Towards an integrative model of C4 photosynthetic subtypes: insights from comparative transcriptome analysis of NAD-ME, NADP-ME, and PEP-CK C4 species
Towards an integrative model of C4 photosynthetic subtypes: insights from comparative transcriptome analysis of NAD-ME, NADP-ME, and PEP-CK C4 species
复制标题
DOI：
10.1093/jxb/eru100
复制
发表时间：
2014-07-01
影响因子：
6.9
通讯作者：
Weber, Andreas P. M.
中科院分区：
文献类型：
--
作者：
Braeutigam, Andrea;Schliesky, Simon;Weber, Andreas P. M.
C-4光合作用提供比C-3光合作用更高的光合碳转化效率，因此它代表了旨在提高作物生产力的工程努力的有吸引力的目标。为此，需要尽可能接近地反映C-4代谢的蓝图。这些蓝图来自于C-3物种与相关C-4物种的比较转录组分析，这些物种属于C-4光合作用的NAD-苹果酸酶（NAD-ME）和NADP-ME亚组。然而，C-3和C-4光合作用的磷酸烯醇丙酮酸羧激酶（PEP-CK）亚型之间的比较仍然缺失。迄今为止，对所有三种C-4亚型进行综合分析也是不可能的，因为没有对密切相关的C-3和PEP-CK C-4物种进行比较。为了生成数据，将代表PEP-CK物种的几内亚草Megathyrsus maximus与密切相关的C-3姐妹物种Dichanthalus clandestinum以及来自属于NAD-ME和NADP-ME亚组的C-4物种的公开可用的RNA-Seq数据集进行比较。结果表明，PEP-CK草地早熟禾的核心C-4循环比对照高。maximus与NAD-ME物种非常相似，只有少数例外，例如转移酸产生的亚细胞位置和编码C-4酶的基因的上调程度和模式。一个额外的线粒体转运蛋白与核心周期。广泛的比较确定了蔗糖和淀粉的合成，以及防止C-4循环中间体泄漏到其他代谢途径，作为C-4代谢的关键组成部分。细胞间运输通量的估计表明，细胞间的通量增加了至少两个数量级的C-4物种相比，C-3物种。与NAD-ME和NADP-ME物种相反，PEP-CK中光合电子传递蛋白的转录没有变化。综上所述，M. maximus似乎比NAD-ME和NADP-ME植物更简单。
C-4 photosynthesis affords higher photosynthetic carbon conversion efficiency than C-3 photosynthesis and it therefore represents an attractive target for engineering efforts aiming to improve crop productivity. To this end, blueprints are required that reflect C-4 metabolism as closely as possible. Such blueprints have been derived from comparative transcriptome analyses of C-3 species with related C-4 species belonging to the NAD-malic enzyme (NAD-ME) and NADP-ME subgroups of C-4 photosynthesis. However, a comparison between C-3 and the phosphoenolpyruvate carboxykinase (PEP-CK) subtype of C-4 photosynthesis is still missing. An integrative analysis of all three C-4 subtypes has also not been possible to date, since no comparison has been available for closely related C-3 and PEP-CK C-4 species. To generate the data, the guinea grass Megathyrsus maximus, which represents a PEP-CK species, was analysed in comparison with a closely related C-3 sister species, Dichanthelium clandestinum, and with publicly available sets of RNA-Seq data from C-4 species belonging to the NAD-ME and NADP-ME subgroups. The data indicate that the core C-4 cycle of the PEP-CK grass M. maximus is quite similar to that of NAD-ME species with only a few exceptions, such as the subcellular location of transfer acid production and the degree and pattern of up-regulation of genes encoding C-4 enzymes. One additional mitochondrial transporter protein was associated with the core cycle. The broad comparison identified sucrose and starch synthesis, as well as the prevention of leakage of C-4 cycle intermediates to other metabolic pathways, as critical components of C-4 metabolism. Estimation of intercellular transport fluxes indicated that flux between cells is increased by at least two orders of magnitude in C-4 species compared with C-3 species. In contrast to NAD-ME and NADP-ME species, the transcription of photosynthetic electron transfer proteins was unchanged in PEP-CK. In summary, the PEP-CK blueprint of M. maximus appears to be simpler than those of NAD-ME and NADP-ME plants.