ABSTRACT
Pollen from the second species has more intensive maximum in blue at 455460 nm and in yellow at 530 nm, than in the anther, while in the first species there is no difference between pollen grain and anther* Light emission excited by UV-light represents the overall luminescence of a multicomponent system (van Gijzel, 1971; Roshchina et al., 1996; 1997b). It includes: (1) the surface luminescence of sporopollenin, exine, including such fluorescing components as phenols, carotenoids, azulenes, pyridine nucleotides, flavins and others; (2) the luminescence of the components of the intine — the membrane present under sporopollenin (they may be represented, in the main, by pectin compounds); and (3) the luminescence of the components of the cytoplasm and organelles. The main role in the global fluorescence spectrum is probably played by the sporopollenin components, since their removal leads to a considerable reduction in fluorescence in the blue region (see Chapter 1, Section 1.3, Fig. 1.7). Willemse (1971) considers that the contribution to the total luminescence of the components of the intine, the cell wall and cytoplasm with organelles is low compared with the potent fluorescence of sporopollenin itself. In addition, it should be borne in mind that ultraviolet light exciting fluorescence penetrates with difficulty into the pollen grain through sporopollenin. Sporopollenin consists of polymers of terpenoids (carotenoids) or/and phenols. The rapid changes occurring in sporopollenin lead to appreciable shifts in the fluorescence spectra during
