Gene Editing Technology: An Opportunity for a Food Secured Nigeria
Abraham Isah Rose S.M. Gidado
May 2019
Figure 1: Strategies used in genome editing of plants and animals
Source: Ho et al. (2018)
Genetic manipulation of metabolic pathways in crops in a highly targeted manner have been made possible through the significant scientific revolution made in the fields of molecular biology and plant genetics during the last quarter of the 20th century. Taking Nigeria’s first genetically modified (GM) food crop, GM Cowpea, for an instance, with a trait capable to ward off the deadly maruca insects, this wouldn’t have been possible using the conventional breeding technique as more than fifteen thousand accessions have been tested before now. Though GM crop varieties with new traits and enhanced characteristics have been produced, in some cases, commercialized throughout the world, they have usually been associated with generally unproven and sentimental concerns over health and environmental safety, which often elevates into political issues. Over the last eight years, a series of new Gene Editing Technologies have become fashionable because they are able to knock-out or modify specific targeted gene sequence. Nigeria is looking ready to take full advantage of this technology in tackling food insecurity and diseases as the Nation’s 8th National Assembly declared a one-day public hearing on “a bill for an act to amend the National Biosafety Management Agency Act 2015, to enlarge the scope of the application and include other evolving aspect of the application of modern biotechnology in Nigeria (Hb. 1578)” on 27th March, 2019 during which the gene editing technology was extensively discussed.
An example of genome-editing technologies is the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR). The CRISPR/Cas9 has lately moved to the vanguard of the Genome Editing Technologies for plants because of its high precision and simplicity. In addition, it is quicker and easier to use with fewer intellectual property restrictions. This efficient gene editing system will reduce many of the opinion gaps that have contributed to the opposition of the genetic modification technology. The principle of gene editing technology is grounded on chimeric proteins (proteins made from combination of two different genes) made up of sequence-specific DNA binding domains and non-specific DNA cleavage nucleases.
Unknown to plant traditional breeders, they have long been practicing the science of gene editing. The science of crossing different plants and selective breeding has long been practiced by traditional plant breeders for several century. Line crossing, gene recombination and wide crosses with wild species which normally would not have crossed at all were some of the techniques engaged by traditional breeders. The end results of these processes are introduction of individual genes like those conferring traits such as stress tolerance from a particularly tolerant wild relative. Gene editing technology is an unadventurous method that modifies the genotype and phenotype of a plant or animal. The two methods that are typically adopted for gene function analysis include: traditional forward genetics method (changes from phenotypic to genotypic traits) which uses T-DNA tag or map-based cloning to allow the identification of new functional genes and reverse genetics (changes from genetic to phenotypic traits) which involves the identification of tissues and cells in various environments using gene chip or bioinformatics candidate genes with obvious differential expression.
How does the CRISPR/Cas9 system work? Fundamentally, the CRISPR/Cas9 system is made up of a DNA-specific nuclease that is guided by an RNA-DNA match, acting at a particular sequence of about 18 – 20 base pairs (bp) and creating a double-stranded break which are naturally fixed by the non-homologous end-joining repair mechanism. More accurate repair like the homologous repair may be required if the lesion tends towards the end of the sequence. New defined sequence may be introduced into the double stranded break using a plasmid. Examples of plants whose genome have been successfully edited include: tomatoes, arabidopsis, barley, maize, soybean, sorghum and rice. The properties of the CRISPR system can now be adjusted through the development of multiple variations. For example, by varying the length of the RNA: DNA guide to be either shorter or longer, the precision of the match is alternated.
Figure 3: Mechanism of the CRISPR/Cas9 system-mediated gene editing process. pCas9 plasmid is made up of sgRNA, cas9 gene, homologous arms and resistance locus. The function of the Cas9 and sgRNA gene is to identify target DNA and cleave at specific sites in front of PAM. The nuclease domain in Cas9 which function to cleave target DNA and its antisense strand are RuvC and HNH, respectively. The plasmids homologous arm sequences are complementary to their genome counterparts.
Source: Hao et al. (2018)
Answering the ultimate question, could the discovery of gene editing technologies be the answer to Nigeria’s food insecurity crisis? Tropical countries to which Nigeria belong is currently hosting more than two third of the world extremely poor people with a recent declaration of nutrition emergency in some parts of Northeastern Nigeria by the World Health Organization (WHO). In 2018, Nigeria was ranked the poverty capital of the world with an estimate of 90 million people said to be living in poverty. There is a link between food security, chronic hunger and poverty. Poverty is a multifactorial concept that is both a cause and consequence of malnutrition and food insecurity. Salvaging the problem of malnutrition and food insecurity in Nigeria is a critical issue that requires a combinatorial approach one of which must include modern biotechnology.
The Food and Agricultural Organization of the United Nations (FAO) has underscored five big challenges confronting the world agricultural system: escalating human population growth, increased life expectancy, biodiversity loss, climate change and accelerated land degradation. The intervention of a technified agricultural system is urgently needed to salvage the current food crisis. The fact that modern agricultural practice is not a holistic approach to tackling food crises in Nigeria cannot be over emphasized as up to 15% pre-harvest yield losses have been accounted to diseases of major food crops.
Figure 3: The link between Malnutrition, Food insecurity and Poverty
Source: Müller and Krawinkel (2005)
A significant landmark in the history of humanity is projected to be achieved by 2050 when the world population will have increased from 7.3 billion to 9.7 billion with Nigeria being among the lead country. Nigeria, which is currently the seventh most populous country in the world, is the second among the nine countries where more than 50% population growth are expected by 2050. The other eight countries are: India, Democratic Republic of the Congo (DRC), Ethiopia, Tanzania, Indonesia and Uganda respectively. It’s also unfortunate that climate change is exacerbating issues as it has already become one of the biggest threat to human survival worldwide causing the evolution of new insect pests, emergence of new diseases, altered weather patterns, increased environmental stresses like soil salinity, drought and flooding and loss of land. Already, the report by the International Rice Research Institute (IRRI) shows that one hectare of arable land is lost every 7.7 seconds, more alarming is the fact that the rate of loss may escalate with increasing global temperatures. Nigeria will have to increase her food production by 50% before 2030 if she must feed her consistent growing population. This is not an impossible task if crop varieties with higher yield, better adaptability to the changing climate as well as more tolerant to biotic and abiotic stresses are developed in the next decade on urgent basis. The editing of a plant genome at defined sites by precise nucleases has revealed possibilities for improvement of crops to meet the rising demands of food in Nigeria. For food production to match the escalating population, new approaches such as the gene editing technology will be required to improve crop production while reducing the need for chemical fertilizers and other chemical sprays that enhance the release of greenhouse gases.
In conclusion, there are several benefits that the gene editing technology can bring to the Nigerian economy. There is currently the seasonal acute scarcity of tomatoes in Nigeria due to spoilage by insect pests infestation which can be easily mitigated by the application of gene editing technologies. Several crops that usually add to the Nation’s gross domestic product (GDP) like cocoa and sugar have lost their monetary value in the international market due to land infertility and insect pests infestation. The genome of these crops can be edited to naturally produce decaffeinated coffee and sugarcane with higher biofuel conversion rates respectively that will thereby tackle Nigeria’s food insecurity and boost her GDP. Nigeria with a population of more than 180 million, is fully ripe for the technology as the country has several competent scientists that can accurately handle the technology to solve food and nutritional crisis. We should therefore arise and cease the full opportunities presented by the genome editing technologies.
A publication of Open Forum on Agricultural Biotechnology (OFAB) in Africa
c/o National Biotechnology Development Agency (NABDA),
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