The Effect of Root Hypoxia and Iron Deficiency on the Photosynthesis, Biochemical Composition, and Structure of Pea Chloroplasts

Abstract

The combined effect of root hypoxia and iron deficiency on biochemical composition, photosynthetic indices, and structure of pea (Pisum sativum L.) chloroplasts were investigated. Both factors suppressed chlorophyll accumulation and leaf photosynthetic activity, causing chlorosis. It was shown, that iron deficiency reduced more severe the light-harvesting complexes of photosystems (PS), and root hypoxia, the reaction center complexes of the photosystem I (PSI) and photosystem II (PSII). The combined action of both factors was stronger than the effect of each factor. However, even in yellow and almost white leaves, chloroplasts contained small amounts of all pigment–protein complexes and maintained weak photosynthetic activity, although their structure was poorly developed and comprised only vesicles and small thylakoids capable to form contacts and small grana. The conclusion is that the mechanisms of root hypoxia and iron deficiency destructive action are different and these factors differently and independently influenced leaf chloroplasts.