Project description:Elucidating the genetic control of C3 and C4 photosynthesis. Atriplex rosea (C4) and Atriplex prostrata (C3) were at maturity to compare expression between C3 and C4 in leaves, stems, and roots. Their F1 hybrid leaf was studied at maturity and will aid in identifying regulatory elements involved in C3 and C4 leaf development. Two C3 Atriplex prostrata x C4 Atriplex rosea F3 hybrids (F3003 and F3036) were sequenced at a mature leaf stage.
Project description:Elucidating the genetic control of development of C3 and C4 photosynthesis. Atriplex rosea (C4) and Atriplex prostrata (C3) were studied along a leaf developmental gradient to compare development between C3 and C4. C3 Atriplex prostrata x C4 Atriplex rosea F1 hybrid were studied along the same developmental gradient and will aid in identifying regulatory elements involved in C3 and C4 leaf development.
Project description:The C4 pathway is a highly complex trait that increases photosynthetic efficiency in over sixty plant lineages. Although the majority of C4 plants occupy disturbed, arid and nutrient-poor habitats, some grow in high-nutrient, waterlogged conditions. One such example is Echinochloa glabrescens, which is an aggressive weed of rice paddies. We generated comprehensive transcriptome datasets for C4 E. glabrescens and C3 rice to identify genes associated with adaption to waterlogged, nutrient-replete conditions, but also used the data to better understand how C4 photosynthesis operates in these conditions. Similar to arid C4 species, leaves of E. glabrescens exhibited classical Kranz anatomy with lightly lobed mesophyll cells. As with rice and other hygrophytic C3 species, leaves of E. glabrescens accumulated a chloroplastic phosphoenolpyruvate carboxylase protein, albeit at reduced levels relative to rice. We identified a molecular signature associated with C4 photosynthesis in nutrient-replete, waterlogged conditions that is highly similar to those previously reported from C4 plants that grow in more arid conditions. We also identified a cohort of genes that have been subjected to a selective sweep associated with growth in paddy conditions. Overall, this approach highlights the value of using wild species such as weeds to identify adaptions to specific conditions associated with high-yielding crops in agriculture.
Project description:In multicellular systems changes to the patterning of gene expression drive modifications in cell function and trait evolution. One striking example is found in more than sixty plant lineages where compartmentation of photosynthesis between cell types allowed evolution of the efficient C4 pathway from the ancestral C3 state. The molecular events enabling this transition are unclear. We used single nuclei sequencing to generate a cell level expression atlas for C3 rice and C4 sorghum during photomorphogenesis. In both species a conserved cistrome was identified for each cell type and initiation of photosynthesis gene expression was conditioned by cell identity. Photosynthesis genes switching expression from mesophyll in rice to bundle sheath in sorghum acquire hallmarks of bundle sheath identity. The sorghum bundle sheath has also acquired gene networks associated with C3 guard cells. We conclude C4 photosynthesis is based on rewiring in cis that exapts cell identity networks of C3 plants.
Project description:Evolution of C4 photosynthesis is not distributed evenly in the plant kingdom. Particularly interesting is the situation in the Brassicaceae, because the family contains no C4 species, but several C3-C4 intermediates, mainly in the genus Moricandia Investigation of leaf anatomy, gas exchange parameters, the metabolome, and the transcriptome of two C3-C4 intermediate Moricandia species, M. arvensis and M. suffruticosa, and their close C3 relative M. moricandioides enabled us to unravel the specific C3-C4 characteristics in these Moricandia lines. Reduced CO2 compensation points in these lines were accompanied by anatomical adjustments, such as centripetal concentration of organelles in the bundle sheath, and metabolic adjustments, such as the balancing of C and N metabolism between mesophyll and bundle sheath cells by multiple pathways. Evolution from C3 to C3-C4 intermediacy was probably facilitated first by loss of one copy of the glycine decarboxylase P-protein, followed by dominant activity of a bundle sheath-specific element in its promoter. In contrast to recent models, installation of the C3-C4 pathway was not accompanied by enhanced activity of the C4 cycle. Our results indicate that metabolic limitations connected to N metabolism or anatomical limitations connected to vein density could have constrained evolution of C4 in Moricandia.
Project description:Plasmodesmata (PD) are nanochannels that facilitate cell-to-cell transport in plants. More productive and photosynthetically efficient C4 plants form more PD at the mesophyll (M)-bundle sheath (BS) interface in their leaves than their less efficient C3 relatives. In C4 leaves, PD play an essential role in facilitating the rapid metabolite exchange between the M and BS cells to operate a biochemical CO2 concentrating mechanism, which increases the CO2 partial pressure at the site of Rubisco in the BS cells and hence photosynthetic efficiency. The genetic mechanism controlling PD formation in C3 and C4 leaves is largely unknown, especially in monocot crops, due to the technical challenge of quantifying these nanostructures with electron microscopy. To address this issue, we have generated stably transformed lines of Oryza sativa (rice, C3) and Setaria viridis (setaria, C4) with fluorescent protein-tagged PD to build the first spatiotemporal atlas of leaf pit field (cluster of PD) density in monocots without the need for electron microscopy. Across leaf development, setaria had consistently more PD connections at the M-BS wall interface than rice while the difference in M-M pit field density varied. While light was a critical trigger of PD formation, cell type and function determined leaf pit field density. Complementary temporal mRNA sequencing and gene co-expression network analysis revealed that the pattern of pit field density correlated with differentially expressed PD-associated genes and photosynthesis-related genes. PD-associated genes identified from our co-expression network analysis are related to cell wall expansion, translation and chloroplast signalling.
Project description:C4 photosynthesis was evolved from ancestral C3 photosynthesis by recruited pre-existed genes to perform new functions. Enzymes and transporters required for C4 metabolic pathway has been well documented, however, transcriptional factors (TFs) that regulate those C4 metabolic genes is poorly understood, in particular, how the TF regulatory network of C4 metabolic genes was re-wired, and the involved metabolic functions of those TFs along the evolution of C4 photosynthesis remained unknown. Here, by using RNA-Seq data from growth condition that reported to have effect on C4 photosynthesis, we constructed the TF regulatory network for four evolutionarily closely related species in the genus Flaveria, which represent different stages of the evolution of C4 photosynthesis, namely, C3, type I C3-C4, type II C3-C4 and C4. Our results show that four TFs are conserved along the evolution whose function either relate to stress response or light response. TFs regulating C4 core genes in C3 species involved in functions belong to RNA regulation and nitrogen metabolism, and that in both intermediate species and C4 species involved in photosynthesis and light responsiveness. Moreover, the TF-network of C4 core metabolic genes has the highest network density in type I C3-C4 species and C4 species when consider the fragment of TF-regulatory network that up-regulated under low CO2, suggesting that TFs regulating C4 genes were recruited to photosynthesis at type I C3-C4 both in involved functions and network density. Our results provide a valuable resource for studying molecular regulatory mechanisms underlying C4 metabolic process.
Project description:C4 photosynthesis was evolved from ancestral C3 photosynthesis by recruited pre-existed genes to perform new functions. Enzymes and transporters required for C4 metabolic pathway has been well documented, however, transcriptional factors (TFs) that regulate those C4 metabolic genes is poorly understood, in particular, how the TF regulatory network of C4 metabolic genes was re-wired, and the involved metabolic functions of those TFs along the evolution of C4 photosynthesis remained unknown. Here, by using RNA-Seq data from growth condition that reported to have effect on C4 photosynthesis, we constructed the TF regulatory network for four evolutionarily closely related species in the genus Flaveria, which represent different stages of the evolution of C4 photosynthesis, namely, C3, type I C3-C4, type II C3-C4 and C4. Our results show that four TFs are conserved along the evolution whose function either relate to stress response or light response. TFs regulating C4 core genes in C3 species involved in functions belong to RNA regulation and nitrogen metabolism, and that in both intermediate species and C4 species involved in photosynthesis and light responsiveness. Moreover, the TF-network of C4 core metabolic genes has the highest network density in type I C3-C4 species and C4 species when consider the fragment of TF-regulatory network that up-regulated under low CO2, suggesting that TFs regulating C4 genes were recruited to photosynthesis at type I C3-C4 both in involved functions and network density. Our results provide a valuable resource for studying molecular regulatory mechanisms underlying C4 metabolic process.
Project description:C4 photosynthesis was evolved from ancestral C3 photosynthesis by recruited pre-existed genes to perform new functions. Enzymes and transporters required for C4 metabolic pathway has been well documented, however, transcriptional factors (TFs) that regulate those C4 metabolic genes is poorly understood, in particular, how the TF regulatory network of C4 metabolic genes was re-wired, and the involved metabolic functions of those TFs along the evolution of C4 photosynthesis remained unknown. Here, by using RNA-Seq data from growth condition that reported to have effect on C4 photosynthesis, we constructed the TF regulatory network for four evolutionarily closely related species in the genus Flaveria, which represent different stages of the evolution of C4 photosynthesis, namely, C3, type I C3-C4, type II C3-C4 and C4. Our results show that four TFs are conserved along the evolution whose function either relate to stress response or light response. TFs regulating C4 core genes in C3 species involved in functions belong to RNA regulation and nitrogen metabolism, and that in both intermediate species and C4 species involved in photosynthesis and light responsiveness. Moreover, the TF-network of C4 core metabolic genes has the highest network density in type I C3-C4 species and C4 species when consider the fragment of TF-regulatory network that up-regulated under low CO2, suggesting that TFs regulating C4 genes were recruited to photosynthesis at type I C3-C4 both in involved functions and network density. Our results provide a valuable resource for studying molecular regulatory mechanisms underlying C4 metabolic process.