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首页> 美国卫生研究院文献>Plant Physiology >Spatial and Temporal Distribution of Polyamine Levels and Polyamine Anabolism in Different Organs/Tissues of the Tobacco Plant. Correlations with Age Cell Division/Expansion and Differentiation
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Spatial and Temporal Distribution of Polyamine Levels and Polyamine Anabolism in Different Organs/Tissues of the Tobacco Plant. Correlations with Age Cell Division/Expansion and Differentiation

机译：烟草植物不同器官/组织中多胺水平和多胺代谢的时空分布。与年龄细胞分裂/扩增和分化的相关性

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Polyamine (PA) titers and biosynthesis follow a basipetal decrease along the tobacco (Nicotiana tabacum) plant axis, and they also correlate negatively with cell size. On the contrary, the titers of arginine (Arg), ornithine (Orn), and arginase activity increase with age. The free (soluble)/total-PA ratios gradually increase basipetally, but the soluble conjugated decrease, with spermidine (Spd) mainly to determine these changes. The shoot apical meristems are the main site of Spd and spermine biosynthesis, and the hypogeous tissues synthesize mostly putrescine (Put). High and low Spd syntheses are correlated with cell division and expansion, respectively. Put biosynthetic pathways are differently regulated in hyper- and hypogeous tobacco tissues: Only Arg decarboxylase is responsible for Put synthesis in old hypergeous vascular tissues, whereas, in hypogeous tissues, arginase-catalyzed Orn produces Put via Orn decarboxylase. Furthermore, Orn decarboxylase expression coincides with early cell divisions in marginal sectors of the lamina, and Spd synthase strongly correlates with later cell divisions in the vascular regions. This detailed spatial and temporal profile of the free, soluble-conjugated, and insoluble-conjugated fractions of Put, Spd, and spermine in nearly all tobacco plant organs and the profile of enzymes of PA biosynthesis at the transcript, protein, and specific activity levels, along with the endogenous concentrations of the precursor amino acids Arg and Orn, offer new insight for further understanding the physiological role(s) of PAs. The results are discussed in the light of age dependence, cell division/expansion, differentiation, phytohormone gradients, senescence, and sink-source relationships.
机译：多胺（PA）的滴度和生物合成沿烟草（Nicotiana tabacum）植物轴的基底基底减少，并且它们与细胞大小呈负相关。相反，精氨酸（Arg），鸟氨酸（Orn）和精氨酸酶活性的滴度会随着年龄的增长而增加。游离（可溶）/总PA的比值逐渐升高，但可溶共轭物的含量降低，其中亚精胺（Spd）主要决定这些变化。茎尖分生组织是Spd和精胺生物合成的主要部位，而次生组织主要合成腐胺（Put）。高和低Spd合成分别与细胞分裂和扩增相关。在高糖和低糖烟草组织中，put生物合成途径受到不同的调节：只有Arg脱羧酶负责旧的高糖血管组织中的Put合成，而在低糖组织中，精氨酸酶催化的Orn通过Orn脱羧酶产生Put。此外，Orn脱羧酶表达与叶片边缘区的早期细胞分裂相符，而Spd合酶与血管区域中的后期细胞分裂密切相关。几乎所有烟草植物器官中Put，Spd和spermine的游离，可溶结合和不可溶结合部分的详细时空分布以及在转录本，蛋白质和比活度水平上PA生物合成酶的分布，以及前体氨基酸Arg和Orn的内源性浓度，为进一步了解PA的生理作用提供了新的见识。根据年龄依赖性，细胞分裂/扩展，分化，植物激素梯度，衰老和库源关系对结果进行了讨论。

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