Changes in pigment accumulation as indicators of physical stress in Eucalyptus pauciflora

Abstract

Investigating whether pigments can be used to reduce the effects of environmental stress and leaf damage is a crucial part of re-evaluating current treatments for herbivory and infection in plants, while also predicting future scenarios with warmer climates. This study investigated whether two pigments (chlorophylls and anthocyanins) could be used as indicators of compromised leaf health in the iconic Australian species Eucalyptus pauciflora Sieber ex Spreng, found in Kosciuszko National Park, NSW, Australia. Additionally, leaf age was also assessed as a contributing factor of leaf damage. Leaf age (represented by leaf area) was associated with increased occurrences of leaf damage in E. pauciflora, with a significant increase in the degree of wounding and pathogen infection observed in older leaves. Chlorophyll content (relative intensity/area) decreased with wounding and infection, supported by suspected damage to photosystems upon physical leaf stress. Anthocyanin content (relative intensity/area) did not change significantly between healthy and damaged leaves, potentially indicating the presence of anthocyanins with different biological functions in E. pauciflora that were not determined by our methods of extraction, but which could be the topic of future studies.