Báo cáo khoa học: "Effects of decline and/or air pollution on the terpene metabolism of Picea abies needles"

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Effects of decline and/or air pollution on the terpene metabolism of Picea abies needles A. Saint-Guily CNRS UA568, Unii de Bordeaux I, 33405 ersitd l Laborafoire de Physiologie Cellulaire V6g6tale, Talence Cedex, France Introduction by fungi (Cheniclet, 1987) or treatment with herbicides(Brown and Nix, 1975). The intention of this study was to eluci- The terpene metabolism (mevalonic acid date a possible relationship between the pathway) is a secondary metabolism pres- stress factors and variation in terpene ent in all plants. Terpenes are elaborated a metabolism. by successive condensation of isoprene units (C C and C terpene molecules 15 ). 5 10 are the main constituents of the volatile oils. These volatile terpenes are formed in secretory systems. Leucoplasts, non- Materials and Methods green plastids (Carde, 1984), are involved in their synthesis (Gleizes et al., 1983). In Different samples of needles were collected in conifer needles, these plastids are local- the spruce (P. abies) stands which were located ized in the epithelial cells of the subepider- in the Donon forest where 3 decline classes mal resin ducts. In Picea abies needles, were defined with respect to needle loss: class the secretory ducts are longitudinal and 2 (0-10% needle loss), class 3a (10-20%) and class 3b (35-50% with yellowish chlorosis). discontinuous. Needles of 3 consecutive yr from about 12 trees Forest decline is an important problem of each decline class were collected. The other which appears in several countries in samples of 5 yr old clones ("lac de Constance" (LC), "G6rardmer" (GER), "Istebna" (IST) were Europe and North America (McLaughlin, collected in the open top chambers of Montar- 1985). Most of the damaged forests are don and Donon. These plants were placed coniferous forests containing mainly under controlled conditions of air pollution spruce (Picea). Among the potential which were equivalent to the pollution recorded in the Donon forest. The 3 clones were placed causes of forest decline, air pollution has in air-filtered open top chambers or fumigated received particular attention (McLaughlin, with ozone (0 or sulfur dioxide (S0 alone or ) 3 ) 2 1985). Previous studies have shown that a mixture. In Montardon, a mobile roof protects the resin content of pine tissues greatly the trees from the rain. increases after mechanical or chemical Cytological observations were made with an injuries: wounding (Vassiliev and Carde, electron microscope. RuBPCase was localized 1976), infestation by insects and infection on ultrathin sections using immunogold labeling
techniques (Shaw and Henwood, 1985). The leucoplastidial volume density (LVD) (% of the cell volume occupied by leucoplasts) was esti- mated using a morphometric technique (Weibel, 1969). For analytical studies, oxygenated and hydro- carbon terpene fractions were separated on a silica column after pentane extraction and ana- lyzed with a gas chromatograph, using an apo- lar capillary column (Belingheri et al., 1988). A ’desorption concentration injection’ system (DCI, Delsi, France) was also used. About 5 needles were inserted into a heating block. The volatile compounds were swept by a carrier gas For each pair of classes the sample statistic T’ was and trapped in a tenax cartridge attached calculated. directly to the injector of the gas chromatogra- a value of the studentized augmented range critical phic apparatus (the injection consists of a ther- table: 00 !a.!2o) = 5 3.68 .05 mal desorption of the trapped compounds). The statistical evaluations of our data includ- an analysis of variance and a technique for ed testing all differences between pairs of means the LVD was different between the trees (multiple comparisons among pair of means: V- from Montardon and these from Donon method) (Spjotvoll and Stoline, 1973; Sokal and Rohlf, 1981 ). experiments. In the first case, the LVD was about 20% of the cell volume and no significant difference between trees fumigated with Cytological studies 0 S0 0 + S0 or charcoal-filtered air 323 2 ,, could be shown. Samples from Donon showed a higher Study of the leucoplastidome LVD for fumigated trees (24%) than for non-fumigated ones (13%). Leucoplastidome and decline In the Donon forest, the mean volume Study of the chloroplasts (RuBPCase densities of leucoplasts were 10% for the labeling) ’healthy’ trees and 15, 18 and 19% for the classes 2, 3a and 3b, respectively. Results of the T!method are presented in Table I. About 20 plastids were investigated on The pairs of damaged classes (2-3a, ultrathin sections for each decline state. 2-3b and 3a-3b) did not show any signifi- Variance analysis of these results verified cant differences between each other. But that RuBPCase labeling was not equiva- a significant difference did exist between lent for the different classes. The average the LVD of healthy trees and the LVD of all densities of the gold labeling (number of the other classes. gold particles per ,um of chloroplast 2 section) was 96 for ’healthy’ trees and 126, 121 and 59 for classes 2, 3a and 3b, Leucoplastidome and air pollution respectively. Only the 3b state showed significant differences with the 3 other For spruces with air pollutants fumigated classes (Table II). in open top chambers, the estimation of
patterns found in these needles were upon the origin of the plants dependent and not upon on the conditions of pol- lution. Discussion are significant differences between There leucoplastidial volume density of ’heal- the thy’ and damaged trees of the Donon forest. But the increase of the LVD and the decline of the trees did not seem to corre- late to any variation of terpene composi- tion in the needles of P. abies. Therefore, the LVD differences could be due to a shif- ting of cell differentiation in relation to the Terpene composition different localizations of the healthy and damaged tree classes. The lower labeling density of RuBPCase for the trees with Donon forest: declined trees bleached needles (state 3b) would be due No significant variation of terpene compo- to an irreversible disturbance of the me- sition was observed in correlation with the tabolism. But another experiment with a decline. must be done in larger plastid sampling order to confirm this first result. Open top chambers In the open t.op chambers of the Montar- don forest, there was no change of the The investigations of needle samples of leucoplastidial density and of the composi- IST from the Donon forest showed a tion of the terpene hydrocarbons. In nee- constant terpene hydrocarbon composi- dle samples from the Donon open top tion. In a polluted atmosphere, the propor- chambers, the decreased LVD was cor- tion of bornyl acetate increased, while the related to changes in the composition of proportion of camphor decreased. The 2 the oxygenated compounds for IST. The other clones (GER and LC) presented terpene composition of GER and LC was larger proportions of pinene and cam- also modified. These results suggest that phene and smaller proportions of limon- fumigation and natural rain are necessary ene in needles of fumigated trees. to produce a modification of the terpene In the Montardon forest, the terpene metabolism under controlled conditions. composition of IST and LC was indepen- dent of air pollution conditions during the growth of the needles. For GER the concentrations of limonene and bornyl References acetate seemed to be different between fumigated and non-fumigated trees. Belingheri L., Pauly G. & Gleizes M. (1988) Ter- fully grown needles, dif- However, on pene hydrocarbons from Citrofortunella mitis ferences in the terpene composition were fruits and leaves. Plant PhysioL Life Sci. Adv. 7, no longer observed. The varying terpene 101-103
Brown C.L. & Nix L.E. (1975) Uptake and complex, ATP synthase and ribulose 1,5-bis- transport of paraquat in slash pine. For. Sci. 21, phosphate carboxylase/oxygenase. Planta 165, 359-364 333-339 Carde J.P. distinct kind of {1984) Leucoplasts: a Sokal R.R. & Rohlf F.J. (1981) In: Biometry. organelles lacking typical 70S ribosomes and W.H. Freeman and Co., New York, pp. 859 free thylakoids. Eur. J. Cetl Biol. 34, 18-26 Cheniclet C. (1987) Effects of wounding and Spjotvoll E. & Stoline M.R. {1973) An extension fungus inoculation on terpene producing sys- of T-method of multiple comparison to include tems of maritime pine. J. Exp. Bot. 38, 1557- the cases with unequal sample sizes. J. Am. 1572 Stat. Assoc. 68, 975-978 Gleizes M., Pauly G., Carde J.P., Marpeau A. & Vassiliev A.E. & Carde J.P. (1976) Effects du Bernard-Dagan C. (1983) Monoterpene hydro- gemmage sur l’ultrastructure des cellules s6cr6- carbon biosynthesis by isolated leucoplasts of trices des canaux de 1’6corce des tiges de Citrofortunella mitis. Planta 159, 373-381 Pinus sylvestris L. et Picea abies (L.) Karst. McLaughlin S.B. (1985) Effects of air pollution Protoplasma 89, 41-48 on forests. A critical review. Air Pollut Control Assoc. 35, 512-534 Weibel E.R. (1969) Stereological principles for Shaw P.J. & Henwood J.A. {1985) Immuno-gold morphometry in electron microscopic cytology. localization of cytochrome f, light-harvesting Int Rev. Cytol. 26, 235-302