Showing papers by "Yuriko Osakabe published in 2021"

Genome editing in mammalian cells using the CRISPR type I-D nuclease.

Abstract: Adoption of CRISPR-Cas systems, such as CRISPR-Cas9 and CRISPR-Cas12a, has revolutionized genome engineering in recent years; however, application of genome editing with CRISPR type I-the most abundant CRISPR system in bacteria-remains less developed. Type I systems, such as type I-E, and I-F, comprise the CRISPR-associated complex for antiviral defense ('Cascade': Cas5, Cas6, Cas7, Cas8 and the small subunit) and Cas3, which degrades the target DNA; in contrast, for the sub-type CRISPR-Cas type I-D, which lacks a typical Cas3 nuclease in its CRISPR locus, the mechanism of target DNA degradation remains unknown. Here, we found that Cas10d is a functional nuclease in the type I-D system, performing the role played by Cas3 in other CRISPR-Cas type I systems. The type I-D system can be used for targeted mutagenesis of genomic DNA in human cells, directing both bi-directional long-range deletions and short insertions/deletions. Our findings suggest the CRISPR-Cas type I-D system as a unique effector pathway in CRISPR that can be repurposed for genome engineering in eukaryotic cells.

Targeted mutagenesis of CENTRORADIALIS using CRISPR/Cas9 system through the improvement of genetic transformation efficiency of tetraploid highbush blueberry

Abstract: Genome editing technology, which enables researchers to modify specific genomic loci, may be useful for accelerating the breeding of many fruit crops. The aim of this study was to evaluate the CRIS...

Effects of the sliaa9 Mutation on Shoot Elongation Growth of Tomato Cultivars.

Abstract: Tomato INDOLE-3-ACETIC ACID9 (SlIAA9) is a transcriptional repressor in auxin signal transduction, and SlIAA9 knockout tomato plants develop parthenocarpic fruits without fertilization. We generated sliaa9 mutants with parthenocarpy in several commercial tomato cultivars (Moneymaker, Rio Grande, and Ailsa Craig) using CRISPR-Cas9, and null-segregant lines in the T1 generation were isolated by self-pollination, which was confirmed by PCR and Southern blot analysis. We then estimated shoot growth phenotypes of the mutant plants under different light (low and normal) conditions. The shoot length of sliaa9 plants in Moneymaker and Rio Grande was smaller than those of wild-type cultivars in low light conditions, whereas there was not clear difference between the mutant of Ailsa Craig and the wild-type under both light conditions. Furthermore, young seedlings in Rio Grande exhibited shade avoidance response in hypocotyl growth, in which the hypocotyl lengths were increased in low light conditions, and sliaa9 mutant seedlings of Ailsa Craig exhibited enhanced responses in this phenotype. Fruit production and growth rates were similar among the sliaa9 mutant tomato cultivars. These results suggest that control mechanisms involved in the interaction of AUX/IAA9 and lights condition in elongation growth differ among commercial tomato cultivars.

Genome Editing in Apple

Abstract: Genome editing with artificially engineered nucleases is an advanced molecular technology for pursuing precise and effective genetic engineering. In this technology, engineered nucleases induce DNA double-strand breaks at targeted sites in a genome, stimulating the DNA repair system in cells, thus enabling site-directed mutagenesis. Genome editing using CRISPR (clustered regularly interspaced short palindromic repeats)/CRISPR-associated protein9 (Cas9), originating from a defence system of prokaryotes, is a powerful technology that is now being widely utilized in molecular research studies, as well as in breeding programmes of various plant species, including fruit trees, to impart either novel or enhanced traits to established commercial cultivars or to new cultivars/genotypes. Recently, several reports have demonstrated successful apple genome editing and the introduction of important traits, such as those for early flowering and reduced fire blight susceptibility, to popular commercial cultivars, such as ‘Gala’ and ‘Golden Delicious’. It is important to point out that these reports reveal that such genome-edited/mutant apple plants or cell lines do not carry foreign genes. Nevertheless, during the process of precise genome editing, the coexistence of various types of mutations referred to as “mosaic mutations” and off-target effects are major concerns. Therefore, to minimize such effects, selection of target sequences and estimation of off-target effects for CRISPR/Cas9 has been developed for many organisms, and these have also been employed for apple by using in silico analysis based on genome information. On the other hand, apple genome heterozygosity has led to difficulties in genome editing, as the complex genome of apple precludes the use of some of these basic techniques for genome editing. Therefore, further studies focused on genome information and culture techniques tailored for apple are needed. It will be highly critical for each apple cultivar in developing precise and efficient genome editing for apple. This chapter will provide an overview of current studies of genome editing in apple and will discern and explore how this strategy will provide insights into molecular breeding technologies for genetic improvement of the apple.