CRISPR-mediated accelerated domestication of African rice landraces

Strong culm: a crucial trait for developing next-generation climate-resilient rice lines

Lodging, a phenomenon characterized by the bending or breaking of rice plants, poses substantial constraints on productivity, particularly during the harvesting phase in regions susceptible to strong winds. The rice strong culm trait is influenced by the intricate interplay of genetic, physiological, epigenetic, and environmental factors. Stem architecture, encompassing morphological and anatomical attributes, alongside the composition of both structural and non-structural carbohydrates, emerges as a critical determinant of lodging resistance. The adaptive response of the rice culm to various biotic and abiotic environmental factors further modulates the propensity for lodging. Advancements in next-generation sequencing technologies have expedited the genetic dissection of lodging resistance, enabling the identification of pertinent genes, quantitative trait loci, and novel alleles. Concurrently, contemporary breeding strategies, ranging from biparental approaches to more sophisticated methods such as multi-parent-based breeding, gene pyramiding, genomic selection, genome-wide association studies, and haplotype-based breeding, offer perspectives on the genetic underpinnings of culm strength. This review comprehensively delves into physiological attributes, culm histology, epigenetic determinants, and gene expression profiles associated with lodging resistance, with a specialized focus on leveraging next-generation sequencing for candidate gene discovery.

CRISPR enables sustainable cereal production for a greener future

The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system has become the most important tool for targeted genome editing in many plant and animal species over the past decade. The CRISPR/Cas9 technology has also sparked a flood of applications and technical advancements in genome editing in the key cereal crops, including rice, wheat, maize, and barley. Here, we review advanced uses of CRISPR/Cas9 and derived systems in genome editing of cereal crops to enhance a variety of agronomically important features. We also highlight new technological advances for delivering preassembled Cas9-gRNA ribonucleoprotein (RNP)-editing systems, multiplex editing, gain-of-function strategies, the use of artificial intelligence (AI)-based tools, and combining CRISPR with novel speed breeding (SB) and vernalization strategies.

Integrative and inclusive genomics to promote the use of underutilised crops

Underutilised crops or orphan crops are important for diversifying our food systems towards food and nutrition security. Here, the authors discuss how the development of underutilised crop genomic resource should align with their breeding and capacity building strategies, and leverage advances made in major crops.

GRASSY TILLERS1 (GT1) and SIX-ROWED SPIKE1 (VRS1) homologs share conserved roles in growth repression

Crop engineering and de novo domestication using gene editing are new frontiers in agriculture. However, outside of well-studied crops and model systems, prioritizing engineering targets remains challenging. Evolution can guide us, revealing genes with deeply conserved roles that have repeatedly been selected in the evolution of plant form. Homologs of the transcription factor genes GRASSY TILLERS1 (GT1) and SIX-ROWED SPIKE1 (VRS1) have repeatedly been targets of selection in domestication and evolution, where they repress growth in many developmental contexts. This suggests a conserved role for these genes in regulating growth repression. To test this, we determined the roles of GT1 and VRS1 homologs in maize (Zea mays) and the distantly related grass brachypodium (Brachypodium distachyon) using gene editing and mutant analysis. In maize, gt1; vrs1-like1 (vrl1) mutants have derepressed growth of floral organs. In addition, gt1; vrl1 mutants bore more ears and more branches, indicating broad roles in growth repression. In brachypodium, Bdgt1; Bdvrl1 mutants have more branches, spikelets, and flowers than wild-type plants, indicating conserved roles for GT1 and VRS1 homologs in growth suppression over ca. 59 My of grass evolution. Importantly, many of these traits influence crop productivity. Notably, maize GT1 can suppress growth in arabidopsis (Arabidopsis thaliana) floral organs, despite ca. 160 My of evolution separating the grasses and arabidopsis. Thus, GT1 and VRS1 maintain their potency as growth regulators across vast timescales and in distinct developmental contexts. This work highlights the power of evolution to inform gene editing in crop improvement.

Molecular basis of genetic improvement for key rice quality traits in Southern China

Grain qualities including milling quality, appearance quality, eating and cooking quality, and nutritional quality are important indicators in rice breeding. Significant achievements in genetic improvement of rice quality have been made. In this study, we analyzed the variation patterns of 16 traits in 1570 rice varieties and found significant improvements in appearance quality and eating and cooking quality, particularly in hybrid rice. Through genome-wide association study and allelic functional nucleotide polymorphisms analysis of quality trait genes, we found that ALK, FGR1, FLO7, GL7/GW7, GLW7, GS2, GS3, ONAC129, OsGRF8, POW1, WCR1, and Wx were associated with the genetic improvement of rice quality traits in Southern China. Allelic functional nucleotide polymorphisms analysis of 13 important rice quality genes, including fragrance gene fgr, were performed using the polymerase chain reaction amplification refractory mutation system technology. The results showed that Gui516, Gui569, Gui721, Ryousi, Rsimiao, Rbasi, and Yuehui9802 possessed multiple superior alleles. This study elucidates the phenotypic changes and molecular basis of key quality traits of varieties in Southern China. The findings will provide guidance for genetic improvement of rice quality and the development of new varieties.

Multi-faceted CRISPR-Cas9 strategy to reduce plant based food loss and waste for sustainable bio-economy - A review

Currently, international development requires innovative solutions to address imminent challenges like climate change, unsustainable food system, food waste, energy crisis, and environmental degradation. All the same, addressing these concerns with conventional technologies is time-consuming, causes harmful environmental impacts, and is not cost-effective. Thus, biotechnological tools become imperative for enhancing food and energy resilience through eco-friendly bio-based products by valorisation of plant and food waste to meet the goals of circular bioeconomy in conjunction with Sustainable Developmental Goals (SDGs). Genome editing can be accomplished using a revolutionary DNA modification tool, CRISPR-Cas9, through its uncomplicated guided mechanism, with great efficiency in various organisms targeting different traits. This review's main objective is to examine how the CRISPR-Cas system, which has positive features, could improve the bioeconomy by reducing food loss and waste with all-inclusive food supply chain both at on-farm and off-farm level; utilising food loss and waste by genome edited microorganisms through food valorisation; efficient microbial conversion of low-cost substrates as biofuel; valorisation of agro-industrial wastes; mitigating greenhouse gas emissions through forestry plantation crops; and protecting the ecosystem and environment. Finally, the ethical implications and regulatory issues that are related to CRISPR-Cas edited products in the international markets have also been taken into consideration.

The ALOG family members OsG1L1 and OsG1L2 regulate inflorescence branching in rice

The architecture of the rice inflorescence is an important determinant of crop yield. The length of the inflorescence and the number of branches are among the key factors determining the number of spikelets, and thus grains, that a plant will develop. In particular, the timing of the identity transition from indeterminate branch meristem to determinate spikelet meristem governs the complexity of the inflorescence. In this context, the ALOG gene TAWAWA1 (TAW1) has been shown to delay the transition to determinate spikelet development in Oryza sativa (rice). Recently, by combining precise laser microdissection of inflorescence meristems with RNA-seq, we observed that two ALOG genes, OsG1-like 1 (OsG1L1) and OsG1L2, have expression profiles similar to that of TAW1. Here, we report that osg1l1 and osg1l2 loss-of-function CRISPR mutants have similar phenotypes to the phenotype of the previously published taw1 mutant, suggesting that these genes might act on related pathways during inflorescence development. Transcriptome analysis of the osg1l2 mutant suggested interactions of OsG1L2 with other known inflorescence architecture regulators and the data sets were used for the construction of a gene regulatory network (GRN), proposing interactions among genes potentially involved in controlling inflorescence development in rice. In this GRN, we selected the homeodomain-leucine zipper transcription factor encoding the gene OsHOX14 for further characterization. The spatiotemporal expression profiling and phenotypical analysis of CRISPR loss-of-function mutants of OsHOX14 suggests that the proposed GRN indeed serves as a valuable resource for the identification of new proteins involved in rice inflorescence development.

CRISPRa-mediated transcriptional activation of the SlPR-1 gene in edited tomato plants

With the continuous deterioration of arable land due to an ever-growing population, improvement of crops and crop protection have a fundamental role in maintaining and increasing crop productivity. Alternatives to the use of pesticides encompass the use of biological control agents, generation of new resistant crop cultivars, the application of plant activator agrochemicals to enhance plant defenses, and the use of gene editing techniques, like the CRISPR-Cas system. Here, we test the hypothesis that epigenome editing, via CRISPR activation (CRISPRa), activate tomato plant defense genes to confer resistance against pathogen attack. We provide evidence that edited tomato plants for the PATHOGENESIS-RELATED GENE 1 gene (SlPR-1) show enhanced disease resistance to Clavibacter michiganensis subsp. michiganensis infection. Resistance was assessed by evaluating disease progression and symptom appearance, pathogen accumulation, and changes in SlPR-1 gene expression at different time points. We determined that CRISPRa-edited plants develop enhanced disease-resistant to the pathogen without altering their agronomic characteristics and, above all, preventing the advancement of disease symptoms, stem canker, and plant death.

Clustered regularly interspaced short palindromic repeats tools for plant metabolic engineering: achievements and perspectives

The plant kingdom represents the biggest source of feedstock, food, and added-value compounds. Engineering plant metabolic pathways to increase the phytochemical production or improve the nutraceutical value of crops is challenging because of the intricate interaction networks that link multiple genes, enzymatic steps, and metabolites, even when pathways are fully elucidated. The development of clustered regularly interspaced short palindromic repeats - CRISPR-associated (CRISPR-Cas) technologies has helped to overcome limitations in metabolic engineering, providing efficient and versatile tools for multigene editing. CRISPR approaches in plants were shown to have a remarkable efficiency in genome editing of different species to improve agronomic and metabolic traits. Here, we give an overview of the different achievements and perspectives of CRISPR technology in plant metabolic engineering.

CRISPR technology: A decade of genome editing is only the beginning

The advent of clustered regularly interspaced short palindromic repeat (CRISPR) genome editing, coupled with advances in computing and imaging capabilities, has initiated a new era in which genetic diseases and individual disease susceptibilities are both predictable and actionable. Likewise, genes responsible for plant traits can be identified and altered quickly, transforming the pace of agricultural research and plant breeding. In this Review, we discuss the current state of CRISPR-mediated genetic manipulation in human cells, animals, and plants along with relevant successes and challenges and present a roadmap for the future of this technology.

Genetic manipulation of photosynthesis to enhance crop productivity under changing environmental conditions

Current global agricultural production needs to be increased to feed the unconstrained growing population. The changing climatic condition due to anthropogenic activities also makes the conditions more challenging to meet the required crop productivity in the future. The increase in crop productivity in the post green revolution era most likely became stagnant, or no major enhancement in crop productivity observed. In this review article, we discuss the emerging approaches for the enhancement of crop production along with dealing to the future climate changes like rise in temperature, increase in precipitation and decrease in snow and ice level, etc. At first, we discuss the efforts made for the genetic manipulation of chlorophyll metabolism, antenna engineering, electron transport chain, carbon fixation, and photorespiratory processes to enhance the photosynthesis of plants and to develop tolerance in plants to cope with changing environmental conditions. The application of CRISPR to enhance the crop productivity and develop abiotic stress-tolerant plants to face the current changing climatic conditions is also discussed.

Improving environmental stress resilience in crops by genome editing: insights from extremophile plants

In basic and applied sciences, genome editing has become an indispensable tool, especially the versatile and adaptable CRISPR/Cas9 system. Using CRISPR/Cas9 in plants has enabled modifications of many valuable traits, including environmental stress tolerance, an essential aspect when it comes to ensuring food security under climate change pressure. The CRISPR toolbox enables faster and more precise plant breeding by facilitating: multiplex gene editing, gene pyramiding, and de novo domestication. In this paper, we discuss the most recent advances in CRISPR/Cas9 and alternative CRISPR-based systems, along with the technical challenges that remain to be overcome. A revision of the latest proof-of-concept and functional characterization studies has indeed provided more insight into the quantitative traits affecting crop yield and stress tolerance. Additionally, we focus on the applications of CRISPR/Cas9 technology in regard to extremophile plants, due to their significance on: industrial, ecological and economic levels. These still unexplored genetic resources could provide the means to harden our crops against the threat of climate change, thus ensuring food security over the next century.

Genome Editing-accelerated Re-Domestication (GEaReD) - a new major direction in plant breeding

BACKGROUND

The effects of climate change, soil depletion, a growing world population putting pressure on food safety and security are major challenges for agriculture in the 21st century. The breeding success of the green revolution has decelerated and current programs can only offset the yield affecting factors.

PURPOSE AND SCOPE

New approaches are urgently needed and we propose "Genome Editing-accelerated Re-Domestication" (GEaReD) as a major new direction in plant breeding. By combining the upcoming technologies for phenotyping, omics, and artificial intelligence with the promising new CRISPR-toolkits, this approach is closer than ever.

SUMMARY AND CONCLUSION

Wild relatives of current crops are often adapted to harsh environments and have a high genetic diversity. Redomestication of wild barley or teosinte could generate new cultivars adapted to environmental changes. De novo domestication of perennial relatives such as Hordeum bulbosum could counter soil depletion and increase soil carbon. Recent research already proved the principle of redomestication in tomato and rice and therefore laid the foundation for GEaReD. This article is protected by copyright. All rights reserved.

RLB (RICE LATERAL BRANCH) recruits PRC2-mediated H3K27 tri-methylation on OsCKX4 to regulate lateral branching

Lateral branches such as shoot and panicle are determining factors and target traits for rice (Oryza sativa L.) yield improvement. Cytokinin promotes rice lateral branching; however, the mechanism underlying the fine-tuning of cytokinin homeostasis in rice branching remains largely unknown. Here, we report the map-based cloning of RICE LATERAL BRANCH (RLB) encoding a nuclear-localized, KNOX-type homeobox protein from a rice cytokinin-deficient mutant showing more tillers, sparser panicles, defected floret morphology as well as attenuated shoot regeneration from callus. RLB directly binds to the promoter and represses the transcription of OsCKX4, a cytokinin oxidase gene with high abundance in panicle branch meristem. OsCKX4 over-expression lines phenocopied rlb, which showed upregulated OsCKX4 levels. Meanwhile, RLB physically binds to Polycomb repressive complex 2 (PRC2) components OsEMF2b and co-localized with H3K27me3, a suppressing histone modification mediated by PRC2, in the OsCKX4 promoter. We proposed that RLB recruits PRC2 to the OsCKX4 promoter to epigenetically repress its transcription, which suppresses the catabolism of cytokinin, thereby promoting rice lateral branching. Moreover, antisense inhibition of OsCKX4 under the LOG promoter successfully increased panicle size and spikelet number per plant without affecting other major agronomic traits. This study provides insight into cytokinin homeostasis, lateral branching in plants, and also promising target genes for rice genetic improvement.

Multiplex Genome-Editing Technologies for Revolutionizing Plant Biology and Crop Improvement

Multiplex genome-editing (MGE) technologies are recently developed versatile bioengineering tools for modifying two or more specific DNA loci in a genome with high precision. These genome-editing tools have greatly increased the feasibility of introducing desired changes at multiple nucleotide levels into a target genome. In particular, clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) [CRISPR/Cas] system-based MGE tools allow the simultaneous generation of direct mutations precisely at multiple loci in a gene or multiple genes. MGE is enhancing the field of plant molecular biology and providing capabilities for revolutionizing modern crop-breeding methods as it was virtually impossible to edit genomes so precisely at the single base-pair level with prior genome-editing tools, such as zinc-finger nucleases (ZFNs) and transcription activator-like effector nucleases (TALENs). Recently, researchers have not only started using MGE tools to advance genome-editing applications in certain plant science fields but also have attempted to decipher and answer basic questions related to plant biology. In this review, we discuss the current progress that has been made toward the development and utilization of MGE tools with an emphasis on the improvements in plant biology after the discovery of CRISPR/Cas9. Furthermore, the most recent advancements involving CRISPR/Cas applications for editing multiple loci or genes are described. Finally, insights into the strengths and importance of MGE technology in advancing crop-improvement programs are presented.

Current Advancements and Limitations of Gene Editing in Orphan Crops

Gene editing provides precise, heritable genome mutagenesis without permanent transgenesis, and has been widely demonstrated and applied in planta. In the past decade, clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated proteins (Cas) has revolutionized the application of gene editing in crops, with mechanistic advances expanding its potential, including prime editing and base editing. To date, CRISPR/Cas has been utilized in over a dozen orphan crops with diverse genetic backgrounds, leading to novel alleles and beneficial phenotypes for breeders, growers, and consumers. In conjunction with the adoption of science-based regulatory practices, there is potential for CRISPR/Cas-mediated gene editing in orphan crop improvement programs to solve a plethora of agricultural problems, especially impacting developing countries. Genome sequencing has progressed, becoming more affordable and applicable to orphan crops. Open-access resources allow for target gene identification and guide RNA (gRNA) design and evaluation, with modular cloning systems and enzyme screening methods providing experimental feasibility. While the genomic and mechanistic limitations are being overcome, crop transformation and regeneration continue to be the bottleneck for gene editing applications. International collaboration between all stakeholders involved in crop improvement is vital to provide equitable access and bridge the scientific gap between the world's most economically important crops and the most under-researched crops. This review describes the mechanisms and workflow of CRISPR/Cas in planta and addresses the challenges, current applications, and future prospects in orphan crops.

Application of Gene Editing for Climate Change in Agriculture

Climate change imposes a severe threat to agricultural systems, food security, and human nutrition. Meanwhile, efforts in crop and livestock gene editing have been undertaken to improve performance across a range of traits. Many of the targeted phenotypes include attributes that could be beneficial for climate change adaptation. Here, we present examples of emerging gene editing applications and research initiatives that are aimed at the improvement of crops and livestock in response to climate change, and discuss technical limitations and opportunities therein. While only few applications of gene editing have been translated to agricultural production thus far, numerous studies in research settings have demonstrated the potential for potent applications to address climate change in the near future.

CRISPR-Based Crop Improvements: A Way Forward to Achieve Zero Hunger

Zero hunger is one of the sustainable development goals set by the United Nations in 2015 to achieve global food security by 2030. The current harvest of crops is insufficient; feeding the world's population and meeting the goal of zero hunger by 2030 will require larger and more consistent crop production. Clustered regularly interspaced short palindromic repeats-associated protein (CRISPR-Cas) technology is widely used for the plant genome editing. In this review, we consider this technology as a potential tool for achieving zero hunger. We provide a comprehensive overview of CRISPR-Cas technology and its most important applications for food crops' improvement. We also conferred current and potential technological breakthroughs that will help in breeding future crops to end global hunger. The regulatory aspects of deploying this technology in commercial sectors, bioethics, and the production of transgene-free plants are also discussed. We hope that the CRISPR-Cas system will accelerate the breeding of improved crop cultivars compared with conventional breeding and pave the way toward the zero hunger goal.

OMICs, Epigenetics, and Genome Editing Techniques for Food and Nutritional Security

The incredible success of crop breeding and agricultural innovation in the last century greatly contributed to the Green Revolution, which significantly increased yields and ensures food security, despite the population explosion. However, new challenges such as rapid climate change, deteriorating soil, and the accumulation of pollutants require much faster responses and more effective solutions that cannot be achieved through traditional breeding. Further prospects for increasing the efficiency of agriculture are undoubtedly associated with the inclusion in the breeding strategy of new knowledge obtained using high-throughput technologies and new tools in the future to ensure the design of new plant genomes and predict the desired phenotype. This article provides an overview of the current state of research in these areas, as well as the study of soil and plant microbiomes, and the prospective use of their potential in a new field of microbiome engineering. In terms of genomic and phenomic predictions, we also propose an integrated approach that combines high-density genotyping and high-throughput phenotyping techniques, which can improve the prediction accuracy of quantitative traits in crop species.

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.

Novel QTL Associated with Shoot Branching Identified in Doubled Haploid Rice (Oryza sativa L.) under Low Nitrogen Cultivation

Shoot branching is considered as an important trait for the architecture of plants and contributes to their growth and productivity. In cereal crops, such as rice, shoot branching is controlled by many factors, including phytohormones signaling networks, operating either in synergy or antagonizing each other. In rice, shoot branching indicates the ability to produce more tillers that are essential for achieving high productivity and yield potential. In the present study, we evaluated the growth and development, and yield components of a doubled haploid population derived from a cross between 93-11 (P1, indica) and Milyang352 (P2, japonica), grown under normal nitrogen and low nitrogen cultivation open field conditions. The results of the phenotypic evaluation indicated that parental lines 93-11 (P1, a high tillering indica cultivar) and Milyang352 (P2, a low tillering japonica cultivar) showed distinctive phenotypic responses, also reflected in their derived population. In addition, the linkage mapping and quantitative trait locus (QTL) analysis detected three QTLs associated with tiller number on chromosome 2 (qTNN2-1, 130 cM, logarithm of the odds (LOD) 4.14, PVE 14.5%; and qTNL2-1, 134 cM, LOD: 6.05, PVE: 20.5%) and chromosome 4 (qTN4-1, 134 cM, LOD 3.92, PVE 14.5%), with qTNL2-1 having the highest phenotypic variation explained, and the only QTL associated with tiller number under low nitrogen cultivation conditions, using Kompetitive Allele-Specific PCR (KASP) and Fluidigm markers. The additive effect (1.81) of qTNL2-1 indicates that the allele from 93-11 (P1) contributed to the observed phenotypic variation for tiller number under low nitrogen cultivation. The breakthrough is that the majority of the candidate genes harbored by the QTLs qTNL2-1 and qTNN4-1 (here associated with the control of shoot branching under low and normal nitrogen cultivation, respectively), were also proposed to be involved in plant stress signaling or response mechanisms, with regard to their annotations and previous reports. Therefore, put together, these results would suggest that a possible crosstalk exists between the control of plant growth and development and the stress response in rice.

Understanding Omics Driven Plant Improvement and de novo Crop Domestication: Some Examples

In the current era, one of biggest challenges is to shorten the breeding cycle for rapid generation of a new crop variety having high yield capacity, disease resistance, high nutrient content, etc. Advances in the "-omics" technology have revolutionized the discovery of genes and bio-molecules with remarkable precision, resulting in significant development of plant-focused metabolic databases and resources. Metabolomics has been widely used in several model plants and crop species to examine metabolic drift and changes in metabolic composition during various developmental stages and in response to stimuli. Over the last few decades, these efforts have resulted in a significantly improved understanding of the metabolic pathways of plants through identification of several unknown intermediates. This has assisted in developing several new metabolically engineered important crops with desirable agronomic traits, and has facilitated the de novo domestication of new crops for sustainable agriculture and food security. In this review, we discuss how "omics" technologies, particularly metabolomics, has enhanced our understanding of important traits and allowed speedy domestication of novel crop plants.

A route to de novo domestication of wild allotetraploid rice

Cultivated rice varieties are all diploid, and polyploidization of rice has long been desired because of its advantages in genome buffering, vigorousness, and environmental robustness. However, a workable route remains elusive. Here, we describe a practical strategy, namely de novo domestication of wild allotetraploid rice. By screening allotetraploid wild rice inventory, we identified one genotype of Oryza alta (CCDD), polyploid rice 1 (PPR1), and established two important resources for its de novo domestication: (1) an efficient tissue culture, transformation, and genome editing system and (2) a high-quality genome assembly discriminated into two subgenomes of 12 chromosomes apiece. With these resources, we show that six agronomically important traits could be rapidly improved by editing O. alta homologs of the genes controlling these traits in diploid rice. Our results demonstrate the possibility that de novo domesticated allotetraploid rice can be developed into a new staple cereal to strengthen world food security.

Transgenic rice Oryza glaberrima with higher CPD photolyase activity alleviates UVB-caused growth inhibition

The ultraviolet B (UVB) sensitivity of rice cultivated in Asia and Africa varies greatly, with African rice cultivars (Oryza glaberrima Steud. and O. barthii A. Chev.) being more sensitive to UVB because of their low cyclobutane pyrimidine dimer (CPD) photolyase activity, which is a CPD repair enzyme, relative to Asian rice cultivars (O. sativa L.). Hence, the production of UVB-resistant African rice with augmented CPD photolyase activity is of great importance, although difficulty in transforming the African rice cultivars to this end has been reported. Here, we successfully produced overexpressing transgenic African rice with higher CPD photolyase activity by modifying media conditions for callus induction and regeneration using the parental line (PL), UVB-sensitive African rice TOG12380 (O. glaberrima). The overexpressing transgenic African rice carried a single copy of the CPD photolyase enzyme, with a 4.4-fold higher level of CPD photolyase transcripts and 2.6-fold higher activity than its PL counterpart. When the plants were grown for 21 days in a growth chamber under visible radiation or with supplementary various UVB radiation, the overexpressing transgenic plants have a significantly increased UVB resistance index compared to PL plants. These results strongly suggest that CPD photolyase remains an essential factor for tolerating UVB radiation stress in African rice. As a result, African rice cultivars with overexpressed CPD photolyase may survive better in tropical areas more prone to UVB radiation stress, including Africa. Collectively, our results provide strong evidence that CPD photolyase is a useful biotechnological tool for reducing UVB-induced growth inhibition in African rice crops of O. glaberrima.

Genetically modified organisms and food security in Southern Africa: conundrum and discourse

The importance of food security and nourishment is recognized in Southern African region and in many communities, globally. However, the attainment of food security in Southern African countries is affected by many factors, including adverse environmental conditions, pests and diseases. Scientists have been insistently looking for innovative strategies to optimize crop production and combat challenges militating against attainment of food security. In agriculture, strategies of increasing crop production include but not limited to improved crop varieties, farming practices, extension services, irrigation services, mechanization, information technology, use of fertilizers and agrochemicals. Equally important is genetic modification (GM) technology, which brings new prospects in addressing food security problems. Nonetheless, since the introduction of genetically modified crops (GMOs) three decades ago, it has been a topic of public discourse across the globe, conspicuously so in Southern African region. This is regardless of the evidence that planting GMOs positively influenced farmer’s incomes, economic access to food and increased tolerance of crops to various biotic and abiotic stresses. This paper looks at the issues surrounding GMOs adoption in Southern Africa and lack thereof, the discourse, and its potential in contributing to the attainment of food security for the present as well as future generations.