The fate of chlorophyll in phytophagous insects goes beyond nutrition

Abstract

Chlorophyll (Chl) is a natural compound that is found in all autotrophic plants. Since phytophagous insects ingest the photosynthetically active material with the plant leaves, the question arises if and how herbivores deal with Chl and its degradation products. Here we review findings on Chl degradation in phytophagous insects and highlight the role of these ubiquitous plant metabolites for plant-feeding insects. Due to the anaerobic gut of many insects, the degradation is limited to the removal of the peripheral substituents, while the tetrapyrrole core remains intact. Proteins, such as red fluorescent protein, P252 (a novel 252-kDa protein), and chlorophyllide binding protein have been reported to occur in the insect gut and might be indirectly connected to Chl degradation. Besides of an nutritional value, e.g., by taking up Mg 2+ ions or by sequestration of carbon from the phytol side chain, the Chl degradation products may serve the insect, after binding to certain proteins, as antimicrobial, antifungal, and antiviral factors. The protein complexes may also confer protection against reactive oxygen species. The antibiotic potential of proteins and degradation products does not only benefit phytophagous insects but also human being in medical application of cancer treatment for instance. This review highlights these aspects from a molecular, biochemical, and ecological point of view.

Identification of a Novel Densovirus in Aphid, and Uncovering the Possible Antiviral Process During Its Infection

“…In these pathways, ascorbate and aldarate metabolism has been reported responding to the plant virus infection in M. persicae ( 55 ). Moreover, the degradation products of chlorophyll metabolism would serve antiviral function when binding to their receptor proteins ( 56 ). A recent study shows that the p450 related drug metabolism pathways can regulate the replication of plant virus in insect ( 57 ).…”