How CRISPR can Revolutionise Nitrogen Fixation

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Nitrogen is a fundamental element for plant growth. It plays a crucial role in the development of vital molecules such as proteins and nucleic acids. But despite its abundance in the atmosphere, nitrogen is mostly inert and unavailable to plants in its gaseous form. So, farmers have traditionally relied on synthetic fertilisers to supply crops with accessible nitrogen. But as we have seen from the recent climate-change issues plaguing us, this approach is fraught with inefficiencies and environmental concerns.

According to reports, approximately half of all applied nitrogen fertiliser is wasted. The consequences of this waste include economic losses and environmental damage. As the global population is projected to reach nearly 10 billion by 2050, according to the United Nations, the demand for efficient and sustainable agricultural practices has never been higher. Walk with me as I discuss the nitrogen fixation process and CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) as a possible upgrade to traditional nitrogen fixation.

The Nitrogen Fixation Process

Nitrogen fixation is a natural process by which certain microorganisms convert atmospheric nitrogen (N₂) into ammonia (NH₃), a form that plants can readily absorb and utilise. This process is primarily carried out by symbiotic bacteria, such as Rhizobium, which form mutualistic relationships with leguminous plants. These bacteria colonise the root nodules of legumes, providing them with a direct source of nitrogen while receiving carbohydrates and a conducive environment for their growth.

In non-leguminous crops, such as cereals and vegetables, nitrogen fixation is absent. To fulfill their nitrogen demand, farmers use synthetic fertilisers. These fertilisers have shown to be inefficient, resulting in economic losses for farmers and other environmental damage. For instance, fertiliser runoff leads to eutrophication of water bodies, causing algal blooms, dead zones, and loss of aquatic biodiversity. The Environmental Protection Agency (EPA) has often highlighted the detrimental effects of nitrogen pollution on ecosystems. So for us to maintain a safe ecosystem, we must consider and explore sustainable alternatives. 

CRISPR Gene-Editing Technology

CRISPR is a gene-editing technology that allows for precise modifications in an organism’s DNA. Scientists utilise a guide RNA to target specific genetic sequences and the Cas9 enzyme to introduce breaks in the DNA. As a result, they can add, remove, or alter genetic material with unprecedented accuracy. This technology has opened up new possibilities for agricultural biotechnology, including the potential to optimise nitrogen fixation in crops beyond legumes.

Source: iStock

CRISPR may have a role to play in nitrogen fixation in crops. One of such exciting avenues is in enhancing symbiosis in legumes. Using CRISPR, scientists target genes that control nodule development and function. The process works by fine-tuning genes involved in oxygen regulation within nodules, for instance. Researchers can then create an environment more conducive to the nitrogenase enzyme, optimising nitrogen fixation rates.

Another exciting application of CRISPR in agriculture is the possibility of engineering non-leguminous crops to fix nitrogen. It involves introducing the nitrogen fixation (nif) genes from diazotrophs (bacteria and archaea that fix atmospheric nitrogen in the atmosphere into bioavailable forms such as ammonia) directly into the genome of non-legume crops. CRISPR’s precise gene-editing abilities make it a powerful tool for achieving this. However, this strategy has always been up for debate among experts because:

1. Scientists need to identify the minimal nif gene cluster necessary for efficient nitrogen fixation and ensure its proper regulation within the non-legume plant’s metabolism.

2. The energy-intensive nature of nitrogen fixation necessitates optimising the plant’s energy production pathways to support this process. 

Challenges in CRISPR in Developing N-Fixation in Non-legumes

Despite the promise of CRISPR in enhancing nitrogen fixation, we must address several challenges before this technology can be widely implemented. For the sake of this article, let’s group these challenges into scientific and regulatory, each contributing to the success or failure of the research. 

Scientific Challenges

One of the primary concerns is the potential for off-target effects. CRISPR relies on the specificity of the guide RNA to target precise locations in the genome. However, unintended modifications at off-target sites can occur, leading to undesirable mutations. The complexity of the nitrogen fixation process itself also poses another challenge. Nitrogen fixation involves a multitude of genes and regulatory pathways that must be carefully coordinated for successful integration into non-leguminous crops. 

So to achieve functional nitrogen fixation in new plant hosts, we must understand the intricate interactions between these genes and their expression patterns. In a nutshell, this feat cannot be achieved without investigating the genetic and biochemical mechanisms underlying nitrogen fixation to develop effective strategies for transferring this phenomenon to a broader range of crops.

Source: iStock

Regulatory Challenges

Regulatory frameworks for GMOs vary across countries, reflecting different approaches to risk assessment, safety protocols, and public policy priorities. These frameworks are designed to ensure the safety of gene-edited organisms for human consumption and environmental release. However, they can also become serious obstacles to the development and deployment of innovative biotechnologies like CRISPR. Some regulatory challenges to consider include:

• Safety Assessments: Regulatory bodies require extensive safety assessments, including rigorous field trials and environmental impact studies, before approving GMOs. These assessments are crucial for identifying potential risks but can be time-consuming and costly. For CRISPR-mediated nitrogen fixation, demonstrating the stability and efficacy of nitrogen-fixing traits in various environmental conditions is essential.

• Regulatory Variability: Different countries have different regulatory standards and processes. For example, the European Union has stringent regulations for GMOs, requiring comprehensive safety evaluations and labeling. In contrast, countries like the United States and Canada have more streamlined regulatory processes that focus on the characteristics of the final product rather than the method used to create it. This variability can create challenges for researchers and companies aiming to commercialise CRISPR-engineered crops globally.

• Intellectual Property Rights (IPR): The patenting of CRISPR technology and specific genetic modifications may lead to legal disputes and hinder collaborative research efforts. Clear and fair IPR frameworks and international biotech standards are essential to encourage innovation while ensuring that benefits are widely accessible.

Public Perception of GMOs

I had a lengthy discussion with colleagues when videos of conspiracy theories around GMOs were flying around. Some of them opined against purchasing GM foods if they had the choice. In fact, there’s public panic at the mention of GMOs and public perception will definitely influence regulatory policies and the adoption of gene-edited crops. Despite the scientific consensus on the safety and potential benefits of GMOs, public skepticism and opposition remain strong in many regions. These misconceptions may come in form of:

• Misinformation and Fear: Misinformation about GMOs, often fueled by sensational media reports, conspiracy theories, and activist campaigns, contributes to public fear and resistance. Concerns about the potential health risks, environmental impact, and ethical implications of genetic modification can overshadow scientific evidence supporting the safety and benefits of GMOs.

• Cultural and Ethical Concerns: In some societies, there is a strong preference for natural and traditional farming practices, leading to resistance against perceived artificial interventions in agriculture. Ethical concerns about manipulating the genetic makeup of organisms also contribute to public apprehension.

• Transparency and Trust: Building public trust through transparency and effective communication is crucial for gaining acceptance of GMOs. Consumers want to know how gene-edited crops are developed, tested, and regulated. Clear labeling and open dialogue about the safety and benefits of CRISPR technology can help address public concerns and foster informed decision-making.

Source: iStock

Impact on Research and Adoption

The interplay between regulatory hurdles and public perception has profound implications for research and the successful adoption of CRISPR-mediated nitrogen fixation in non-leguminous crops: 

• Research Funding and Priorities: In regions with strong opposition to GMOs, securing public or private funding for research on gene-edited crops can be challenging. Researchers may need to invest additional effort in public outreach and education to garner support for their work.

• Regulatory Delays: Stringent and variable regulatory requirements can delay the approval and commercialization of CRISPR-engineered crops. These delays increase development costs and slow down the deployment of beneficial technologies that can enhance agricultural sustainability and food security.

• Market Acceptance: Even if regulatory approval is obtained, market acceptance remains a critical barrier. Farmers and consumers must be willing to adopt and purchase gene-edited crops. Public skepticism can limit market penetration to a significant level. Eventually, the potential impact of CRISPR-mediated nitrogen fixation on reducing fertiliser dependency and environmental pollution will reduce.

• Global Disparities: Disparities in regulatory approaches and public acceptance can lead to uneven adoption of CRISPR technology. Countries with more favorable regulatory environments and higher public acceptance may benefit from early adoption, while others may lag behind, missing out on the potential economic and environmental advantages.

Economic and Environmental Benefits

From an economic perspective, reducing the dependency on synthetic fertilisers can lead to significant cost savings for farmers. Now that global inflation is almost at an all-time high, the high cost of fertilisers constitutes a substantial portion of agricultural expenses. So to increase farmers’ profitability we have to consider reducing synthetic fertiliser use.

Environmentally, the benefits of CRISPR-mediated nitrogen fixation are equally compelling. When we decrease the reliance on synthetic fertilisers, we can equally mitigate the risk of nitrogen runoff and its associated environmental damage. This would result in healthier aquatic ecosystems, reduced greenhouse gas emissions from fertiliser production, and improved soil health.