-photosynthesis depends upon light inten- ment, a non-fumigated control was analyzed.sity and probably results from an overpro- Prior to the experimental treatments, theduction of oxygen free radicals due to seedlings had been cultivated in groups of 50 3:1 mixture of quartzsand and vermiculite adaptation (for review see Voskresenz-on airrigated with tap water. Cultivation took place in kaya, 1988).glass vessels in continuous white light (16W/ The incubators were placed for 48 h in).2M In white light/dark cycles, chlorophyll bthe various light environments in continuous and carotenoids were increased over thelight or in 12:12 h cycles of light and dark at dark controls, while blue, red and far-red298°K. After fumigation, 5 seedlings were com- light conditionsalso led to higher levels ofbined for each sample and analyzed for their chlorophyll a. The increase in red lightpigment content and a-tocopherol levels. Pigment determination was carried out in was less than in blue or in far-red light (cf.acetone according to Lichtenthaler (1987). To- Kasemir and Mohr, 1981).High intensitycopherol was extracted in n-hexane and quanti- white light given in light/dark cycles did notfied by HPLC on a Lichrosorb Si 60.5 !column favor pigment accumulation, possibly indi-with n-hexane and 3% ethylacetate. cative of light ’stress’ (Wild, 1988), sin ...