Zeatin modulates flower bud development and tocopherol levels in Cistus albidus (L.) plants as they age

In a previous study we showed that Cistus albidus (L.) experiences an age‐dependent decay in flower vigour correlated with a decline in trans ‐zeatin (t Z ) levels. In the present study we aimed to establish a causal relationship between these two phenomena. Exogenous t Z applied to plants grown under semi‐controlled conditions did not rescue flower vigour; however, it accelerated flower development, but only in younger individuals. Older plants showed lower tocopherol levels in flower buds, which were restored by exogenous t Z , suggesting that a loss of antioxidant defences may underlie the age‐dependent decay in flower vigour. We conclude that declining t Z levels may not be directly responsible for the age‐associated loss of floral vigour; that t Z modulates the speed of flower development as plants age; and that flower buds alter their sensitivity to t Z as plants age.