Project description:Crassulacean acid metabolism (CAM) is a water-use efficient adaptation of photosynthesis that has evolved independently many times in diverse lineages of flowering plants. We hypothesize that convergent evolution of protein sequence and temporal gene expression underpins the independent emergences of CAM from C3 photosynthesis. To test this hypothesis, we generated a de novo genome assembly and genome-wide transcript expression data for Kalanchoe fedtschenkoi, an obligate CAM species within the core eudicots with a relatively small genome (~260 Mb). Our comparative analyses identified signatures of convergence in protein sequence and re-scheduling of diel transcript expression of genes involved in nocturnal CO2 fixation, stomatal movement, heat tolerance, circadian clock and carbohydrate metabolism in K. fedtschenkoi and other CAM species in comparison with non-CAM species. These findings provide new insights into molecular convergence and building blocks of CAM and will facilitate CAM-into-C3 photosynthesis engineering to enhance water-use efficiency in crops.
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.
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:The basic body plan and major physiological axes have been highly conserved during mammalian evolution, yet only a small fraction of the human genome sequence appears to be subject to evolutionary constraint. To quantify cis- versus trans-acting contributions to mammalian regulatory evolution, we performed genomic DNase I footprinting of the mouse genome across 25 cell and tissue types, collectively defining ~8.6 million transcription factor (TF) occupancy sites at nucleotide resolution. Here we show that mouse TF footprints conjointly encode a regulatory lexicon that is ~95% similar with that derived from human TF footprints. However, only ~20% of mouse TF footprints have human orthologues. Despite substantial turnover of the cis-regulatory landscape, nearly half of all pairwise regulatory interactions connecting mouse TF genes have been maintained in orthologous human cell types through evolutionary innovation of TF recognition sequences. Furthermore, the higher-level organization of mouse TF-to-TF connections into cellular network architectures is nearly identical with human. Our results indicate that evolutionary selection on mammalian gene regulation is targeted chiefly at the level of trans-regulatory circuitry, enabling and potentiating cis-regulatory plasticity. We performed genomic DNase I footprinting of the mouse genome across 25 cell and tissue types, collectively defining ~8.6 million transcription factor (TF) occupancy sites at nucleotide resolution.
Project description:Already a proven mechanism for drought sustainability, crassulacean acid metabolism (CAM) is a specialized type of photosynthesis that maximizes water-use efficiency (WUE) via an inverse (compared to C3 and C4 photosynthesis-performing species) day/night pattern of stomatal closure/opening to shift CO2 uptake to the nighttime, when evapotranspiration rates are low. A systems-level understanding spanning temporal molecular and metabolic controls is needed to define the cellular behavior that confers advantages in water-limited conditions. Here, we report high-resolution temporal behaviors of transcript, protein, and metabolite abundances across a CAM diel cycle and, where applicable, compare those observations to the well-established C3 model plant, Arabidopsis thaliana. A mechanistic finding that emerged is that CAM operates with a shifted altered redox poise relative to Arabidopsis thaliana. Moreover, we identify widespread rescheduled expression for genes associated with signal transduction mechanisms that are presented in guard cells to regulate stomatal opening/closing. Controlled production and degradation of transcript and proteins is a timing mechanism by which to regulate cellular function, yet knowledge of how this molecular timekeeping regulates CAM physiology is unknown. Here, we provide new insight into complex, post-transcriptional and -translational hierarchies that govern CAM in Agave. These data sets together provide a resource that could inform efforts to engineer traits of the more efficient CAM plant into economically valuable C3 crops.
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.