Due to their simplicity and high efficiency, CRISPR/Cas systems provide efficient tools for functional genomics and crop molecular breeding. In this review, we summarize the current developments of CRISPR/Cas genomic editing systems in plants and compare the differences between these systems and their derivative technologies. We review the applications of CRISPR/Cas9 editing technology in maize improvement focusing on yield, quality, disease resistance, abiotic stress resistance, male sterile line development and haploid induction. Finally, we discuss the future improvement of CRISPR/Cas systems and provide perspectives on prospect genome editing technologies.
Maize is the largest cultivated grain crop in the world. To increase maize yield and meet human’s needs, genetic modification has become an effective breeding tool for maize improvement. Since commercial GM (genetically modified) maize was planted in the United States in 1996, genetic transformation has achieved a great success in developing commercialized GM maize. This article reviews the important steps during maize genetic transformation, summarizes the commercial development of transgenic maize varieties, and suggests the optimization of maize genetic transformation system, the safety of transgenic maize, and the commercial development of more GM maize varieties.
As the birthplace of crop gene editing technology, EU and USA have initially formed a complete industrial technology chain layout from basic research to technology development services to breeding application, as well as a risk management system. This study will comprehensively summarize the latest progress and trend of global crop gene editing supervision, and put forward countermeasures and suggestions for China’s gene editing technology risk management, in order to narrow the gap between gene editing technology progress and regulatory policy system as soon as possible.
Ear is an important reproductive organ of maize. The development of ear determines the size of mature ear and the weight of single ear, and then directly affects the yield of maize. Ear traits include ear length, ear diameter, kernel row number, kernel number per row, ear weight, and kernel weight per ear, which are quantitative genetic traits controlled by multiple genes, and their genetic structures are different. It is effective to increase maize yield by analyzing the genetic basis of the traits of ear and optimizing the structure of ear. Through quantitative trait locus(QTL) mapping, genome-wide association study (GWAS) and other approaches, many loci related to ear traits have been identified, but at present, there are few ear-trait-related genes were cloned, and the consistent map of the identified genetic loci is not complete, so it is difficult to reveal the genetic structure of ear traits comprehensively. Based on the previous progress in genetic mapping of ear traits, the identified QTLs and significantly associated SNPs were integrated into the V4 version of maize B73 reference genome, and the genetic hotspots for ear traits were identified. The work is valuable for further analysis of the genetic structure of ear traits, cloning ear-trait-related genes and dissecting the molecular mechanism of ear development.
Maize is the crop with the largest planting area and the highest yield in the world. Starch accounts for about 70% of its grain weight, which is not only the main energy source for human beings and other animals, but also an important raw material for chemical industry. Assisted by the research on Arabidopsis thaliana, rice and other model plants, there have been accumulated a lot of information about the main biological processes of starch synthesis and functions of related gene in plants. Recently, many new starch content-related loci and candidate genes have been also further discovered through quantitative trait loci (QTL) mapping, genome-wide association study (GWAS) and omics-based methods in maize and other plants. However, summarization about such information is currently limited in maize. Here, the research progress of starch synthesis and regulation mechanisms in maize kernel were reviewed, and the QTLs and genes related to starch content in maize kernel were summarized and analyzed. The consistent physical map for starch content in maize kernel was further constructed, and the genetic hotspots were identified. The data will be useful for further deciphering the genetic basis of starch content in maize kernel and for molecular marker-assisted selection in maize breeding.
Plant height and ear height are important agronomic traits of maize, which directly affect the nutrient utilization efficiency and lodging resistance of the plant, and ultimately affect the yield of maize. Plant height and ear height are typical quantitative traits, and quantitative trait loci (QTL) mapping and genome-wide association study (GWAS) have been used to mine the related genetic loci. Some key genes regulating plant height and ear height were cloned by fine-mapping or by using mutants. However, due to the differences in type and size of mapping populations, type and density of the markers and statistical methods used by different research groups, the identified QTL was divergent significantly, and it was difficult to reveal the genetic structure of plant height and ear height of maize by single study. The identified QTLs were mainly based on genetic maps at early stages, and the versions of maize reference genome were updated several times, which hampered the efficient utilization of previously identified QTLs. Here, the mapping information of plant height and ear height was normalized and integrated into the V4 version of the maize inbred line B73 reference genome, and a consistent physical map for plant height and ear height was constructed. Furthermore, the mapping hotspots of plant height and ear height were identified by combining the results from independent studies. The cloned genes regulating both traits were also summarized. This study is of great significance for the in-depth dissection of the genetic structure of plant height and ear height, as well as for aiding gene cloning and marker-assisted selection in molecular breeding.
Maize yield is determined by the efficiency of plant capturing light energy and fixing CO2 into organic carbon compounds. Leaf angle (LA) is one of the important traits of plant architecture, and smaller leaf angle is beneficial to improving the photosynthetic efficiency, planting density, and ultimately the increase of the yield of maize. Previous studies have shown that LA of maize is a complex quantitative trait controlled by multiple genes with higher heritability and significant contribution of additive genetic effects. At present, hundreds of quantitative trait loci (QTLs) related to LA in maize have been identified by QTL mapping and genome-wide association study (GWAS). Combined with mutant analysis, dozens of key genes regulating LA have also been cloned, which provides an important clue for understanding the genetic mechanism of LA in maize. Previous studies have used different populations, analysis models and even reference genome versions for maize LA genetic analysis, the identified QTLs were quite different in those studies, which hampered the understanding of genetic structure of LA traits. Therefore, in this study, we summarized the mapped QTLs and associated single nucleotide polymorphisms (SNPs) related to LA and constructed a consistent map, and then identified the genetic hot spots of LA. Finally, the cloned functional genes regulating LA were analyzed and classified. Our work not only provides primary data for understanding the genetic structure of maize LA and promoting the cloning of the candidate genes, but also provides useful molecular markers for molecular marker-assisted breeding and maize yield improvement.
Maize is a monoecious plant with top terminal tassels and lateral ears. The tassels need to produce sufficient pollens to fertilize ears; however, due to the shading effect on the lower leaves and their own nutritional requirements, the growth and development of tassels have a negative effect on yield through affecting leaf photosynthesis and energy distribution of the whole plant. Optimizing the tassel architecture is thus urgent for maize yield improvement. Maize tassel traits include the number of tassel branches, the length of tassel branches, the length of the principal axis of the tassel, the total length of tassel branches, and the angle of tassel branching, which are all complex quantitative traits controlled by different genetic basis. Since the 1990s, researchers have begun to analyze the genetic structure of maize tassel traits by quantitative trait locus(QTL) mapping. With the release of the reference genome of the maize inbred line B73, and the improvement of high-throughput genotyping technologies such as DNA microarrays and genome resequencing, genome-wide association study(GWAS) has been widely applied in recent years, and a large number of loci associated with the maize tassel traits have been identified. Here, the genetic loci of maize tassel traits identified from different research periods were retrieved, and a consistent physical map was built. Furthermore, the genetic mapping hotspots were isolated which will be useful for the further understanding of the genetic structure of maize tassel traits and the guidance of the cloning of tassel-trait-related genes. At the same time, the cloned genes controlling tassel traits and the corresponding functional mechanism were summarized which will be helpful for further deciphering the genetic network and regulatory pathways of tassel development in maize.
Maize is a major staple crop and its yield accounts for about one-third of the total cereal production in China. Maize development is affected by multiple diseases during its growth process, among which ear rot is caused by several fungal species. Up to now, more than 40 fungal species that can induce ear rot have been identified. Ear rot can not only cause the loss of maize yield, but also lead to the serious decline of grain quality, and the mycotoxins produced by fungi species have detrimental effects on animal and human health. Ear rot control is still mainly based on chemical approaches, but it increases the cost of maize production and the risk of environmental pollution, breeding of resistant varieties should be the most economical, safe and effective method. Maize resistance to ear rot is a typical quantitative trait, research systems grading this trait have been established, and multiple maize varieties with high resistance to ear rot were isolated, which provided valuable material basis for genetic improvement of maize resistance to ear rot. Quantitative trait locus (QTL) mapping and genome-wide association study (GWAS) showed that maize resistance to ear rot related QTLs distribute throughout the maize 10 chromosomes. However, few QTLs were applied to molecular breeding through marker-assisted-selection. This is possibly caused by the complexity of genetic architecture of maize resistance to ear rot, the difficulty of cloning of resistance genes, and the lack of systematic summary of the genetic research progress. In this study, we reviewed the progress of genetic research on maize resistance to ear rot, constructed a consistent physical map based on the results from QTL mapping or GWAS, and identified the mapping hotspots. Meanwhile, a comparative analysis between the candidate genes within the hotspots and the transcriptomic and metabolomic data from previous study were also conducted. Our work will provide valuable data for deciphering the mechanism of maize resistance to ear rot and provide important genetic resource for maize resistance breeding.
With the development of synthetic biology, gene editing and other typical dual-use emerging biotechnology, biosafety, as a significant interdisciplinary area, has attracted wide attention. Using the papers data from Web of Science, this study analyzed the interdisciplinary status and temporal evolution of biosafety research based on journal discipline category, and studied the differences of interdisciplinary tendency in different countries by enrichment analysis. The results show that since the 20th century, the interdisciplinarity of biosafety research and other disciplines has become more extensive. Animal and plant science, environment and ecology, social science, microbiology and agricultural science are the most interdisciplinary areas. The interdisciplinary situation of biosafety research in different countries was different, and the interdisciplinary situation in American and European countries has a valuable reference for China. This study is expected to provide a exploration of new methods for interdisciplinary study research in specific research fields, and to provide reference for strengthening the interdisciplinary and exploring new research directions of biosafety research in our country.
The COVID-19 epidemic that broke out at the end of 2019 has swept the world and seriously threatened human health. It has become a major global health and security challenge that requires the joint efforts of all countries in the world. Since different countries have different cultures, geographical locations, social systems, and economic development levels, their medical systems play different roles in epidemic prevention and control when facing the epidemic. Taking cities in the Guangdong-Hong Kong-Macao Greater Bay Area (Guangzhou, Shenzhen, Zhuhai, Hong Kong and Macau) under the epidemic situation as representatives, this paper aims to systematically summarize and quantitatively analyze the performance and effectiveness of various medical systems in public health emergencies, and to clarify the functions of medical institutions, medical staff, medical supplies, etc., as well as elucidate their advantages and shortcomings in the prevention and control of major infectious epidemics. The results show that in comparison to Hong Kong and Macao, the three cities in the mainland of China have a strong foundation of epidemic prevention medical system; Macao and the three cities in the mainland maintained a high degree of consistency in the early stage of the epidemic, and jointly promoted the mechanism of tackling key epidemic prevention problems, which performed well in the effectiveness of responding to the epidemic. However, due to the positioning restriction of the “international shipping center”and the impact of social tearing aftershocks, Hong Kong was difficult to quickly and comprehensively lock up, and the effectiveness of responding to the epidemic was slightly poor. In the future, Guangdong-Hong Kong-Macao Greater Bay Area should exchange and complement each other and share resources to jointly improve the public health emergency response capacity of the whole area.
The biotechnology base platform for technological innovation and achievement transformation is an important platform for conducting key technology research, and promoting application demonstration, achievement transformation and industrialization in the field of biotechnology. Through analyzing and researching the current situation of the development of China’s technology innovation and transformation base platforms in recent years, the article explores the role of biotechnology base platforms in biotechnology innovation and transformation, summarizes the advantages and shortcomings, and provides reference for the future development and construction.
