Mutational Analysis of OsPLDα1 Reveals Its Involvement in Phytic Acid Biosynthesis in Rice Grains

Comparative Metabolome and Transcriptome Analysis Reveals the Possible Roles of Rice Phospholipase A Genes in the Accumulation of Oil in Grains

The phospholipase A (PLA) gene family plays a crucial role in the regulation of plant growth, development and stress response. Although PLA genes have been identified in various plant species, their specific functions and characteristics in oil quality formation of rice grains (Oryza sativa L.) have not been studied yet. Here, we identified and characterized 35 rice PLA genes, which were divided into three subgroups based on gene structures and phylogenetic relationships. These genes are distributed unevenly across 11 rice chromosomes. The promoter sequence of rice PLAs contain multiple plant hormones and stress-related elements. Gene expression analyses in various tissues and under stress conditions indicated that PLAs may be involved in rice growth, development and stress response. In addition, metabolomics, transcriptomics and qRT-PCR analyses between two rice varieties Guang8B (G8B, high oil content) and YueFengB (YFB, low oil content) revealed that the different expressional levels of rice PLA genes were closely related to the differences in the oil content between 'G8B' and 'YFB' grains. The findings of this study provide potential novel insights into the molecular information of the phospholipase A gene family in rice, and underscore the potential functions of PLA genes in rice oil content accumulation, providing valuable resources for future genetic improvement and breeding strategies.

Biotechnological approaches to reduce the phytic acid content in millets to improve nutritional quality

MAIN CONCLUSION

The review article summarizes the approaches and potential targets to address the challenges of anti-nutrient like phytic acid in millet grains for nutritional improvement. Millets are a diverse group of minor cereal grains that are agriculturally important, nutritionally rich, and the oldest cereals in the human diet. The grains are important for protein, vitamins, macro and micronutrients, fibre, and energy sources. Despite a high amount of nutrients, millet grains also contain anti-nutrients that limit the proper utilization of nutrients and finally affect their dietary quality. Our study aims to outline the genomic information to identify the target areas of research for the exploration of candidate genes for nutritional importance and show the possibilities to address the presence of anti-nutrient (phytic acid) in millets. So, the physicochemical accessibility of micronutrients increases and the agronomic traits can do better. Several strategies have been adopted to minimize the phytic acid, a predominant anti-nutrient in cereal grains. In the present review, we highlight the potential of biotechnological tools and genome editing approaches to address phytic acid in millets. It also highlights the biosynthetic pathway of phytic acid and potential targets for knockout or silencing to achieve low phytic acid content in millets.

Evidence and opportunities for developing non-transgenic genome edited crops using site-directed nuclease 1 approach

The innovations and progress in genome editing/new breeding technologies have revolutionized research in the field of functional genomics and crop improvement. This revolution has expanded the horizons of agricultural research, presenting fresh possibilities for creating novel plant varieties equipped with desired traits that can effectively combat the challenges posed by climate change. However, the regulation and social acceptance of genome-edited crops still remain as major barriers. Only a few countries considered the site-directed nuclease 1 (SDN1) approach-based genome-edited plants under less or no regulation. Hence, the present review aims to comprise information on the research work conducted using SDN1 in crops by various genome editing tools. It also elucidates the promising candidate genes that can be used for editing and has listed the studies on non-transgenic crops developed through SDN1 either by Agrobacterium-mediated transformation or by ribo nucleoprotein (RNP) complex. The review also hoards the existing regulatory landscape of genome editing and provides an overview of globally commercialized genome-edited crops. These compilations will enable confidence in researchers and policymakers, across the globe, to recognize the full potential of this technology and reconsider the regulatory aspects associated with genome-edited crops. Furthermore, this compilation serves as a valuable resource for researchers embarking on the development of customized non-transgenic crops through the utilization of SDN1.

Profiling and Improvement of Grain Quality Traits for Consumer Preferable Basmati Rice in the United States

Basmati rice is a premium aromatic rice that consumers choose primarily because of its distinct aroma and excellent grain quality. The grain quality of Basmati rice (GQBR) reflects the perspectives of producers, processors, sellers, and consumers related to the production, processing, marketing, and consumption of Basmati rice. Consumers, an invaluable part of the production demand and value chain of the Basmati rice industry, have the freedom to choose from different types of aromatic rice. Consumers expect their preferred Basmati rice to possess all superior rice grain qualities, including the physical, biochemical, and physiological properties. Gene functional analysis explained that a 10-base pair deletion in the promoter region of the OsSPL16 gene causes the slender grains in Basmati rice, whereas an 8-base-pair deletion in exon 7 of the OsBadh2 gene (located in the fgr region on rice chromosome 8) results in the distinct aroma. Furthermore, a combination of the genetic characteristics of the gw8 and gs3 genes has led to the creation of a long-grain Basmati-type rice cultivar. It has also been demonstrated that agricultural, genetic, and environmental conditions significantly influence GQBR. Hence, research on improving GQBR requires a multidimensional approach and sophisticated elements due to the complexity of its nature and preference diversity. This review covers the basic definitions of grain quality traits, consumer preference criteria, influencing factors, and strategies for producing superior-quality Basmati rice in the United States. This knowledge will be useful in improving the grain quality of Basmati and Basmati-type rice, as well as developing appropriate breeding programs that will meet the preferences of different countries and cultures.

Adoption of CRISPR-Cas for crop production: present status and future prospects

Background

Global food systems in recent years have been impacted by some harsh environmental challenges and excessive anthropogenic activities. The increasing levels of both biotic and abiotic stressors have led to a decline in food production, safety, and quality. This has also contributed to a low crop production rate and difficulty in meeting the requirements of the ever-growing population. Several biotic stresses have developed above natural resistance in crops coupled with alarming contamination rates. In particular, the multiple antibiotic resistance in bacteria and some other plant pathogens has been a hot topic over recent years since the food system is often exposed to contamination at each of the farm-to-fork stages. Therefore, a system that prioritizes the safety, quality, and availability of foods is needed to meet the health and dietary preferences of everyone at every time.

Methods

This review collected scattered information on food systems and proposes methods for plant disease management. Multiple databases were searched for relevant specialized literature in the field. Particular attention was placed on the genetic methods with special interest in the potentials of the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and Cas (CRISPR associated) proteins technology in food systems and security.

Results

The review reveals the approaches that have been developed to salvage the problem of food insecurity in an attempt to achieve sustainable agriculture. On crop plants, some systems tend towards either enhancing the systemic resistance or engineering resistant varieties against known pathogens. The CRISPR-Cas technology has become a popular tool for engineering desired genes in living organisms. This review discusses its impact and why it should be considered in the sustainable management, availability, and quality of food systems. Some important roles of CRISPR-Cas have been established concerning conventional and earlier genome editing methods for simultaneous modification of different agronomic traits in crops.

Conclusion

Despite the controversies over the safety of the CRISPR-Cas system, its importance has been evident in the engineering of disease- and drought-resistant crop varieties, the improvement of crop yield, and enhancement of food quality.

An Overview of Targeted Genome Editing Strategies for Reducing the Biosynthesis of Phytic Acid: an Anti-nutrient in Crop Plants

Anti-nutrients are substances either found naturally or are of synthetic origin, which leads to the inactivation of nutrients and limits their utilization in metabolic processes. Phytic acid is classified as an anti-nutrient, as it has a strong binding affinity with most minerals like Fe, Zn, Mg, Ca, Mn, and Cd and impairs their proper metabolism. Removing anti-nutrients from cereal grains may enable the bioavailability of both macro- and micronutrients which is the desired goal of genetic engineering tools for the betterment of agronomic traits. Several strategies have been adopted to minimize phytic acid content in plants. Pursuing the molecular strategies, there are several studies, which result in the decrement of the total phytic acid content in grains of major as well as minor crops. Biosynthesis of phytic acid mainly takes place in the seed comprising lipid-dependent and lipid-independent pathways, involving various enzymes. Furthermore, some studies show that interruption of these enzymes may involve the pleiotropic effect. However, using modern biotechnological approaches, undesirable agronomic traits can be removed. This review presents an overview of different genes encoding the various enzymes involved in the biosynthetic pathway of phytic acid which is being targeted for its reduction. It also, highlights and enumerates the variety of potential applications of genome editing tools such as TALEN, ZFN, and CRISPR/Cas9 to knock out the desired genes, and RNAi for their silencing.

CRISPR/Cas9 gene editing technology: a precise and efficient tool for crop quality improvement

MAIN CONCLUSION

This review provides a direction for crop quality improvement and ideas for further research on the application of CRISPR/Cas9 gene editing technology for crop improvement. Various important crops, such as wheat, rice, soybean and tomato, are among the main sources of food and energy for humans. Breeders have long attempted to improve crop yield and quality through traditional breeding methods such as crossbreeding. However, crop breeding progress has been slow due to the limitations of traditional breeding methods. In recent years, clustered regularly spaced short palindromic repeat (CRISPR)/Cas9 gene editing technology has been continuously developed. And with the refinement of crop genome data, CRISPR/Cas9 technology has enabled significant breakthroughs in editing specific genes of crops due to its accuracy and efficiency. Precise editing of certain key genes in crops by means of CRISPR/Cas9 technology has improved crop quality and yield and has become a popular strategy for many breeders to focus on and adopt. In this paper, the present status and achievements of CRISPR/Cas9 gene technology as applied to the improvement of quality in several crops are reviewed. In addition, the shortcomings, challenges and development prospects of CRISPR/Cas9 gene editing technology are discussed.

Phytomelatonin: A key regulator of redox and phytohormones signaling against biotic/abiotic stresses

Plants being sessile in nature, are exposed to unwarranted threats as a result of constantly changing environmental conditions. These adverse factors can have negative impacts on their growth, development, and yield. Hormones are key signaling molecules enabling cells to respond rapidly to different external and internal stimuli. In plants, melatonin (MT) plays a critical role in the integration of various environmental signals and activation of stress-response networks to develop defense mechanisms and plant resilience. Additionally, melatonin can tackle the stress-induced alteration of cellular redox equilibrium by regulating the expression of redox hemostasis-related genes and proteins. The purpose of this article is to compile and summarize the scientific research pertaining to MT's effects on plants' resilience to biotic and abiotic stresses. Here, we have summarized that MT exerts a synergistic effect with other phytohormones, for instance, ethylene, jasmonic acid, and salicylic acid, and activates plant defense-related genes against phytopathogens. Furthermore, MT interacts with secondary messengers like Ca²⁺, nitric oxide, and reactive oxygen species to regulate the redox network. This interaction triggers different transcription factors to alleviate stress-related responses in plants. Hence, the critical synergic role of MT with diverse plant hormones and secondary messengers demonstrates phytomelatonin's importance in influencing multiple mechanisms to contribute to plant resilience against harsh environmental factors.

OsLPXC negatively regulates tolerance to cold stress via modulating oxidative stress, antioxidant defense and JA accumulation in rice

Exposure of crops to low temperature (LT) during emerging and reproductive stages influences their growth and development. In this study, we have isolated a cold induced, nucleus-localized lipid A gene from rice named OsLPXC, which encodes a protein of 321 amino acids. Knockout of OsLPXC resulted in enhance sensitivity to LT stress in rice, with increased accumulation of reactive oxygen species (ROS), malondialdehyde and electrolyte leakage, while expression and activities of antioxidant enzymes were significantly suppressed. The accumulation of chlorophyll content and net photosynthetic rate of knockout plants were also decreased compared with WT under LT stress. The functional analysis of differentially expressed genes (DEGs), showed that numerous genes associated with antioxidant defense, photosynthesis, cold signaling were solely expressed and downregulated in oslpxc plants compared with WT under LT. The accumulation of methyl jasmonate (MeJA) in leave and several DEGs related to the jasmonate biosynthesis pathway were significantly downregulated in OsLPXC knockout plants, which showed differential levels of MeJA regulation in WT and knockout plants in response to cold stress. These results indicated that OsLPXC positively regulates cold tolerance in rice via stabilizing the expression and activities of ROS scavenging enzymes, photosynthetic apparatus, cold signaling genes, and jasmonate biosynthesis.

Breeding and adoption of biofortified crops and their nutritional impact on human health

Micronutrient malnutrition has affected over two billion people worldwide and continues to be a health risk. A growing human population, poverty, and the prevalence of low dietary diversity are jointly responsible for malnutrition, particularly in developing nations. Inadequate bioavailability of key micronutrients, such as iron (Fe), zinc (Zn), and vitamin A, can be improved through agronomic and/or genetic interventions. The Consultative Group on International Agricultural Research prioritizes developing biofortified food crops that are rich in minerals and vitamins through the HarvestPlus initiative on biofortification. The objective of this review is to provide an overview of biofortified food crops along with evidence supporting their acceptability and adoption. Between 2004 and 2019, 242 biofortified varieties belonging to 11 major crops were released in 30 countries across Asia, Africa, and Latin America. These conventionally bred biofortified crops include Fe-enriched beans, pearl millet, and cowpea; Zn-enriched rice, wheat, and maize; both Fe- and Zn-enriched lentil and sorghum; and varieties with improved vitamin A in orange-fleshed sweet potato, maize, cassava, and banana/plantain. In addition to ongoing efforts, breeding innovations, such as speed breeding and CRISPR-based gene editing technologies, will be necessary for the next decade to reach two billion people with biofortified crops.

Bibliometric Analysis of Functional Crops and Nutritional Quality: Identification of Gene Resources to Improve Crop Nutritional Quality through Gene Editing Technology

Food security and hidden hunger are two worldwide serious and complex challenges nowadays. As one of the newly emerged technologies, gene editing technology and its application to crop improvement offers the possibility to relieve the pressure of food security and nutrient needs. In this paper, we analyzed the research status of quality improvement based on gene editing using four major crops, including rice, soybean, maize, and wheat, through a bibliometric analysis. The research hotspots now focus on the regulatory network of related traits, quite different from the technical improvements to gene editing in the early stage, while the trends in deregulation in gene-edited crops have accelerated related research. Then, we mined quality-related genes that can be edited to develop functional crops, including 16 genes related to starch, 15 to lipids, 14 to proteins, and 15 to other functional components. These findings will provide useful reference information and gene resources for the improvement of functional crops and nutritional quality based on gene editing technology.

Genome editing for vegetable crop improvement: Challenges and future prospects

Vegetable crops are known as protective foods due to their potential role in a balanced human diet, especially for vegetarians as they are a rich source of vitamins and minerals along with dietary fibers. Many biotic and abiotic stresses threaten the crop growth, yield and quality of these crops. These crops are annual, biennial and perennial in breeding behavior. Traditional breeding strategies pose many challenges in improving economic crop traits. As in most of the cases the large number of backcrosses and stringent selection pressure is required for the introgression of the useful traits into the germplasm, which is time and labour-intensive process. Plant scientists have improved economic traits like yield, quality, biotic stress resistance, abiotic stress tolerance, and improved nutritional quality of crops more precisely and accurately through the use of the revolutionary breeding method known as clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein-9 (Cas9). The high mutation efficiency, less off-target consequences and simplicity of this technique has made it possible to attain novel germplasm resources through gene-directed mutation. It facilitates mutagenic response even in complicated genomes which are difficult to breed using traditional approaches. The revelation of functions of important genes with the advancement of whole-genome sequencing has facilitated the CRISPR-Cas9 editing to mutate the desired target genes. This technology speeds up the creation of new germplasm resources having better agro-economical traits. This review entails a detailed description of CRISPR-Cas9 gene editing technology along with its potential applications in olericulture, challenges faced and future prospects.

Genetic Approaches for Iron and Zinc Biofortification and Arsenic Decrease in Oryza sativa L. Grains

Rice is the staple diet to half of the world's population, being a major source of carbohydrates, vitamins, and some essential elements. However, rice naturally contains low amounts of essential minerals such as iron (Fe) and zinc (Zn), which are drastically decreased after milling. Thus, populations that consume mostly rice may have micronutrient deficiency, which is associated with different diseases. On the other hand, rice irrigated by flooding has a high ability to accumulate arsenic (As) in the grain. Therefore, when rice is grown in areas with contaminated soil or irrigation water, it represents a risk factor for consumers, since As is associated with cancer and other diseases. Different strategies have been used to mitigate micronutrient deficiencies such as Fe and Zn and to prevent As from entering the food chain. Each strategy has its positive and its negative sides. The development of genetically biofortified rice plants with Fe and Zn and with low As accumulation is one of the most promising strategies, since it does not represent an additional cost for farmers, and gives benefits to consumers as well. Considering the importance of genetic improvement (traditional or molecular) to decrease the impact of micronutrient deficiencies such as Fe and Zn and contamination with As, this review aimed to summarize the major efforts, advances, and challenges for genetic biofortification of Fe and Zn and decrease in As content in rice grains.

CRISPR/Cas9 Technology and Its Utility for Crop Improvement

The rapid growth of the global population has resulted in a considerable increase in the demand for food crops. However, traditional crop breeding methods will not be able to satisfy the worldwide demand for food in the future. New gene-editing technologies, the most widely used of which is CRISPR/Cas9, may enable the rapid improvement of crop traits. Specifically, CRISPR/Cas9 genome-editing technology involves the use of a guide RNA and a Cas9 protein that can cleave the genome at specific loci. Due to its simplicity and efficiency, the CRISPR/Cas9 system has rapidly become the most widely used tool for editing animal and plant genomes. It is ideal for modifying the traits of many plants, including food crops, and for creating new germplasm materials. In this review, the development of the CRISPR/Cas9 system, the underlying mechanism, and examples of its use for editing genes in important crops are discussed. Furthermore, certain limitations of the CRISPR/Cas9 system and potential solutions are described. This article will provide researchers with important information regarding the use of CRISPR/Cas9 gene-editing technology for crop improvement, plant breeding, and gene functional analyses.

Applications and prospects of genome editing in plant fatty acid and triacylglycerol biosynthesis

Triacylglycerol (TAG), which is a neutral lipid, has a structure in which three molecules of fatty acid (FA) are ester-bonded to one molecule of glycerol. TAG is important energy source for seed germination and seedling development in plants. Depending on the FA composition of the TAG, it is used as an edible oil or industrial material for cosmetics, soap, and lubricant. As the demand for plant oil is rising worldwide, either the type of FA must be changed or the total oil content of various plants must be increased. In this review, we discuss the regulation of FA metabolism by Clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9, a recent genome-editing technology applicable to various plants. The development of plants with higher levels of oleic acid or lower levels of very long-chain fatty acids (VLCFAs) in seeds are discussed. In addition, the current status of research on acyltransferases, phospholipases, TAG lipases, and TAG synthesis in vegetative tissues is described. Finally, strategies for the application of CRISPR/Cas9 in lipid metabolism studies are mentioned.

CRISPR-Based Genome Editing for Nutrient Enrichment in Crops: A Promising Approach Toward Global Food Security

The global malnutrition burden imparts long-term developmental, economic, social, and medical consequences to individuals, communities, and countries. The current developments in biotechnology have infused biofortification in several food crops to fight malnutrition. However, these methods are not sustainable and suffer from several limitations, which are being solved by the CRISPR-Cas-based system of genome editing. The pin-pointed approach of CRISPR-based genome editing has made it a top-notch method due to targeted gene editing, thus making it free from ethical issues faced by transgenic crops. The CRISPR-Cas genome-editing tool has been extensively used in crop improvement programs due to its more straightforward design, low methodology cost, high efficiency, good reproducibility, and quick cycle. The system is now being utilized in the biofortification of cereal crops such as rice, wheat, barley, and maize, including vegetable crops such as potato and tomato. The CRISPR-Cas-based crop genome editing has been utilized in imparting/producing qualitative enhancement in aroma, shelf life, sweetness, and quantitative improvement in starch, protein, gamma-aminobutyric acid (GABA), oleic acid, anthocyanin, phytic acid, gluten, and steroidal glycoalkaloid contents. Some varieties have even been modified to become disease and stress-resistant. Thus, the present review critically discusses CRISPR-Cas genome editing-based biofortification of crops for imparting nutraceutical properties.

Advances in Crop Breeding Through Precision Genome Editing

The global climate change and unfavourable abiotic and biotic factors are limiting agricultural productivity and therefore intensifying the challenges for crop scientists to meet the rising demand for global food supply. The introduction of applied genetics to agriculture through plant breeding facilitated the development of hybrid varieties with improved crop productivity. However, the development of new varieties with the existing gene pools poses a challenge for crop breeders. Genetic engineering holds the potential to broaden genetic diversity by the introduction of new genes into crops. But the random insertion of foreign DNA into the plant's nuclear genome often leads to transgene silencing. Recent advances in the field of plant breeding include the development of a new breeding technique called genome editing. Genome editing technologies have emerged as powerful tools to precisely modify the crop genomes at specific sites in the genome, which has been the longstanding goal of plant breeders. The precise modification of the target genome, the absence of foreign DNA in the genome-edited plants, and the faster and cheaper method of genome modification are the remarkable features of the genome-editing technology that have resulted in its widespread application in crop breeding in less than a decade. This review focuses on the advances in crop breeding through precision genome editing. This review includes: an overview of the different breeding approaches for crop improvement; genome editing tools and their mechanism of action and application of the most widely used genome editing technology, CRISPR/Cas9, for crop improvement especially for agronomic traits such as disease resistance, abiotic stress tolerance, herbicide tolerance, yield and quality improvement, reduction of anti-nutrients, and improved shelf life; and an update on the regulatory approval of the genome-edited crops. This review also throws a light on development of high-yielding climate-resilient crops through precision genome editing.

The Interplay between Hydrogen Sulfide and Phytohormone Signaling Pathways under Challenging Environments

Hydrogen sulfide (H₂S) serves as an important gaseous signaling molecule that is involved in intra- and intercellular signal transduction in plant–environment interactions. In plants, H₂S is formed in sulfate/cysteine reduction pathways. The activation of endogenous H₂S and its exogenous application has been found to be highly effective in ameliorating a wide variety of stress conditions in plants. The H₂S interferes with the cellular redox regulatory network and prevents the degradation of proteins from oxidative stress via post-translational modifications (PTMs). H₂S-mediated persulfidation allows the rapid response of proteins in signaling networks to environmental stimuli. In addition, regulatory crosstalk of H₂S with other gaseous signals and plant growth regulators enable the activation of multiple signaling cascades that drive cellular adaptation. In this review, we summarize and discuss the current understanding of the molecular mechanisms of H₂S-induced cellular adjustments and the interactions between H₂S and various signaling pathways in plants, emphasizing the recent progress in our understanding of the effects of H₂S on the PTMs of proteins. We also discuss future directions that would advance our understanding of H₂S interactions to ultimately mitigate the impacts of environmental stresses in the plants.

Genetic Control of Seed Phytate Accumulation and the Development of Low-Phytate Crops: A Review and Perspective

Breeding low phytic acid (lpa) crops is a strategy that has potential to both improve the nutritional quality of food and feed and contribute to the sustainability of agriculture. Here, we review the lipid-independent and -dependent pathways of phytate synthesis and their regulatory mechanisms in plants. We compare the genetic variation of the phytate concentration and distribution in seeds between dicot and monocot species as well as the associated temporal and spatial expression patterns of the genes involved in phytate synthesis and transport. Quantitative trait loci or significant single nucleotide polymorphisms for the seed phytate concentration have been identified in different plant species by linkage and association mapping, and some genes have been cloned from lpa mutants. We summarize the effects of various lpa mutations on important agronomic traits in crop plants and propose SULTR3;3 and SULTR3;4 as optimal target genes for lpa crop breeding.

Genes and Their Molecular Functions Determining Seed Structure, Components, and Quality of Rice

With the improvement of people's living standards and rice trade worldwide, the demand for high-quality rice is increasing. Therefore, breeding high quality rice is critical to meet the market demand. However, progress in improving rice grain quality lags far behind that of rice yield. This might be because of the complexity of rice grain quality research, and the lack of consensus definition and evaluation standards for high quality rice. In general, the main components of rice grain quality are milling quality (MQ), appearance quality (AQ), eating and cooking quality (ECQ), and nutritional quality (NQ). Importantly, all these quality traits are determined directly or indirectly by the structure and composition of the rice seeds. Structurally, rice seeds mainly comprise the spikelet hull, seed coat, aleurone layer, embryo, and endosperm. Among them, the size of spikelet hull is the key determinant of rice grain size, which usually affects rice AQ, MQ, and ECQ. The endosperm, mainly composed of starch and protein, is the major edible part of the rice seed. Therefore, the content, constitution, and physicochemical properties of starch and protein are crucial for multiple rice grain quality traits. Moreover, the other substances, such as lipids, minerals, vitamins, and phytochemicals, included in different parts of the rice seed, also contribute significantly to rice grain quality, especially the NQ. Rice seed growth and development are precisely controlled by many genes; therefore, cloning and dissecting these quality-related genes will enhance our knowledge of rice grain quality and will assist with the breeding of high quality rice. This review focuses on summarizing the recent progress on cloning key genes and their functions in regulating rice seed structure and composition, and their corresponding contributions to rice grain quality. This information will facilitate and advance future high quality rice breeding programs.

Crop Quality Improvement Through Genome Editing Strategy

Good quality of crops has always been the most concerning aspect for breeders and consumers. However, crop quality is a complex trait affected by both the genetic systems and environmental factors, thus, it is difficult to improve through traditional breeding strategies. Recently, the CRISPR/Cas9 genome editing system, enabling efficiently targeted modification, has revolutionized the field of quality improvement in most crops. In this review, we briefly review the various genome editing ability of the CRISPR/Cas9 system, such as gene knockout, knock-in or replacement, base editing, prime editing, and gene expression regulation. In addition, we highlight the advances in crop quality improvement applying the CRISPR/Cas9 system in four main aspects: macronutrients, micronutrients, anti-nutritional factors and others. Finally, the potential challenges and future perspectives of genome editing in crop quality improvement is also discussed.

Integrating a genome-wide association study with transcriptomic data to predict candidate genes and favourable haplotypes influencing Brassica napus seed phytate

Phytate is the storage form of phosphorus in angiosperm seeds and plays vitally important roles during seed development. However, in crop plants phytate decreases bioavailability of seed-sourced mineral elements for humans, livestock and poultry, and contributes to phosphate-related water pollution. However, there is little knowledge about this trait in oilseed rape (Brassica napus). Here, a panel of 505 diverse B. napus accessions was screened in a genome-wide association study (GWAS) using 3.28 × 10⁶ single-nucleotide polymorphisms (SNPs). This identified 119 SNPs significantly associated with phytate concentration (PA_Conc) and phytate content (PA_Cont) and six candidate genes were identified. Of these, BnaA9.MRP5 represented the candidate gene for the significant SNP chrA09_5198034 (27 kb) for both PA_Cont and PA_Conc. Transcription of BnaA9.MRP5 in a low-phytate variety (LPA20) was significantly elevated compared with a high-phytate variety (HPA972). Association and haplotype analysis indicated that inbred lines carrying specific SNP haplotypes within BnaA9.MRP5 were associated with high- and low-phytate phenotypes. No significant differences in seed germination and seed yield were detected between low and high phytate cultivars examined. Candidate genes, favourable haplotypes and the low phytate varieties identified in this study will be useful for low-phytate breeding of B. napus.

Genome editing in cereal crops: an overview

Genome-editing technologies offer unprecedented opportunities for crop improvement with superior precision and speed. This review presents an analysis of the current state of genome editing in the major cereal crops- rice, maize, wheat and barley. Genome editing has been used to achieve important agronomic and quality traits in cereals. These include adaptive traits to mitigate the effects of climate change, tolerance to biotic stresses, higher yields, more optimal plant architecture, improved grain quality and nutritional content, and safer products. Not all traits can be achieved through genome editing, and several technical and regulatory challenges need to be overcome for the technology to realize its full potential. Genome editing, however, has already revolutionized cereal crop improvement and is poised to shape future agricultural practices in conjunction with other breeding innovations.

Plant phospholipase D: novel structure, regulatory mechanism, and multifaceted functions with biotechnological application

Phospholipases D (PLDs) are important membrane lipid-modifying enzymes in eukaryotes. Phosphatidic acid, the product of PLD activity, is a vital signaling molecule. PLD-mediated lipid signaling has been the subject of extensive research leading to discovery of its crystal structure. PLDs are involved in the pathophysiology of several human diseases, therefore, viewed as promising targets for drug design. The availability of a eukaryotic PLD crystal structure will encourage PLD targeted drug designing. PLDs have been implicated in plants response to biotic and abiotic stresses. However, the molecular mechanism of response is not clear. Recently, several novel findings have shown that PLD mediated modulation of structural and developmental processes, such as: stomata movement, root growth and microtubule organization are crucial for plants adaptation to environmental stresses. Involvement of PLDs in regulating membrane remodeling, auxin mediated alteration of root system architecture and nutrient uptake to combat nitrogen and phosphorus deficiencies and magnesium toxicity is established. PLDs via vesicle trafficking modulate cytoskeleton and exocytosis to regulate self-incompatibility (SI) signaling in flowering plants, thereby contributes to plants hybrid vigor and diversity. In addition, the important role of PLDs has been recognized in biotechnologically important functions, including oil/TAG synthesis and maintenance of seed quality. In this review, we describe the crystal structure of a plant PLD and discuss the molecular mechanism of catalysis and activity regulation. Further, the role of PLDs in regulating plant development under biotic and abiotic stresses, nitrogen and phosphorus deficiency, magnesium ion toxicity, SI signaling and pollen tube growth and in important biotechnological applications has been discussed.

CRISPR/Cas systems: opportunities and challenges for crop breeding

Increasing crop production to meet the demands of a growing population depends largely on crop improvement through new plant-breeding techniques (NPBT) such as genome editing. CRISPR/Cas systems are NPBTs that enable efficient target-specific gene editing in crops, which is supposed to accelerate crop breeding in a way that is different from genetically modified (GM) technology. Herein, we review the applications of CRISPR/Cas systems in crop breeding focusing on crop domestication, heterosis, haploid induction, and synthetic biology, and summarize the screening methods of CRISPR/Cas-induced mutations in crops. We highlight the importance of molecular characterization of CRISPR/Cas-edited crops, and pay special attentions to emerging highly specific genome-editing tools such as base editors and prime editors. We also discuss future improvements of CRISPR/Cas systems for crop improvement.

Application of CRISPR/Cas9 in Crop Quality Improvement

The various crop species are major agricultural products and play an indispensable role in sustaining human life. Over a long period, breeders strove to increase crop yield and improve quality through traditional breeding strategies. Today, many breeders have achieved remarkable results using modern molecular technologies. Recently, a new gene-editing system, named the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 technology, has also succeeded in improving crop quality. It has become the most popular tool for crop improvement due to its versatility. It has accelerated crop breeding progress by virtue of its precision in specific gene editing. This review summarizes the current application of CRISPR/Cas9 technology in crop quality improvement. It includes the modulation in appearance, palatability, nutritional components and other preferred traits of various crops. In addition, the challenge in its future application is also discussed.

The evolution and history of gene editing technologies

Scientific enquiry must be the driving force of research. This sentiment is manifested as the profound impact gene editing technologies are having in our current world. There exist three main gene editing technologies today: Zinc Finger Nucleases, TALENs and the CRISPR-Cas system. When these systems were being uncovered, none of the scientists set out to design tools to engineer genomes. They were simply trying to understand the mechanisms existing in nature. If it was not for this simple sense of wonder, we probably would not have these breakthrough technologies. In this chapter, we will discuss the history, applications and ethical issues surrounding these technologies, focusing on the now predominant CRISPR-Cas technology. Gene editing technologies, as we know them now, are poised to have an overwhelming impact on our world. However, it is impossible to predict the route they will take in the future or to comprehend the full impact of its repercussions.

Applications of CRISPR-Cas in agriculture and plant biotechnology

The prokaryote-derived CRISPR-Cas genome editing technology has altered plant molecular biology beyond all expectations. Characterized by robustness and high target specificity and programmability, CRISPR-Cas allows precise genetic manipulation of crop species, which provides the opportunity to create germplasms with beneficial traits and to develop novel, more sustainable agricultural systems. Furthermore, the numerous emerging biotechnologies based on CRISPR-Cas platforms have expanded the toolbox of fundamental research and plant synthetic biology. In this Review, we first briefly describe gene editing by CRISPR-Cas, focusing on the newest, precise gene editing technologies such as base editing and prime editing. We then discuss the most important applications of CRISPR-Cas in increasing plant yield, quality, disease resistance and herbicide resistance, breeding and accelerated domestication. We also highlight the most recent breakthroughs in CRISPR-Cas-related plant biotechnologies, including CRISPR-Cas reagent delivery, gene regulation, multiplexed gene editing and mutagenesis and directed evolution technologies. Finally, we discuss prospective applications of this game-changing technology.

Mutations of OsPLDa1 Increase Lysophospholipid Content and Enhance Cooking and Eating Quality in Rice

Phospholipids belong to a significant class of lipids and comprise ~10% of total lipids in rice grains. Lysophospholipid (LPL) is derived from the hydrolysis of phospholipids and plays an important role in rice grain quality. Our previous study demonstrated that mutations in a phospholipase D gene (OsPLDα1) significantly altered lipid metabolites and reduced phytic acid content. In the present study, the effect of two ospldα1 mutations on LPL and other physicochemical prosperities of brown rice was further investigated, with the aim of assessing the overall importance of ospldα1 mutations in rice grain quality. Metabolite profiling revealed a ~15% increase in LPL level in both ospldα1 mutants as compared with their wild-type (WT) parent. Both ospldα1 mutations significantly lowered the apparent amylose content in brown rice flour (~1.9%) and altered viscosity profiles with significantly increased breakdown (+12.4%) and significantly reduced setback viscosity (−6.2%). Moreover, both ospldα1 mutations significantly lowered the gelatinization onset, peak temperature and retrogradation percentage of brown rice flour. This study demonstrated that OsPLDα1 plays a crucial role in rice grain quality and its mutation could, in general, improve the cooking and eating quality and nourishment of brown rice.

Knockout of MULTI-DRUG RESISTANT PROTEIN 5 Genes Lead to Low Phytic Acid Contents in Oilseed Rape

Understanding phosphate uptake and storage is interesting to optimize the plant performance to phosphorus fluctuations. Phytic acid (PA) is the major source of inorganic phosphorus (Pi) in plants. Genetic analyses of PA pathway transporter genes (BnMRP5) and their functional characterization might provide clues in better utilizing the available phosphate resources. Furthermore, the failure to assimilate PA by monogastric animals results in its excess accumulation in manure, which ultimately causes groundwater eutrophication. As a first step toward breeding low PA mutants in oilseed rape (Brassica napus L.), we identified knockout mutants in PA biosynthesis and transporter genes. The obtained M₃ single mutants of Bn.MRP5.A10 and Bn.MRP5.C09 were combined by crossing to produce double mutants. Simultaneously, crosses were performed with the non-mutagenized EMS donor genotype to reduce the background mutation load. Double mutants identified from the F₂ progeny of direct M₃ crosses and BC₁ plants showed 15% reduction in PA contents with no significant differences in Pi. We are discussing the function of BnMRP5 paralogs and the benefits for breeding Bnmrp5 mutants in respect to low PA, yield, and stress tolerances.