Analysis of the feed-forward effects of sink activity on the photosynthetic source-sink balance in single-rooted sweet potato leaves. I. Activation of RuBPcase through the development of sinks.
Analysis of the feed-forward effects of sink activity on the photosynthetic source-sink balance in single-rooted sweet potato leaves. I. Activation of RuBPcase through the development of sinks.
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DOI：
10.1093/pcp/pcg024
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发表时间：
2003-02
影响因子：
4.9
通讯作者：
S. Sawada;Makiko Sato;Akihito Kasai;Daisuke Yaochi;Youjiro Kameya;Izumi Matsumoto;M. Kasai
中科院分区：
文献类型：
--
作者：
S. Sawada;Makiko Sato;Akihito Kasai;Daisuke Yaochi;Youjiro Kameya;Izumi Matsumoto;M. Kasai
在50 d的实验期内，单根甘薯叶片（叶柄带有茎段）向唯一的主要储存器官——块茎根分配了异常大量的光合产物。固定CO(2)的光合活性的增加完全依赖于块根生长带来的碳汇活性的发展。因此，该模型对光合源汇平衡表现出显著的前馈效应。在此期间，叶片中核酮糖-1,5-二磷酸羧化酶（RuBPcase）蛋白水平持续升高。在实验开始时观察到的RuBPcase的初始活性和总活性降低，由于块根的发育，随着汇限制状态的取消而提高。用SO(4)（2-）处理叶提取物去除部分酶抑制剂后测定的最大活性远远大于总活性，并且在整个实验期间基本保持不变。随着块根的发育，最大活性和总活性之间的差异明显减小，这可能反映了RuBPcase通过取消库限制状态从酶中去除一些抑制剂而重新激活。
Single-rooted sweet potato leaves having a petiole with a fragment of stem allocated exceptionally large amounts of photosynthates to tuberous roots, the only major storage organ, throughout an experimental period of 50 d. The increase in photosynthetic activity for CO(2) fixation depended exclusively on the development of sink activity due to the growth of tuberous roots. Thus this model expressed a remarkable feed-forward effect on the photosynthetic source-sink balance. The level of ribulose-1,5-bisphosphate carboxylase (RuBPcase) protein in the leaves increased continuously during the period. The lowered initial as well as total activity of RuBPcase observed at the start of the experiment was raised with the cancellation of the sink-limited state due to the development of tuberous roots. The maximum activity determined after removing some inhibitor(s) from the enzyme by treating the leaf extract with SO(4)(2-) was much greater than the total activity and remained approximately constant throughout the experimental period. The clear decrease in the difference between maximum and total activities with the development of tuberous roots might reflect the reactivation of RuBPcase due to the removal of some inhibitor(s) from the enzyme through the cancellation of the sink-limited state.