Leaf senescence in Festuca pratensis: accumulation of lipofuscinlike compounds

Fluorescent compounds (FCs) with spectral properties comparable to those of lipofuscin-like compounds are present in aqueous methanolic extracts of senescent meadow fescue, Festuca pratensis Huds., leaves. An HPLC system for the separation of FC from other fluorescent materials was developed. The chromatograms suggest that the FC-fraction consists of a large number of chemically related compounds. FCs are accumulated during senescence in leaves of a yellowing genotype, cv. Rossa. In leaves of a non-yellowing genotype, Bf 993, only traces of FCs appear at advanced stages of senescence.
FCs are regarded as final products of lipid peroxidation. Since both yellowing and non-yellowing genotypes are competent with regard to the degradation of galactolipids (the potential sources of polyunsaturated fatty acids) as well as regarding lipoxygenase (EC 1.13.11.12; a key enzyme of lipid peroxidation), and since incompentence to degrade chlorophyll is associated with lack of FC accumulation in the mutant genotype, it is hypothesized that the polar FCs present in senescent F. pratensis leaves represent catabolites of chlorophyll.