Post-illumination CO2 exchange and light-induced CO2 bursts during C-4 photosynthesis
Post-illumination CO2 exchange and light-induced CO2 bursts during C-4 photosynthesis
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DOI：
10.1071/pp97002
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发表时间：
1997-01-01
期刊：
影响因子：
--
通讯作者：
Edwards, GE
中科院分区：
文献类型：
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作者：
Laisk, A;Edwards, GE
使用完全响应时间为 3.5 s 的气体系统，在高粱（一种 NADP-苹果酸酶 (NADP-ME)）和苋菜（一种 NAD-苹果酸酶 (NAD-ME) 型 C-4 植物）的叶子中测量了光照后 CO2 交换的详细动力学以及光照交换后的暗光瞬变。黑暗中固定的CO2量（同化电荷，AC）对于A. cruentus可达200 mu mol m(-2)，对于S. bicolor可达350-450 mu mol m(-2)。当 CO2 浓度接近 CO2 响应曲线的拐点时，AC 达到最大值，当光合作用受到低光强度限制时，AC 会降低。光照后 CO2 固定的动力学表明，C-4 循环中的羧化速率受到磷酸烯醇丙酮酸供应的限制。在 A. cruentus 中，在饱和 CO2 下，光照后 CO2 吸收被爆发 (68 mu mol m(-2)) 所取代。在 S. bicolor 中，暗光诱导开始于 415 mu mol m(-2) 的快速 CO2 爆发（不到 5 秒），然后是一口吞下。观察到的 CO2 瞬变显示 C-4 和 C-3 循环不平衡。在 S. bicolor 中，缺乏光照后爆发以及光诱导 CO2 爆发的存在被视为 NADP-ME 物种中苹果酸脱羧与 PGA 还原严格耦合的证据； A. cruentus 中的相反反应表明 NAD-ME 物种中 C-4 和 C-3 循环之间缺乏严格的耦合。
Detailed kinetics of the post-illumination CO2 exchange, and dark-light transients following post-illumination exchange, were Measured in leaves of Sorghum bicolor, a NADP-malic enzyme (NADP-ME), and Amaranthus cruentus, a NAD-malic enzyme (NAD-ME) type C-4 plant using a gas system that has a full-response time of 3.5 s. The amount of CO2 fixed in the dark (assimilatory charge, AC) was up to 200 mu mol m(-2) for A. cruentus and 350-450 mu mol m(-2) for S. bicolor. AC was at its maximum value at CO2 concentrations close to the inflection of the CO2 response curve, and decreased when photosynthesis was limited by low light intensity. The kinetics of post-illumination CO2 fixation indicate that the rate of carboxylation in the C-4 cycle is limited by the supply of phosphoenolpyruvate. In A. cruentus, under saturating CO2 the post-illumination CO2 uptake was replaced by a burst (68 mu mol m(-2)). In S. bicolor, the dark-light induction commenced with a rapid CO2 burst (less than 5 s) of 415 mu mol m(-2), followed by a gulp. The observed CO2 transients show imbalances in the C-4 and C-3 cycles. In S. bicolor the lack of a post-illumination burst, and the presence of the light-induced CO2 burst is taken as evidence for strict coupling of malate decarboxylation to PGA reduction in NADP-ME species; the opposite response in A. cruentus indicates the lack of strict coupling between the C-4 and C-3 cycle in NAD-ME species.