GSE137938
The evolution of TF-regulatory network of core C4 metabolic pathway genes in the genus of Flaveria [ABA]
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. Overall design: For low CO2 experiment, Plants were grown in growth chamber with light intensity to be 200 µmol m-2 s-1 and temperature to be 22oC, 16h/8h light/ dark duration, 70% humidity. Plants for ABA experiment were grown in green house of SIPPE, SIBS, CAS, the light intensity was controlled to be 500 µmol m-2 s-1, and temperature to be 25oC, 16h/8h light/ dark duration, 70% humidity. A concentration of 40 µM ABA dissolved in distill H2O was sprayed to mature leaf of one-month old plants, and the control was sprayed with distill H2O. Plants for high light experiment were grown in the greenhouse in the Partner institute of computational biology, SIBS, CAS, with high light to be 1400 µmol m-2 s-1 and control to be 500 µmol m-2 s-1. The high light was achieved by given additive light from self-made light source. For all the experiments, plant were watered twice a week and fertilized weekly.