The Degradation of Chlorophyll — A Biological Enigma

Abstract

Summary Some 109tonnes of chlorophyll are destroyed each year on land and in the oceans. The fate of these chlorophylls is, however, largely unknown. This review describes the developmental stages at which chlorophyll breakdown occurs in aquatic and terrestrial biological systems, and the destruction arising from herbivory, disease, pollution and other physical hazards. At the cellular level, an attempt is made to separate the breakdown of chlorophyll during senescence from the many other events associated with cell destruction and death. A consideration of the more important chemical and biophysical properties of chlorophylls and their derivatives is provided, together with data on their spectral properties. The biosynthetic and biodegradative pathways of chlorophyll metabolism are, so far as is possible, described with some predictions as to the likely fate of the missing tonnes. Two types of degradation are recognized; the first involves up to five defined enzymes concerned with the early stages, the second covers the less well defined enzymic and non‐enzymic destruction of the macrocyclic structure. These degradative reactions are compared with the reactions implicated in the breakdown of other porphyrins including haems in plants and animals. A brief description is given of the occurrence of breakdown products of chlorophyll in past biomass, including those of geological significance and those in a more recent archaeological context. Finally, the economic significance of chlorophyll breakdown is considered in the context of agriculture and horticulture, veterinary and medical sciences, food colouring and cosmetic industries, and the multi‐million‐dollar attraction of autumn leaf fall to tourism.

Chlorophyll and its degradation products in the two-spotted spider mite, Tetranychus urticae: observations using epifluorescence and confocal laser scanning microscopy

“…For instance, silkworm excretes up to four different chlorophyll derivatives, of which two were identified as 13 2 -HO phaeophytin a and b (Nakatani et al 1981). Pigment concentrations from guts of nematodes feeding on microphytobenthic organisms (Majdi et al 2012) and caterpillars feeding on plants (Shao et al 2011) show the presence of chlorophyll and chlorophyll breakdown products (e.g., pheophorbide a and pheophytin a) (Hendry et al 1987). The two-spotted spider mite, a polyphagous species that feeds on more than 1,100 host plants, sucks the plant cell content of leaf mesophyll ( Van der Geest 1985).…”

Update on the biochemistry of chlorophyll breakdown

“…The pioneering identification and structure determination of the first (final) Chl breakdown product, a NCC from barley, named Hv-NCC-1, in 1991 (Kräutler et al 1991) marked a milestone in the elucidation of Chl breakdown, which until then was described as 'biological enigma' (Hendry et al 1987;Brown et al 1991). To date more than 15 structures of NCCs have been identified from over 10 plant species.…”

Lipofuscin-Like Substance Involved in Pericarp Browning of Postharvest Litchi Fruit During Storage

“…It was reported that fruit ripening or senescence was also related to the accumulation of lipofuscin-like substance in pear [4], banana [4,15] and litchi [5]. Hendry, Houghton & Brown [16] proposed the presence of lipofuscin-like substance in living tissue and speculated that lipofuscin-like substance in senescent plant tissue may involve in the breakdown products of chlorophyll originating from methane bridge carbon attached to two halves of pyrroles of macrocyclic ring. Düggelin, Bortlik, Gut, Matile & Thomas [7] observed the different accumulation of lipofuscin-like substance in leaves of Festuca pratensis cv.…”