Studies on the Localization and Spectral Characteristics of the Fluorescence Emission of Differently Pigmented Wheat Leaves

Abstract

Intensity, spectral characteristics and localization of the UV‐laser (337 nm) induced blue‐green and red fluorescence emission of green, etiolated and white primary leaves of wheat seedlings were studied in a combined fluorospectral and fluoromicroscopic investigation. The blue‐green fluorescence of the green leaf was characterized by a maximum near 450 nm (blue region) and a shoulder near 530 nm (green region), whereas the red chlorophyll fluorescence exhibited maxima in the near‐red (F690) and far‐red (F735). The etiolated leaf with some carotenoids and traces of chlorophyll a, in turn, showed a higher intensity of the blue‐green fluorescence with a shoulder in the green region and a strong red fluorescence peak near 684 to 690 nm, the far‐red chlorophyll fluorescence maximum (F735) was, however, absent. The norfluorazone‐treated white leaf, free of chlorophylls and carotenoids, only exhibited blue‐green fluorescence of a very high intensity. In green and etiolated leaves the blue‐green fluorescence primarily derived from the cell walls of the epidermis and the red fluorescence from the chlorophyll a of the mesophyll cells. In white leaves the blue‐green fluorescence emanated from all cell walls of epidermis, mesophyll and leaf vein bundles. The shape and intensity of the blue‐green and red fluorescence emission is determined by the reabsorption properties of chlorophylls and carotenoids in the mesophyll, thus giving rise to quite different values of the various fluorescence ratios F450/F690, F450/F530, F450/F735 and F690/F735 in green and etiolated leaves.

Flavonoid Distribution in Tissues of Phillyrea latifolia L. Leaves as Estimated by Microspectrofluorometry and Multispectral Fluorescence Microimaging¶

“…3). Its blue fluorescent spectrum (maximum emission at 475–480 nm) was consistent with the fluorescence properties (36,54,55) of wall‐bound p ‐coumaric, ferulic and caffeic acids (Table 2). Interestingly, sun and shade leaves did not show substantial variations in the concentration of wall‐bound phenylpropanoids, which included flavonoids in addition to hydroxycinnamic acids (Table 2).…”

“…3). For example, the blue fluorescence of wall‐bound p ‐coumaric, ferulic and caffeic acids (54,59,63), which almost exclusively contributed to the fluorescence spectrum of full‐shade leaves (Tables 1 and 2), partly overlapped with the red‐fluorescing glycosides of quercetin and luteolin (Fig. 3).…”

Blue, Green and Red Fluorescence Signatures and Images of Tobacco Leaves*

“…These differences were quantified by forming the fluorescence ratios blue/red, blue/far-red, red/far-red and blue/green. By measuring the fluorescence emission spectra of various leaf parts with and without leaf veins in a conventional fluorometer it was demonstrated that the blue-green fluorescence emission, which is thought to emanate exclusively from the cell walls (Stober and Lichtenthaler, 1993a), is primarily emitted from the main leaf vein and to a lower degree also from the lateral leaf veins. In contrast, the contribution of the intercostal fields to the blue-green fluorescence emission of the leaf was low and seems to primarily derive from the leaf epidermis (confer Stober and Lichtenthaler, 1993a).…”

The total antioxidant capacity and fluorescence imaging of selected plant leaves commonly consumed in Brunei Darussalam

“…Upon UV excitation, both young and matured leaves emit red (R), green (G), and blue (B) fluorescence. These fluorescence characteristics have been normally observed for plant leaves, where the B and G fluorescence with the peak of 450-520 nm might be assigned to ferulic and hydroxycinnamic derivatives bound to the cell wall or mesophyll, and R fluorescence is originated from chlorophylls inside the chloroplast [26][27][28]. Interestingly, as shown in Figs.…”