Antisense-inhibition of ADP-glucose pyrophosphorylase in Vicia narbonensis seeds increases soluble sugars and leads to higher water and nitrogen uptake
Antisense-inhibition of ADP-glucose pyrophosphorylase in Vicia narbonensis seeds increases soluble sugars and leads to higher water and nitrogen uptake
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DOI：
10.1007/s00425-001-0710-4
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发表时间：
2002-04
期刊：
影响因子：
4.3
通讯作者：
H. Rolletschek;M. Hajirezaei;U. Wobus;H. Weber
中科院分区：
文献类型：
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作者：
H. Rolletschek;M. Hajirezaei;U. Wobus;H. Weber
我们以前报道过由于反义抑制而使α-D-葡萄糖-1-磷酸腺苷转移酶（AGP; EC 2.7.7.27）显著降低的野豌豆种子[H. Weber等人（2000）Plant J 24：33-43]。在一个扩展的生化分析中，我们在这里表明，在转基因种子的AGP活性和ADP-葡萄糖水平都强烈下降，但淀粉只有适度减少，含有较少的直链淀粉。AGP对淀粉积累的流量控制系数很低，仅为0.08，说明AGP对豌豆淀粉合成的控制作用较弱。反义种子成熟子叶中脂类、氮、硫含量增加。蛋白质含量更高，特别是由于富含硫的白蛋白增加。贮藏蛋白的球蛋白组分具有较低的豆球蛋白与豌豆球蛋白的比率。离体子叶分配较少的[14 C]蔗糖转化为淀粉，更多的转化为可溶性糖，蛋白质组分没有变化。离体子叶的呼吸和主要的糖酵解和碳水化合物代谢酶的活性没有受到影响。蔗糖和己糖-磷酸池增加，但UDP-葡萄糖，3-磷酸甘油酸，磷酸烯醇丙酮酸，丙酮酸，ATP和ADP不变或甚至更低，表明碳分配从淀粉改变为蔗糖，而不影响糖酵解和呼吸途径。可溶性化合物增加，但渗透压保持不变，表明补偿性水流入导致更高的水含量。发育模式的水和氮的积累表明耦合吸收的氨基酸和水分进入子叶。我们的结论是，由于更高的水分吸收，转基因子叶采取更多的氨基酸，成为可用于蛋白质生物合成，导致更高的蛋白质含量。显然，蚕豆对氨基酸的吸收很大一部分是被动发生的，并受水分流入的控制和驱动。
We previously reported onVicia narbonensisseeds with largely decreased α-D-glucose-1-phosphate adenyltransferase (AGP; EC 2.7.7.27) due to antisense inhibition [H. Weber et al. (2000) Plant J 24:33–43]. In an extended biochemical analysis we show here that in transgenic seeds both AGP activity and ADP-glucose levels were strongly decreased but starch was only moderately reduced and contained less amylose. The flux control coefficient of AGP to starch accumulation was as low as 0.08, i.e. AGP exerts low control on starch biosynthesis inViciaseeds. Mature cotyledons of antisense seeds had increased contents of lipids, nitrogen and sulfur. The protein content was higher due, in particular, to increased sulfur-rich albumins. Globulin fractions of storage proteins had a lower ratio of legumin to vicilin. Isolated cotyledons partitioned less [14C]sucrose into starch and more into soluble sugars with no change in the protein fraction. Respiration of isolated cotyledons and activities of the major glycolytic and carbohydrate-metabolizing enzymes were not affected. Sucrose and the hexose-phosphate pool were increased but UDP-glucose, 3-phosphoglyceric acid, phosphoenolpyruvate, pyruvate, ATP and ADP were unchanged or even lower, indicating that carbon partitioning changed from starch to sucrose without affecting the glycolytic and respiratory pathways. Soluble compounds were increased but osmolality remained unchanged, indicating compensatory water influx resulting in higher water contents. Developmental patterns of water and nitrogen accumulation suggest a coupled uptake of amino acids and water into cotyledons. We conclude that, due to higher water uptake, transgenic cotyledons take up more amino acids, which become available for protein biosynthesis leading to a higher protein content. Obviously, a substantial part of amino acid uptake intoViciaseeds occurs passively and is osmotically controlled and driven by water influx.