Photosynthetic activity, chloroplast ultrastructure, and leaf characteristics of high-light and low-light plants and of sun and shade leaves

Abstract

The photosynthetic CO2-fixation rates, chlorophyll content, chloroplast ultrastructure and other leaf characteristics (e.g. variable fluorescence, stomata density, soluble carbohydrate content) were studied in a comparative way in sun and shade leaves of beech (Fagus sylvatica) and in high-light and low-light seedlings. 1. Sun leaves of the beech possess a smaller leaf area, higher dry weight, lower water content, higher stomata density, higher chlorophyll a/b ratios and are thicker than the shade leaves. Sun leaves on the average contain more chlorophyll in a leaf area unit; the shade leaf exhibits more chlorophyll on a dry weight basis. Sun leaves show higher rates for dark respiration and a higher light saturation of photosynthetic CO2-fixation. Above 2000 lux they are more efficient in photosynthetic quantum conversion than the shade leaves. 2. The development of HL-radish plants proceeds much faster than that of LL-plants. The cotyledons of HL-plants show a higher dry weight, lower water content, a higher ratio of chlorophyll a/b and a higher gross photosynthesis rate than the cotyledons of the LL-plants, which possess a higher chlorophyll content per dry weight basis. The large area of the HL-cotyledon on the one hand, as well as the higher stomata density and the higher respiration rate in the LL-cotyledon on the other hand, are not in agreement with the characteristics of sun and shade leaves respectively. 3. The development, growth and wilting of wheat leaves and the appearance of the following leaves (leaf succession) is much faster at high quanta fluence rates than in weak light. The chlorophyll content is higher in the HL-leaf per unit leaf area and in the LL-leaf per g dry weight. There are no differences in the stomata density and leaf area between the HL- and LL-leaf. There are fewer differences between HL- and LL-leaves than in beech or radish leaves. 4. The chloroplast ultrastructure of shade-type chloroplasts (shade leaves, LL-leaves) is not only characterized by a much higher number of thylakoids per granum and a higher stacking degree of thylakoids, but also by broader grana than in sun-type chloroplasts (sun leaves, HL-leaves). The chloroplasts of sun leaves and of HL-leaves exhibit large starch grains. 5. Shade leaves and LL-leaves exhibit a higher maximum chlorophyll fluorescence and it takes more time for the fluorescence to decline to the steady state than in sun and HL-leaves. The variable fluorescence VF (ratio of fluorescence decrease to steady state fluorescence) is always higher in the sun and HL-leaf of the same physiological stage (maximum chlorophyll content of the leaf) than in the shade and LL-leaf. The fluorescence emission spectra of sun and HL-leaves show a higher proportion of chlorophyli fluorescence in the second emission maximum F2 than shade and LL-leaves. 6. The level of soluble carbohydrates (reducing sugars) is significantly higher in sun and HL-leaves than in shade and LL-leaves and even reflects changes in the amounts of the daily incident light. 7. Some but not all...

Optimizing spectral indices and chemometric analysis of leaf chemical properties using radiative transfer modeling

“…Chlorophylls a and b enable light harvesting for photosynthesis (Anderson, 1986;Lichtenthaler et al, 1981), while carotenoids (carotenes and xanthophylls) and anthocyanins afford protection from excess light, for example during leaf development or abiotic stress (Close and Beadle, 2003;Gould et al, 2008). Measurement of total chlorophyll content (C ab ) and carotenoid content (C xc ) has many applications in agriculture, ecology, and Earth science.…”

Comparison between the structure and function of chloroplasts at different levels of willow canopy during a growing season

“…2B) and the low rates of C0 2 uptake ( Fig. 2A) were possibly caused by altered thylakoid structure typical of shade plants (Lichtenthaler et aL 1981 Part of this reorganization in thylakoid membranes might also be due to ageing, since the area of plastoglobuli of chloroplast area increased (data not shown), which is known to be an indication of ageing (Hudak, 1981). The pattern of thylakoid organization at level 2 (110 cm aboveground) was similar to that at level 1; only the appressed/non-appressed membrane ratio was initially somewhat higher than at level 1.…”

“…There is plenty of evidence that the degree of grana stacking in chloroplasts of plants grown in high light is less than in plants grown in low light (e.g., Lichtenthaler et al, 1981 which is also the case for plants adapted to sunny or shady habitats (Boardman, 1977;Aro et al, 1986 Aro et aL, (1986) and Vapaavuori (1986). On an average, 6 typical chloroplasts were analyzed from each sample of the 3 replicate plots.…”

Light piping driven photosynthesis in the soil: Low-light adapted active photosynthetic apparatus in the under-soil hypocotyl segments of bean (Phaseolus vulgaris)

“…2) but they differed from the typical plastids of leaves. The presence of starch grains and low grana are characteristics of high-light adapted plastids [55,12] while the absence or rare appearance of starch grains, high stacking degree of thylakoids and high grana (16 in average) were found in leaves developed under low-light conditions [56]. The plastids in the US-1 showed diverse features: large starch grains were usually found and the stacking degree was less than 10 thylakoids per grana; these grana were broad.…”