As recent advances in gene editing technologies have enabled rapid and accurate modification of target genes, new varieties are being developed through the application of gene editing technologies in various crop species. In particular, the CRISPR/Cas9 system has become a tool of choice for gene editing because it is much more economical and efficient than previous tools such as ZFN and TALEN, and is being actively used to improve various breeding traits, including biotic and abiotic stress tolerance to overcome the limitations of conventional plant breeding technologies. In this review, we retrieved 210 papers describing the utilization of CRISPR/Cas9 in rice published between 2013 and 2021 and classified them according to the field of study and traits of interest. Further case studies were conducted on 21 and 12 research papers that reported the enhancement of biotic and abiotic stress tolerance, respectively. This demonstrated that CRISPR/Cas9-based gene editing can be highly effective in improving resistance to bacterial (bacterial leaf blight and bacterial leaf streak), fungal (blast, sheath blight), and viral (rice tungro spherical virus, rice black streak virus) diseases as well as various abiotic stresses, including drought, salinity, cold, and heat, in many cases, without diminishing important agronomic traits. As recent technological advances have begun to overcome the major limitations of CRISPR/Cas9 gene editing, such as low HDR efficiency and off-target effects, it is expected that more research on gene function and cultivar development will adopt CRISPR/Cas9 as a major gene editing tool in the future. To effectively apply such innovative technologies in crop improvement, much effort is required to establish more reasonable and detailed policies for regulating crops developed through new breeding technologies.

New Breeding Technology (NBT) refers to gene editing technologies that are used to develop crop plants with beneficial traits, from biotic/abiotic resistance to nutritional enhancement, including zinc finger nucleases (ZFN), transcription activator-like effector nucleases, clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9, meganucleases, and oligo directed mutagenesis. A total of 1,119 valid NBT patents were analyzed in this study to examine global trends in the patent and market expansion strategies for major patent applicants. Based on the claims specified, valid patents in each patent office were analyzed through the applicant’s country of origin, field of technology, and plant/crop species. Patents claiming applications of CRISPR-based technology to major crop plants, including rice, corn, wheat, tomato, and canola, have rapidly increased in the China National Intellectual Property Administration (CNIPA) since 2013. The patent family size (PFS) can be used as an indicator of intellectual property (IP)-based market expansion strategies and target markets of interests of patent applicants. Many university- and research-oriented institution Chinese applicants showed low PFS (2.1) because they filed patents mostly in CNIPA. In contrast, high PFS of US and German (DE) applicants such as Corteva Agriscience (US), KWS SAAT AG (DE), Cellectics (FR), and Syngenta Participations AG (CH) represented their active strategies for global gene-edited crop market expansion. Corteva Agriscience (US, 238 patents) was the global leader in patents using NBT, ranging from ZFN to CRISPR-based technologies applied to most major crops, including corn, soybean, and wheat.

Wheat transformation was first initiated in 1992, and several studies were conducted to increase its efficiency; however, a very low probability of less than 0.3% was achieved. In 2011, the EU Commission announced a new plant breeding technology that modifies the DNA of seeds and plant cells to develop new varieties with desired characteristics. With the commercialization of the CRISPR/Cas9 technology, a site-directed nuclease technology, the possibility of its application in agriculture has increased with the rapid development of the technology. Recently, genome editing studies have been conducted in wheat, and they have been used for the functional analysis of genes related to various agricultural traits. The wheat full-length genome information was released in the form of a draft sequence in 2018, belatedly in comparison to other crops owing to allohexaploidy and a large genome (17 Gb) size. The recent pre-harvest sprouting resistance wheat breeding material developed in Japan suggests that it is possible to rapidly develop breeding materials through precision breeding technology. Finally, it is necessary to systematically achieve the goal of optimizing agricultural traits of crops through precise breeding technology to increase the breeding accuracy of allohexaploid wheat and rapid genetic fixation using the reduction in generation technology.

In recent years, new plant breeding technologies (NPBT) have had enormous effects on breeding and the agricultural industry. In particular, genome editing technology, including site-directed nuclease technologies, has progressed dramatically since the first-generation Zinc finger nucleases to the third-generation clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9). CRISPR/Cas9 technology has yielded a revolutionary breakthrough in the accurate, efficient, and user-friendly genome editing of eukaryotes. Several methods for basic research and applications, such as knock-out, base editing, gene targeting, and transcriptional activation or repression have been derived from CRISPR/Cas9 technology. Herein, we will describe the current progress in NPBTs and also summarize the crops developed by NPBTs. After analyzing the current status of NPBTs and crop development, we have proposed potential strategies for crop development using NPBTs.