Can anthocyanins be considered as heavy metal stress indicator in higher plants?

The observed influence of some environmental stresses on the level of anthocyanins in higher plants raised the question whether these common flavonoids can be heavy metal stress indicators. The experiments on the effect of cadmium, nickel, lead and zinc on the content of anthocyanins in the first leaves of rye seedlings have clearly shown that it was not directly related to the individual metal toxicity, i.e. the more toxic is the metal the less anthocyanins is accumulated. Instead of anthocyanin test, the determination of the level of chlorophyll and total carotenoids is postulated as a simple and reliable indicator of heavy metal toxicity for higher plants.