Testing the "source-sink" hypothesis of down-regulation of photosynthesis in elevated [CO2] in the field with single gene substitutions in Glycine max
Testing the "source-sink" hypothesis of down-regulation of photosynthesis in elevated [CO2] in the field with single gene substitutions in Glycine max
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DOI：
10.1016/j.agrformet.2003.09.002
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发表时间：
2004-03-20
影响因子：
6.2
通讯作者：
Long, SP
中科院分区：
文献类型：
--
作者：
Ainsworth, EA;Rogers, A;Long, SP
在大豆品系（Glycine max）中进行了光合作用对大气二氧化碳浓度升高的适应试验，这些品系不同的单基因改变了结瘤能力或生长习惯（确定或不确定生长）。在统一的遗传背景下，这两种基因变化都提供了对“源-汇”假说的检验，即在二氧化碳浓度升高的情况下，光合作用的下调是由于无法为额外的光合作用形成足够的“汇”。植物在野外环境和升高[CO2] （550 μ mol mol(-1)）下生长，使用自由空气气体浓度富集（FACE）。将确定品种Elf突变为不确定形式不会导致对升高的[CO2]的响应性增加。这可能反映了在决定品种的选择上有较大的汇容量。在高[CO2]环境下，只有不确定品种（Williams-dtl）的确定等值线和非结瘤基因型的光合作用表现出下调。这是由于体内Rubisco活性（V-c.max）和最大电子传递率的降低造成的。在Williams-dtl中，总非结构性碳水化合物（TNC）含量的增加（通常与光合作用的下调有关）在[CO2]升高的情况下比在[CO2]环境下高出80%，而在不确定系中则为40%。Williams系突变的结果与假设一致，即利用光合作用的遗传能力对于植物在高CO2环境下维持增加光合作用的能力至关重要[C] 2003 Elsevier B.V.。
Acclimation of photosynthesis to elevated atmospheric carbon dioxide concentration was tested in lines of soybean (Glycine max) that differed by single genes that altered either the capacity to nodulate or growth habit (determinate or indeterminate growth). Both genetic changes provided, within a uniform genetic background, a test of the "source-sink" hypothesis that down-regulation of photosynthesis in elevated carbon dioxide is a result of inability to form sufficient "sinks" for the additional photosynthate. Plants were grown under ambient and elevated [CO2] (550 mumol mol(-1)) in the field, using free air gas concentration enrichment (FACE). Mutation of the determinate cultivar, Elf, to an indeterminate form did not result in increased responsiveness to elevated [CO2]. This may reflect a large sink capacity in the selection of determinate cultivars. In elevated [CO2] only the determinate isoline of the indeterminate cultivar (Williams-dtl) and the non-nodulating genotype showed down-regulation of photosynthesis. This resulted from decreases in apparent in vivo Rubisco activity (V-c.max) and maximum rate of electron transport Increase in total non-structural carbohydrate (TNC) content, which is often correlated with down-regulation of photosynthesis, in Williams-dtl was 80% greater in elevated [CO2] than in ambient [CO2] controls, compared to 40% in the indeterminate line. The results from mutations of the Williams line are consistent with the hypothesis that genetic capacity for the utilization of photosynthate is critical to the ability of plants to sustain increased photosynthesis when grown at elevated [CO2] (C) 2003 Elsevier B.V. All rights reserved.