Reactive oxygen species, oxidative signaling and the regulation of photosynthesis.

Insights into chloroplast biogenesis and development.

C4 photosynthesis is a complex physiological adaptation that confers greater productivity than the ancestral C3 photosynthetic type in environments where photorespiration is high. It evolved in multiple lineages through the coordination of anatomical and biochemical components, which concentrate CO2 at the active site of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). In most C4 plants, the CO2-concentrating mechanism is achieved via the confinement of Rubisco to bundle-sheath cells, into which CO2 is biochemically pumped from surrounding mesophyll cells. The C4 biochemical pathway relies on a specific suite of leaf functional properties, often referred to as Kranz anatomy. These include the existence of discrete compartments differentially connected to the atmosphere, a close contact between these compartments, and a relatively large compartment to host the Calvin cycle. In this review, we use a quantitative dataset for grasses (Poaceae) and examples from other groups to isolate the changes in anatomical characteristics that generate these functional properties, including changes in the size, number, and distribution of different cell types. These underlying anatomical characteristics vary among C4 origins, as similar functions emerged via different modifications of anatomical characteristics. In addition, the quantitative characteristics of leaves all vary continuously across C3 and C4 taxa, resulting in C4-like values in some C3 taxa. These observations suggest that the evolution of C4-suitable anatomy might require relatively few changes in plant lineages with anatomical predispositions. Furthermore, the distribution of anatomical traits across C3 and C4 taxa has important implications for the functional diversity observed among C4 lineages and for the approaches used to identify genetic determinants of C4 anatomy.

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Deconstructing Kranz anatomy to understand C4 evolution

C4 photosynthesis outperforms the ancestral C3 state in a wide range of natural and agro-ecosystems by affording higher water-use and nitrogen-use efficiencies. It therefore represents a prime target for engineering novel, high-yielding crops by introducing the trait into C3 backgrounds. However, the genetic architecture of C4 photosynthesis remains largely unknown. To define the divergence in gene expression modules between C3 and C4 photosynthesis during leaf ontogeny, we generated comprehensive transcriptome atlases of two Cleomaceae species, Gynandropsis gynandra (C4) and Tarenaya hassleriana (C3), by RNA sequencing. Overall, the gene expression profiles appear remarkably similar between the C3 and C4 species. We found that known C4 genes were recruited to photosynthesis from different expression domains in C3, including typical housekeeping gene expression patterns in various tissues as well as individual heterotrophic tissues. Furthermore, we identified a structure-related module recruited from the C3 root. Comparison of gene expression patterns with anatomy during leaf ontogeny provided insight into genetic features of Kranz anatomy. Altered expression of developmental factors and cell cycle genes is associated with a higher degree of endoreduplication in enlarged C4 bundle sheath cells. A delay in mesophyll differentiation apparent both in the leaf anatomy and the transcriptome allows for extended vein formation in the C4 leaf.

Comparative Transcriptome Atlases Reveal Altered Gene Expression Modules between Two Cleomaceae C3 and C4 Plant Species

Complex signaling networks between the chloroplast and the nucleus mediate the emergence of the seedling into the light and the establishment of photosynthesis.

Retrograde Signals Navigate the Path to Chloroplast Development

一片植物叶的发展是生产包括多样的细胞类型的一个复杂器官的事件的一个细致地安排的序列。叶上色异种的 reticulate 班在叶肉房间的发展由于特定的错误显示在静脉和 interveinal 区域之间的形成对照的色素沉着。因此， reticulate 异种提供一个有势力工具调查 cell-type-specific 发展过程。大多数异种在强烈在联系 vasculature 的纸巾被表示的质体局部性的、新陈代谢的小径被影响的发现含有为在叶肉房间的合适的开发的捆鞘和他们的叶绿体的一个关键角色。这里，我们考察 reticulate 异种和他们的 phenotypic 特征，与在 Arabidopsis thaliana 的那些的一个焦点。二个其他的模型被提出了解释在质体新陈代谢和叶肉房间开发之间的关系，我们这里把它称为供应和发信号的假设。我们极其估计这些建议模型并且在 C3 种类为叶开发和捆鞘功能讨论他们的含意。reticulate 异种的描述支持质体的意义后退在 C3 光合作用在细胞开发和热点表明捆鞘的意义。

Andreas

Papers

Plastid Signals and the Bundle Sheath： Mesophyll Development in Reticulate Mutants

The Influence of Naturalness, Attractiveness and Intensity on Facial Emotion Recognition

Geophysical, Petrographic and Geochemical Survey on the Nazca Lines