The lutein epoxide cycle in vegetative buds of woody plants

Recent works have shown that two xanthophyll cycles operate simultaneously in several plant species: the ubiquitous violaxanthin + anteraxanthin + zeaxanthin (VAZ) cycle and the lutein epoxide (Lx) cycle. In the present work we tested for the presence of the Lx cycle in vegetative buds of woody plants. After an extensive screening of 130 species, we have shown that Lx is present in buds of many different plant species and leaf primordia are enriched in Lx compared with leaves. As a result, the Lx pool was higher than the violaxanthin (V) pool in several species. Although Lx can be potentially de-epoxidised in buds, light attenuation by scales inhibited the daily operation of the Lx cycle. This finding would imply that the Lx cycle is not involved in short-term reversible photoprotection in buds. However, a light-induced decrease in Lx was observed through the winter. An extensive screening of 130 species in 49 families conducted to elucidate the taxonomic extension of this cycle showed a widespread presence of the Lx cycle. The presence of Lx has a high fidelity at the family level, but its presence in unrelated taxa suggests that this character has appeared independently in several different groups of plants.