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

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Light-quality and -quantity effects on monoterpene-medi- ated photo-bleaching of conifer needles J. Franzen K. Gross M. Bonzon 23 1 E. 1 Wagner Institutes 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 (Gross monoterpenes, the characteristic products et al., 1988): fumigation of spruce (Picea of secondary metabolism in conifers, abies (L.) Karst.) seedlings and young could 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 of are kept strictly separated from the cyto- ’montane yellowing’. With the experiments plasm (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- ce et 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 their storage compartments. In a kind of auto- catalytic fashion, the thus liberated mono- terpenes can induce further changes in Materials and Methods membrane structure which can influence the membrane-bound electron transport. In the various fumigation experiments, 3 mo old The inhibition of respiration and photosyn- spruce seedlings were incubated in glass ves- sels with 100 pl of /3-pinene per I of air. This thesis by the monoterpene /3-pinene had concentration of monoterpene is comparable to been demonstrated earlier (Douce et al., the levels stored in needles (see Sch6nwitz et 1978; 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, the duction 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 a irrigated with tap water. Cultivation took place in kaya, 1988). glass vessels in continuous white light (16 W/ The incubators were placed for 48 h in ). 2 M In white light/dark cycles, chlorophyll b the various light environments in continuous and carotenoids were increased over the light or in 12:12 h cycles of light and dark at dark controls, while blue, red and far-red 298°K. After fumigation, 5 seedlings were com- light conditionsalso led to higher levels of bined for each sample and analyzed for their chlorophyll a. The increase in red light pigment 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 intensity copherol was extracted in n-hexane and quanti- white light given in light/dark cycles did not fied 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), since seedlings were grown at lower light inten- sity prior to the experimental treatment. Results and Discussion Photodestruction of pigments primarily affected chlorophyll a. Accumulation of The results are summarized in Table I. b depended strongly upon chlorophyll The data on the non-fumigated seedlings membrane biogenesis. Grana develop- show - a light-dependent accumulation of ment in conifers was also stimulated by pigments, a well-known physiological far-red light (Tyskiewicz et al., 1979). Light
quality-dependent differences in chloro- References phyll b accumulation might result from differences in membrane biogenesis also Carde J.P., Bernard-Dagan C. & Gleizes M. dependent upon light quality. Earlier (1980) Membrane systems involved in synthe- screening experiments indicated an in- sis and transport of monoterpene hydrocarbons in pine leaves. In: Biogenesis and Function of crease in pigment content of chloroplasts Plant Lipids. (Mazliak P., Benveniste P., Costes after sublethal treatments with P-pinene in C. & Douce R., eds.), Biochemical Press, white light/dark cycles. Amsterdam, pp. 441-444 Depending upon light-quality, -quantity Douce R., Neuburger M., Bligny R. & Pauly G. (1978) Effects of /!pinene on the oxidative prop- and light/dark cycles, the fumigation with erties of purified intact plant mitochondria. In: /3-pinene modified pigment and a-tocophe- Plant Mitochondria. (Ducet G. & Lance C., eds.), rol levels (Table I). Fumigation with j3-pi- 4 Biochemical Press, Amsterdam, pp. 207-214 led to increase in chl b and in nene car an Gleizes M., Pauly G., Carde J.P., Marpeau A. & (D), (wUD), (rUD) and (bUD). However, in Bernard-Dagan C. (1983) Monoterpene hydro- (wL), (WUD) and (BL), P-pinene strongly carbon biosynthesis by isolated leucoplasts of reduced pigment levels. The increase of Citrofortunella mitis. Planta 159, 373-381 pigment content with P-pinene fumigation Gross K., Vollbrecht P., Franzen, J., Dietz J. & Wagner E. (1988) Untersuchungen zum mecha- might indicate the triggering of anti-oxidant nismus der neuartigen waldschäden: hemmung defense mechanisms. Reduction in pig- der photosynthese und vergilbung von fichten- ment content with j3-pinene fumigation keimlingen und -jungpflanzen durch begasung occurred under conditions of light ’stress’. mit P.pinen. Allg. Forst Jagdz. 159, 45-49 As shown earlier (Gross et al., 1988), this Kasemir H. & Mohr H. (1981) The involvement effect correlated positively with the j3- of phytochrome in controlling chlorophyll and 5- aminolevulinate formation in a gymnosperm pinene concentration. Fumigation with j3- seedling (Pinus sylvestris). Planta 152, 369 pinene reduced the level of a tocopherol Lichtenthaler H.K. (1987) Chlorophylls and in the dark controls (D). Low intensity of carotenoids: pigments of photosynthetic bio- white light (wL), red light (rUD, RL) and membranes. Methods Enzymol. 148, 350-382 far-red light (fr/D) increased a-tocopherol Pauly G., Douce R. & Carde J.P. (1981) Effects levels. Under conditions of j3-pinene- of /3-pinene on spinach chloroplast photosyn- mediated reduction of pigment contents, thesis. 1. PflanzenphysioL 104, 199-206 a-tocopherol levels were also strongly Sch6nwitz R., Merk L. & Ziegler A. (1987) Natu- reduced (wL, WUD). These results in- rally occurring monoterpenoids in needles of dicate differential modulation of a-toco- Picea abies L. Karst. Trees 1, 88-93 pherol synthesis and turnover by different Tyszkiewicz E., Nicolic D., Popovic R. & Saric photoreceptor systems and require further M. (1979) Photophosphorylation and ultrastruc- tural development in Pinus nigra chloroplasts, detailed investigations. grown under different spectral composition of light. Physiol. Plant. 46, 324-329 Voskresenzkaya N.P. (1988) Photoregulatory Acknowledgments reactions and activity of the photosynthetic apparatus. Sov. Plant Physiol. 34, 538-550 This work was supported by the Bundesmini- Wagner E., Vollbrecht P., Janistyn B., Gross K. sterium fOr Forschung und Technologie (con- & Woerth J. (1987) Monoterpen-vermittelte tract no. 0339214A4) and F. Hoffmann-La zerst6rung des photosyntheseapparates von Roche & Co. The responsibility for the contents umen. g waldb Allg. Forstz. 42, 705-708 rests with the authors. We are indebted to Mrs. Wild A. (1988) Licht als streBfaktor bei B. Rossi for her technical help with the determi- umen. g waldb Naturwiss. Rundsch. 41, 93-96 nation of tocopherol.