Iron deficiency induced changes on the donor side of PS II in field grown grapevine (Vitis vinifera L. cv. Pinot noir) leaves

In this work we have studied the influence of lime-induced iron deficiency on some features of the thylakoids and PS II membranes from grapevine ( Vitis vinifera L. cv. Pinot noir) plants grown in calcareous soils. Changes in photosynthetic activities and PS It membrane polypeptides were investigated. When various photosynthetic electron transport activities were analyzed in isolated thylakoids, a major decrease in the rate of whole chain (H2O --> MV) electron transport was observed in chlorotic leaves, Such reduction was mainly due to the loss of PS II activity. Smaller inhibition of PS I activity was also observed in chlorotic leaves. The artificial electron donors, DPC and NH2OH markedly restored the loss of PS II activity in chlorotic leaves. The same results were obtained when variable fluorescence/maximum fluorescence (Fv/Fm) was evaluated by chlorophyll (Chl) fluorescence measurements. The marked loss of PS II activity in chlorotic leaves was evidently due to the loss of D1, 33, 28-25, and 23 kDa polypeptides. This conclusion was confirmed by immunological studies showing that the content of the D1 protein of the PS II reaction centre and of the 33 kDa protein of the water-splitting complex was diminished significantly in chlorotic leaves. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.