Studies on the regulatory mechanisms of growth of cultured plant cells and organelles

我们的研究目标是利用培养的植物细胞来了解细胞生长、分化和细胞器发育的调控机制。我们从细胞和细胞器水平分析了烟草细胞生长过程中的核酸和蛋白质合成、光合作用和呼吸活性。此外，我们还分析了烟草中一种膜结合的生长素结合蛋白，该蛋白被认为在细胞生长和分化中介导了生长素的作用。研究结果总结如下：1)2，4-D持续的光营养品系在光下生长期间产生了光合作用。光合作用活性的发展与几种叶绿体蛋白的合成有关，包括Rubisco的一个小亚基，以及光系统II活性的发展；2)异养生长的烟草细胞在细胞和线粒体水平上都表现出与生长周期相关的呼吸活性变化。The ch…呼吸活性的更多变化主要通过细胞色素途径发生，而抗氰化物替代途径的活性在整个生长周期中保持不变。外源供应的糖的种类和数量不影响替代途径的相对贡献。我们的结果表明，呼吸作用受到腺苷类化合物的强烈控制，这表明替代途径发挥了作用，而不是能量溢出。3)从烟草悬浮细胞培养物中溶解并鉴定了膜结合生长素结合蛋白(MABP)。结果表明，MABP是一类不同于胞质可溶性的生长素结合蛋白。利用一个生长素抗性突变体和一个根癌农杆菌转化子，MABP被证明受到细胞分裂素的调控，并参与生长素介导的根分化。MABP在根分化的器官(根)培养体系中的作用也被证明。较少

Our research objectives were to understand the regulatory mechanisms of cell growth, differentiation and organellar development using cultured plant cells. We analyzed nucleic acid and protein syntheses, photosynthesis and respiratory activity during growth of tobacco cells at both the cellular and organellar levels. In addition, we analyzed a membrane-bound auxin-binding protein in tobacco which was thought to mediate auxin action in cell growth and differentiation.The results obtained are summarized as follows, i) photosynthetic activity developed in a 2,4-D-sustained photomixotrophic line of tobacco during growth in the light. The development of photosynthetic activity correlated with the synthesis of several chloroplast proteins including a small subunit of Rubisco and with the developwent of photosystem II activity; 2) heterotrophically grown tobacco cells showed growth cycle-related changes in the respiratory activity measured both at the cellular and mitochondrial levels. The ch … More anges in the respiratory activity occurred mainly through the cytochrome pathway, while the activity of the cyanide-resistant alternative pathway remained constant throughout the growth cycle. Kinds and amounts of sugars exogenously supplied did not affect the relative contribution of the alternative pathway. Our results show that the respiration is under strong control by adenylates and suggest that the alternative pathway plays a role other than an energy overflow; 3) a membrane-bound auxin-binding protein (MABP) was solubilized from cell suspension cultures of tobacco and characterized. The results show that MABP is a class of auxin-binding protein distinct from a cytosolic soluble type. Using an auxin-resistant variant and a transformant by agrobacterium tumefaciens, MABP was shown to be regulated by cytokinin and involved in auxin-mediated root differentiation. A role of MABP in root differentiation was also shown using an organ (root) culture system in which root differentiation could be manipulated. Less