Ladygin V G, Semenova G A
Institute of Basic Biological Problems RAS, Pushchino, Moscow Region.
Tsitologiia. 2003;45(8):780-95.
A combined effect of iron deficiency and root hypoxia on the biochemical composition activity and structure of chloroplasts in pea leaves have been studied. Both factors are shown to affect the accumulation of chlorophyll causing leaf chlorosis. At iron deficiency chlorosis occurs from the top of plant leaves. At root hypoxia chlorosis starts from the lower strata. At a combined action of both factors the destructive effects are summarized. It was established that light-harvesting complexes of photosystems were reduced stronger at iron deficiency, while complexes of reaction centers of photosystem I and photosystem II are lessened at root hypoxia. Nevertheless, even at a combined effect of both factors yellow leaves preserved small amounts of any pigment-protein complexes and their functional activities. The ultrastructure of chloroplasts during leaf chlorosis was gradually reduced. At first, intergranal sites of thylakoids and then granal ones were destroyed, that was typical of iron deficiency. However, even yellow and almost white leaves kept small thylakoids, capable of forming stacking and small grana made of 2-3 thylakoids. It has been concluded that the destructive effects are summarized due to different kinds of action of iron deficiency and root hypoxia on the structure and functioning of leaves at their combined action.
研究了缺铁和根系缺氧对豌豆叶片叶绿体生化组成、活性及结构的综合影响。结果表明，这两个因素均会影响叶绿素的积累，导致叶片黄化。缺铁时，黄化从植株顶部叶片开始；根系缺氧时，黄化从下部叶片开始。当两个因素共同作用时，破坏作用会叠加。研究发现，缺铁时光系统的捕光复合体减少更明显，而根系缺氧时光系统Ⅰ和光系统Ⅱ的反应中心复合体减少。然而，即使在两个因素共同作用下，黄叶仍保留少量的任何色素 - 蛋白质复合体及其功能活性。叶片黄化过程中叶绿体的超微结构逐渐受损。起初，类囊体的间质部位被破坏，随后基粒部位被破坏，这是缺铁的典型特征。然而，即使是黄色甚至几乎白色的叶片仍保留着能够形成堆叠的小类囊体以及由2 - 3个类囊体组成的小基粒。研究得出结论，在缺铁和根系缺氧共同作用时，由于它们对叶片结构和功能的不同作用方式，破坏作用会叠加。
