Simultaneous targeting of duplicated genes in Petunia protoplasts for flower color modification via CRISPR-Cas9 ribonucleoproteins.

KEY MESSAGE: We obtained a complete mutant line of Petunia having mutations in both F3H genes via Cas9-ribonucleoproteins delivery, which exhibited a pale purplish pink flower color. The CRISPR-Cas system is now revolutionizing agriculture by allowing researchers to generate various desired mutations in plants at will. In particular, DNA-free genome editing via Cas9-ribonucleoproteins (RNPs) delivery has many advantages in plants; it does not require codon optimization or specific promoters for expression in plant cells; furthermore, it can bypass GMO regulations in some countries. Here, we have performed site-specific mutagenesis in Petunia to engineer flower color modifications. We determined that the commercial Petunia cultivar 'Madness Midnight' has two F3H coding genes and designed one guide RNA that targets both F3H genes at once. Among 67 T0 plants regenerated from Cas9-RNP transfected protoplasts, we obtained seven mutant lines that contain mutations in either F3HA or F3HB gene and one complete mutant line having mutations in both F3H genes without any selectable markers. It is noteworthy that only the f3ha f3hb exhibited a clearly modified, pale purplish pink flower color (RHS 69D), whereas the others, including the single copy gene knock-out plants, displayed purple violet (RHS 93A) flowers similar to the wild-type Petunia. To the best of our knowledge, we demonstrated a precedent of ornamental crop engineering by DNA-free CRISPR method for the first time, which will greatly accelerate a transition from a laboratory to a farmer's field.

One-step inverse generation network for sparse-view dual-energy CT reconstruction and material imaging.

Objective.Sparse-view dual-energy spectral computed tomography (DECT) imaging is a challenging inverse problem. Due to the incompleteness of the collected data, the presence of streak artifacts can result in the degradation of reconstructed spectral images. The subsequent material decomposition task in DECT can further lead to the amplification of artifacts and noise.Approach.To address this problem, we propose a novel one-step inverse generation network (OIGN) for sparse-view dual-energy CT imaging, which can achieve simultaneous imaging of spectral images and materials. The entire OIGN consists of five sub-networks that form four modules, including the pre-reconstruction module, the pre-decomposition module, and the following residual filtering module and residual decomposition module. The residual feedback mechanism is introduced to synchronize the optimization of spectral CT images and materials.Main results.Numerical simulation experiments show that the OIGN has better performance on both reconstruction and material decomposition than other state-of-the-art spectral CT imaging algorithms. OIGN also demonstrates high imaging efficiency by completing two high-quality imaging tasks in just 50 seconds. Additionally, anti-noise testing is conducted to evaluate the robustness of OIGN.Significance.These findings have great potential in high-quality multi-task spectral CT imaging in clinical diagnosis.