Boyd Christine N, Franceschi Vincent R, Chuong Simon D X, Akhani Hossein, Kiirats Olavi, Smith Monica, Edwards Gerald E
School of Biological Sciences, Washington State University, Pullman, Washington 99164-4236, USA.
Department of Biology, Faculty of Science, University of Tehran, P.O. Box 14155-6455, Tehran, Iran.
Funct Plant Biol. 2007 May;34(4):268-281. doi: 10.1071/FP06283.
Leaves and cotyledons of the terrestrial C plants, Bienertia cycloptera Bunge ex Boiss. and Suaeda aralocaspica (Bunge) Freitag & Schütze (Chenopodiaceae), accomplish C photosynthesis within individual chlorenchyma cells: each species having a unique means of intracellular spatial partitioning of biochemistry and organelles. In this study the chlorenchyma tissue in flowers and stems of these species was investigated. Flowers have an outer whorl of green tepals with a layer of chlorenchyma cells, which are located on the abaxial side, exposed to the atmosphere. Anatomical, immunocytochemical, western blots and starch analyses show that the chlorenchyma cells in tepals are specialised for performance of single-cell C photosynthesis like that in leaves. In the tepals of B. cycloptera, chlorenchyma cells have a distinctive central cytoplasmic compartment, with chloroplasts which contain Rubisco, separated by cytoplasmic channels from a peripheral chloroplast-containing compartment, with phosphoenolpyruvate carboxylase (PEPC) distributed throughout the cytoplasm. In the tepals of S. aralocaspica, chlorenchyma cells have chloroplasts polarised towards opposite ends of the cells. Rubisco is found in chloroplasts towards the proximal end of the cell and PEPC is found throughout the cytoplasm. Also, green stems of B. cycloptera have a single layer of the specialised C type chlorenchyma cells beneath the epidermis, and in stems of S. aralocaspica, chlorenchyma cells are scattered throughout the cortical tissue with chloroplasts around their periphery, typical of C type chlorenchyma. During reproductive development, green flowers become very conspicuous, and their photosynthesis is suggested to be important in completion of the life cycle of these single-cell C functioning species.
陆生C4植物圆叶节节菜（Bienertia cycloptera Bunge ex Boiss.）和盐穗木（Suaeda aralocaspica (Bunge) Freitag & Schütze）（藜科）的叶片和子叶在单个叶肉细胞内完成C4光合作用：每个物种都有独特的生物化学和细胞器细胞内空间分隔方式。在本研究中，对这些物种花和茎中的叶肉组织进行了研究。花有一轮绿色花被片，其下有一层叶肉细胞，位于远轴面，暴露于大气中。解剖学、免疫细胞化学、蛋白质免疫印迹和淀粉分析表明，花被片中的叶肉细胞专门用于进行单细胞C4光合作用，与叶片中的情况类似。在圆叶节节菜的花被片中，叶肉细胞有一个独特的中央细胞质区室，其中含有核酮糖-1,5-二磷酸羧化酶（Rubisco）的叶绿体通过细胞质通道与外周含叶绿体的区室分隔开，磷酸烯醇式丙酮酸羧化酶（PEPC）分布于整个细胞质中。在盐穗木的花被片中，叶肉细胞的叶绿体朝向细胞的相对两端极化。在细胞近端的叶绿体中发现Rubisco，而PEPC分布于整个细胞质中。此外，圆叶节节菜的绿色茎在表皮下方有单层特化的C4型叶肉细胞，在盐穗木的茎中，叶肉细胞散布于整个皮层组织中，叶绿体围绕其周边，这是C4型叶肉细胞的典型特征。在生殖发育过程中，绿色花朵变得非常显眼，其光合作用对于这些单细胞C4功能物种的生命周期完成可能很重要。
