Welsh Plant Breeding Station, Plas Gogerddan, SY23 3EB, Aberystwyth, UK.
Planta. 1977 Jan;137(1):53-60. doi: 10.1007/BF00394435.
A study was made of the structure and function of senescent chloroplasts from a non-yellowing (NY) mutant of Festuca pratensis. Electron microscopy suggested that the stroma matrix was destroyed but that thylakoid membranes persisted in a loose, unstacked condition. By contrast, chloroplasts from the normal (Y) genotype lost both stroma and recognizable thylakoid systems. Fraction 1, the major protein of the stroma, disappeared from Y and NY at similar rates during senescence. The activities of photosystems I and II from NY also declined at a similar rate to Y photosystems. Polypeptides of chloroplast membranes were separated by SDS gel electrophoresis into at least 30 components. There was considerable heterogeneity in rates of breakdown of the different protein species of the membranes. Of the five major polypeptide components, two had kinetics of breakdown similar to those of stroma proteins and were lost from NY and Y at about the same rate, whereas the remaining three (one of which was tentatively identified as the apoprotein of the light-harvesting chlorophyll-protein complex) were more stable in NY than in Y. These results are discussed in relation to the mechanism and function of chloroplast disintegration during leaf senescence.
对羊茅非黄化（NY）突变体衰老叶绿体的结构和功能进行了研究。电子显微镜观察表明，基质基质被破坏，但类囊体膜仍处于松散、未堆叠的状态。相比之下，来自正常（Y）基因型的叶绿体既失去了基质又失去了可识别的类囊体系统。在衰老过程中，第 1 馏分，基质的主要蛋白质，在 Y 和 NY 中以相似的速度消失。NY 的光系统 I 和 II 的活性也以与 Y 光系统相似的速率下降。用 SDS 凝胶电泳将叶绿体膜的多肽分离成至少 30 个成分。不同膜蛋白种类的降解速率存在很大的异质性。在五个主要的多肽成分中，有两个的降解动力学与基质蛋白相似，从 NY 和 Y 中以相似的速度丢失，而其余三个（其中一个被暂时鉴定为光捕获叶绿素蛋白复合物的脱辅基蛋白）在 NY 中比在 Y 中更稳定。这些结果与叶片衰老过程中叶绿体解体的机制和功能有关。
