Ya Liu

The gene-editing tool Cas-SF01 was optimized to maximize its efficiency in maize. The Cas-SF01-TREX2 configuration was superior in enabling high-purity gene mutations. This toolkit enabled commercial maize to flower seven days earlier without yield loss, thereby securing harvests and accelerating crop breeding.

In the present study, we have successfully established a gene editing platform in broomcorn millet, one of the oldest crops originating from China, by using our CRISPR/Cas12i.3, and we also created new elite germplasm for this crop.

Drought is a major abiotic stress that harms plant cell physiology and limits the growth and productivity of crops. Maize (Zea maysL.), one of the most drought-susceptible crops, is a major food source for humans and an important resource for industrial bioenergy production; therefore, understanding the mechanisms of the drought response is essential for maize improvement. Using isotopic tagging relative quantitation (iTRAQ)-based protein labeling technology, we detected the proteomic changes in maize leaves under drought stress. Among the 3063 proteins that were identified, the abundance of 214 and 148 proteins increased and decreased, respectively, after three days of drought treatment. These differentially abundant proteins (DAPs) were mainly involved in cell redox homeostasis, cell wall organization, photosynthesis, abscisic acid biosynthesis, and stress-response processes. Furthermore, some of the DAP abundances still differed from the control six days after the drought treatment, most of which were molecular chaperones, heat shock proteins, metabolism-related enzymes, hydrolases, and transmembrane signal receptors. The expression level of some DAPs returned to normal when the water supply was restored, but for others it did not. A significant correlation between the protein and transcript levels was observed following an RT-qPCR analysis. Finally, our research provides insights into the overall mechanism of drought-stress tolerance, and important information for breeding of drought-tolerant maize.

Progress through the cell cycle is a critical process during plant embryo and seed development and its progression is regulated by cyclins. Despite extensive study of cyclins in other systems, their role in embryo and seed development of maize is unclear. In this study, we demonstrate that ZmCYCB1-1 overexpression significantly accelerated embryo growth and increased seed size. In situ hybridization and toluidine blue staining indicated that ZmCYCB1-1 was highly expressed in the plumule of embryos, and the cells of the plumule were smaller, denser, and more regularly arranged in ZmCYCB1-1 overexpression plants. Overexpression of ZmCYCB1-1 in maize also resulted in an increased ear length and enhanced kernel weight by increasing kernel width. Transcriptome analysis indicated that the overexpression of ZmCYCB1-1 affected several different metabolic pathways, including photosynthesis in embryos and leaves, and lipid metabolism in leaves. Conversely, knocking out ZmCYCB1-1 resulted in plants with slow growth. Our results suggest that ZmCYCB1-1 regulates embryo growth and seed size, making it an ideal target for efforts aimed at maize yield improvement.

Maize (Zea mays) is one of the most important crops in the world. However, few agronomically important maize genes have been cloned and used for trait improvement, due to its complex genome and genetic architecture. Here, we integrated multiplexed CRISPR/Cas9-based high-throughput targeted mutagenesis with genetic mapping and genomic approaches to successfully target 743 candidate genes corresponding to traits relevant for agronomy and nutrition. After low-cost barcode-based deep sequencing, 412 edited sequences covering 118 genes were precisely identified from individuals showing clear phenotypic changes. The profiles of the associated gene-editing events were similar to those identified in human cell lines and consequently are predictable using an existing algorithm originally designed for human studies. We observed unexpected but frequent homology-directed repair through endogenous templates that was likely caused by spatial contact between distinct chromosomes. Based on the characterization and interpretation of gene function from several examples, we demonstrate that the integration of forward and reverse genetics via a targeted mutagenesis library promises rapid validation of important agronomic genes for crops with complex genomes. Beyond specific findings, this study also guides further optimization of high-throughput CRISPR experiments in plants.