Decline in photosynthetic electron transport activity and changes in thylakoid protein pattern in field grown iron deficient Peach ( Prunus persica L.)

Abstract

In this work we have studied the influence of lime-induced iron deficiency on some features of the thylakoids from peach trees grown in calcareous soils. Changes in photosynthetic pigments, soluble proteins, photosynthetic activities and thylakoid polypeptides were investigated. The level of total chlorophyll (Chl) and soluble proteins, on a unit fresh weight basis, showed a progressive decrease upon increase in iron deficient condition. When various photosynthetic activities were followed in isolated thylakoids, iron deficiency caused inhibition of whole chain and PS II activity. Smaller inhibition of PS I activity was observed even in severely chlorotic leaves. The artificial exogenous electron donor, Mn 2+ failed to restore PS II activity in both mildly and severely chlorotic leaves, while DPC and NH 2OH significantly restored the PS II activity in severely chlorotic leaves. The same results were obtained when F v/ F m was evaluated by Chl fluorescence measurements. The marked loss of PS II activity in thylakoids isolated from severely chlorotic leaves was due to the loss of D1 protein, 33, 23, 17 kDa extrinsic polypeptides, 28-25 kDa LHCP II polypeptides and 10 kDa polypeptide.