Evolution of C4 Photosynthesis in the Genus Flaveria: Establishment of a Photorespiratory CO2 Pump[W]
Evolution of C4 Photosynthesis in the Genus Flaveria: Establishment of a Photorespiratory CO2 Pump[W]
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DOI：
10.1105/tpc.113.114520
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发表时间：
2013-07
期刊：
影响因子：
11.6
通讯作者：
Stefanie Schulze;Julia Mallmann;Janet Burscheidt;Maria Koczor;M. Streubel;H. Bauwe;U. Gowik;P. Westhoff
中科院分区：
文献类型：
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作者：
Stefanie Schulze;Julia Mallmann;Janet Burscheidt;Maria Koczor;M. Streubel;H. Bauwe;U. Gowik;P. Westhoff
光呼吸CO2泵的建立被认为是C4光合作用进化的早期和重要步骤。这篇文章提供了实验证据表明，该泵的建立在属Flaveria的Gly脱羧酶P-蛋白基因的差异表达促进。C4光合作用是自然界对核酮糖-1，5-二磷酸羧化酶/加氧酶的双重活性和通过光呼吸导致的CO2损失的最有效的回答。甘氨酸脱羧酶（Gly decarboxylase，GDC）是植物光呼吸CO2释放的关键组分，在C3植物的所有光合组织中都有活性，但仅在C4植物的维管束鞘细胞中有活性。GDC对维管束鞘的限制被认为是C4光合作用进化的重要和早期步骤，导致光呼吸CO2浓缩机制。在这项研究中，我们分析了如何GDC的P-蛋白（GLDP）成为限制在维管束鞘中的C3到C4光合作用的过渡在黄属植物。我们发现，C3黄菊物种已经包含一个维管束鞘表达的GLDP基因，除了一个普遍表达的第二个基因，这成为一个假基因在C4黄菊物种。对C3-C4中间黄曲霉属物种的分析表明，光呼吸CO2泵不是一步建立的，而是逐渐建立的。这项研究所获得的知识揭示了C4进化的早期步骤。
The establishment of the photorespiratory CO2 pump is thought to be an early and essential step in the evolution of C4 photosynthesis. This article provides experimental evidence that the establishment of this pump in the genus Flaveria was facilitated by the differential expression of Gly decarboxylase P-protein genes. C4 photosynthesis is nature’s most efficient answer to the dual activity of ribulose-1,5-bisphosphate carboxylase/oxygenase and the resulting loss of CO2 by photorespiration. Gly decarboxylase (GDC) is the key component of photorespiratory CO2 release in plants and is active in all photosynthetic tissues of C3 plants, but only in the bundle sheath cells of C4 plants. The restriction of GDC to the bundle sheath is assumed to be an essential and early step in the evolution of C4 photosynthesis, leading to a photorespiratory CO2 concentrating mechanism. In this study, we analyzed how the P-protein of GDC (GLDP) became restricted to the bundle sheath during the transition from C3 to C4 photosynthesis in the genus Flaveria. We found that C3 Flaveria species already contain a bundle sheath–expressed GLDP gene in addition to a ubiquitously expressed second gene, which became a pseudogene in C4 Flaveria species. Analyses of C3-C4 intermediate Flaveria species revealed that the photorespiratory CO2 pump was not established in one single step, but gradually. The knowledge gained by this study sheds light on the early steps in C4 evolution.