Foliar anthocyanins

Hypotheses for anthocyanin function in leaves are remarkably diverse. Perhaps because foliar anthocyanins can be induced in many circumstances by abiotic stressors such as strong light, temperature extremes, drought, UV-B radiation, mechanical wounding, and nutrient deficiencies, as well as biotic stressors such as herbivory attack and fungal and viral infections, the hypotheses for foliar anthocyanins almost invariably involve phytoprotective functions (Table 7.1). Most research in recent years has focused on three of these hypotheses photoprotection, antioxidant activity, and defense. 

There is no consensus as to the primary function of anthocyanins in leaves. Several authors have attempted unified explanations for foliar anthocyanins these include... 

Table 7.1 Putative phytoprotective roles for foliar anthocyanins.

The photoprotective hypothesis for foliar anthocyanins was no less contentious in Muriel Wheldale s time. Kerner von Marilaum (1885, translated in 1897) was accredited with being one of the first, if not the first, to make suggestions as to the significance... 

The relationship between sucrose, anthocyanins, and stress was explored recently by girdling the branches of sugar maple trees Acer saccharum) in the mid-summer (Murakami et al, 2008). As might be expected from disrupting phloem transport, the treatment led to an accumulation of soluble sugars in the leaves. More surprising, however, was that the treatment also led to simultaneous production of foliar anthocyanins, both... 

Hatier, X-H.B. Gould, K.S. (2008). Foliar anthocyanins as modulators of stress signals. Journal of Theoretical Biology, 253, 625-621. 

---