Control of carbon partitioning and photosynthesis by the triose phosphate/phosphate translocator in transgenic tobacco plants (Nicotiana tabacum). II. Assessment of control coefficients of the triose phosphate/phosphate translocator
Control of carbon partitioning and photosynthesis by the triose phosphate/phosphate translocator in transgenic tobacco plants (Nicotiana tabacum). II. Assessment of control coefficients of the triose phosphate/phosphate translocator
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DOI：
10.1007/pl00008146
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发表时间：
2000-02
期刊：
影响因子：
4.3
通讯作者：
R. Häusler;Nils Helge Schlieben;U. Flügge
中科院分区：
文献类型：
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作者：
R. Häusler;Nils Helge Schlieben;U. Flügge
对转基因烟草的生理特性进行了研究。比较了叶绿体磷酸三糖/磷酸转运体(TPT)在叶绿体转运能力降低或增加的情况下，TPT对野生型烟草代谢通量的控制程度。为此，利用内源TpT反义抑制烟草株系(FtTpt)和从C4植物黄萎病菌中分离的高表达TpT基因的烟草株系(αTpt)进行了研究。小偷。在酵母细胞中表达的trineviaTPT具有与C3植物中的TPT相同的运输特性。无论是反义TPT植株还是FtTPT过表达植株，在温室空气中生长时都没有表现出表型。光周期结束时，TPT低表达和FtTPT高表达的上部源叶淀粉和可溶性糖含量与野生型相近。与野生型相比，FtTPT高表达基因在蔗糖中掺入了更多的14CO2，表明TPT限制了野生型的蔗糖生物合成。对氨基酸和有机酸的标记影响很小。与野生型相比，FtTPT高表达株系的淀粉动员增强，而α高表达株的淀粉动员能力降低。参与淀粉动员或利用的酶，如α-淀粉酶或己糖激酶，在αTPT植物中增加，而在淀粉酶的情况下，FtTPT过表达的酶减少。此外，α-淀粉酶活性在αTPT品系中表现出明显的日变化，在光照8 h后活性最高。天然凝胶活性染色证实了淀粉水解酶活性的这些变化。葡聚糖磷酸化酶的活性不受TPT活性降低或增加的影响。TPT活性对磷酸化中间体以及总氨基酸和苹果酸的稳态水平也有影响。在空气中，TPT运输活性的改变对光合作用电子传递和/或CO2同化速率都没有或几乎没有影响。但在高CO2(15 0 0 μL · L−1)和低O2(2%)条件下，αTPT品系的CO2同化率降低，而FtTPT品系的CO2同化率略高。这表明TPT限制了野生型的最大光合作用速率。
The physiological properties of transgenic tobacco plants (Nicotiana tabacumL.) with decreased or increased transport capacities of the chloroplast triose phosphate/phosphate translocator (TPT) were compared in order to investigate the extent to which the TPT controls metabolic fluxes in wild-type tobacco. For this purpose, tobacco lines with an antisense repression of the endogenous TPT (αTPT) and tobacco lines overexpressing the TPT gene isolated from the C4plantFlaveria trinervia(FtTPT) were used. TheF. trinerviaTPT expressed in yeast cells exhibited transport characteristics identical to the TPT from C3plants. Neither antisense TPT plants nor FtTPT overexpressors showed a phenotype when grown in a greenhouse in air. Contents of starch and soluble sugars in upper source leaves were similar in TPT underexpressors and FtTPT overexpressors compared to the wild type at the end of the photoperiod. The FtTPT overexpressors incorporated more14CO2in sucrose than the wild type, indicating that the TPT limits sucrose biosynthesis in the wild type. There were only small effects on labelling of amino acids and organic acids. The mobilisation of starch was enhanced in αTPT lines but decreased in FtTPT overexpressors compared to the wild type. Enzymes involved in starch mobilisation or utilisation, such as α-amylase or hexokinase were increased in αTPT plants and, in the case of amylases, decreased in FtTPT overexpressors. Moreover, α-amylase activity exhibited a pronounced diurnal variation in αTPT lines with a maximum activity after 8 h in the light. These changes in starch hydrolytic activities were confirmed by activity staining of native gels. Activities of glucan phosphorylases were unaffected by either a decrease or an increase in TPT activity. There were also effects of TPT activities on steady-state levels of phosphorylated intermediates as well as total amino acids and malate. In air, there was no or little effect of altered TPT transport activity on either rates of photosynthetic electron transport and/or CO2assimilation. However, in elevated CO2(1500 μl · l−1) and low O2(2%) the rate of CO2assimilation was decreased in the αTPT lines and was slightly higher in FtTPT lines. This shows that the TPT limits maximum rates of photosynthesis in the wild type.