Abstract
The fluorescence of the chlorophyll associated with photosystem II was studied in seedling and flag leaves of Triticum species. Seedling leaves of the diploid species T. urartu had higher values of t (the normalised area over the fluorescence induction curve of DCMU treated leaves) than those of the other species studied which included hexaploid T. aestivum. However this difference was not evident when leaves were grown in a low light intensity (40 µmol quanta of photosynthetically active radiation m−2 s−1). The smaller total number of chlorophyll molecules per photosystem II reaction centre (chl/RCII) in T. urartu (177) as compared with the other species (mean 234) was deduced from the observed differences in t. As a consequence of its lower chl/RCII, despite slightly lower chlorophyll content (mg m−2), T. urartu had a greater density of reaction centres than the other species (2880 cf 2230 nmol m−2 of leaf). Consistent with the lower chl/RCII of T. urartu, it had a higher chlorophyll a/b ratio than the other genotypes. Seedling leaves of T. urartu had higher light saturated rates of photosynthesis than those of the other species, when grown at high light, a difference associated with reaction centre density.
In flag leaves, when the complications due to variable development and senescence patterns were eliminated, t of the diploid species including T. urartu was lower than that of T. aestivum. The lower apparent chl/RCII of T. urartu arose partly because the molar extinction coefficient of the chlorophyll in the leaves of T. urartu was greater than in T. aestivum. However, the density of PS II reaction centres was slightly lower for the diploid species studied because their chlorophyll contents were lower than the hexaploids.
The validity of the method for estimating chl/RCII from fluorescence transients is discussed. The possibility is considered that the difference in apparent chl/RCII of flag and seedling leaves of R. urartu as compared to the other five genotypes is a consequence of its different adaptive response to the spectral quality of the light.
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References
Alberte RS, McClure PR and Thornber JP (1976) Organisation of chlorophyll and photosynthetic unit size in isolated gymnosperm chloroplasts. Plant Physiol 58: 341–344
Arnon DI (1949) Copper enzymes in isolated chloroplasts. Polyphenaloxidase in Beta vulgaris. Plant Physiol 24:1–15
Austin RB, Morgan CL and Ford MA (in press) Photosynthesis rates and dry matter yields of diploid and hexaploid Triticum species
Austin RB, Morgan CL, Ford MA and Bhagwat SG (1982) Flag leaf photosynthesis of Triticum aestivum and related diploid and tetraploid species. Ann Bot 49: 177–189
Bartels PG and Watson CW (1978) Inhibition of carotenoid biosynthesis by fluridone and norflurazon. Weed Sci 26:198–203
Bunce JA, Patterson DT, Peet MM and Alberte RS (1977) Light acclimation during and after leaf expansion in soybean. Plant Physiol 60:255–258
Dunstone RL, Gifford RM and Evans LT (1973) Photosynthetic characteristics of modern and primitive wheat species in relation to ontogeny and adaptation to light. Aust J biol Sci 26:295–307
Evans LT and Dunstone RL (1970) Some physiological aspects of evolution in wheat. Aust J biol Sci 22:725–741
Haehnel W, Holzwarth AR and Wendler J (1983) Picosecond fluorescence kinetics and energy transfer in the antenna chlorophylls of green algae. Photochem and Photobiol 37:435–443
Lichtenthaler HK, Kuhn G, Prenzel U, Buschman C and Meier D (1982) Adaptation of chloroplast-ultrastructure and of chlorophyll-protein levels to high-light and low-light growth conditions. Z Naturforsch 37:464–475
Malkin S, Armond PA, Mooney HA and Fork DC (1981) Photosystem II photosynthetic unit sizes from fluorescence induction in leaves. Plant Physiol 67:570–579
Malkin S and Fork DC (1981) Photosynthetic units of sun and shade plants. Plant Physiol 67:580–583
Malkin S and Kok B (1966) Fluorescence induction studies in isolated chloroplasts. Number of components involved in the reaction and quantum yields. Biochim Biophys Acta 126:413–432
Malkin S, Morgan CL and Austin RB (1986) Estimation of the light distribution between photosystems I and II in intact wheat leaves by fluorescence and photoacoustic measurements. Phot Res 7: 257–267
Malkin S and Siderer Y (1974) The effect of salt concentration on the fluorescence parameters of isolated chloroplasts. Biochem Biophys Acta 368:422–431
Melis A and Brown JS (1980) Stoichiometry of system I and system II reaction centres and of plastoquinone in different photosynthetic membranes. Proc Natl Acad Sci 77:4712–4716
Miginiac-Maslow M, Hoarau A and Moyse A (1979) Hill reaction studies with protoplasts from cultivated wheats and their wild relatives. Z Pflanzenphysiol Bd 95:95–104
Patterson DT, Bunce JA, Alberte RS and Van Volkenburgh E (1977) Photosynthesis in relation to leaf characteristics of cotton from controlled and field environments. Plant Physiol 59: 384–387
Telfer A, Allen JF, Barber J and Bennett J (1983) Thylakoid protein phosphoryation during state 1 — state 2 transitions in osmotically shocked pea chloroplasts. Biochim Biophys Acta 722:176–181
Williams BA, Gurner PJ and Austin RB (1982) A new infra-red gas analyser and portable photosynthesis meter. Phot Res 3:141–151
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Morgan, C.L., Austin, R.B. Analysis of fluorescence transients of DCMU-treated leaves of Triticum species to provide estimates of the densities of photosystem II reaction centres. Photosynth Res 7, 203–219 (1986). https://doi.org/10.1007/BF00014675
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DOI: https://doi.org/10.1007/BF00014675