Introduction
Climate change is defined as long-term alterations in global or regional climates that pose significant challenges to agriculture by directly impacting plants, animals, and microbes. The development of crop varieties resilient to abiotic stress is crucial for addressing these challenges.
Abiotic Stress and Crop Resilience
Abiotic stresses, including drought, extreme temperatures, salinity, and flooding, are major constraints on crop productivity.
- Drought Tolerance: Traits like stomatal regulation, root architecture, and osmotic adjustment enhance drought tolerance. Reduced stomatal density and deeper root systems improve water use efficiency. Deep, extensive roots help to access the water from deeper soil layers.
- Temperature Tolerance: Heat tolerance involves heat shock proteins, antioxidants, efficient photosynthesis, and carbon metabolism mechanisms by maintaining heat-induced denaturation cellular metabolism, and mitigating oxidative damage caused by heat stress. Cold tolerance relies on cellular membrane stability and osmotic balance, which is essential to maintaining cellular integrity.
- Salinity and Flood Tolerance: Salinity tolerance depends on ion homeostasis, osmotic adjustment, and oxidative stress mitigation. Flood tolerance involves root adaptations like aerenchyma and adventitious root formation and activation of anaerobic metabolic pathways.
What Is Climate-Resilient Agriculture?
Climate-resilient agriculture focuses on farming systems and practices that adapt to and mitigate the impacts of climate change, including extreme weather events such as droughts, floods, and heat waves. It also addresses shifting pest and disease patterns, ensuring stable agricultural productivity in changing climates.
Impact of Climate Change on Agriculture
Climate change exacerbates abiotic stresses, with temperature extremes, droughts, floods, and salinity severely reducing crop yields. It also promotes shifts in pest and pathogen distributions, intensifying agricultural challenges.
Elevated CO2 increases the severity of certain plant diseases, such as barley yellow dwarf virus in wheat. The combined drought and heat stress significantly reduces yields, particularly in cereals like maize and wheat, where even a 1 °C (33.8 °F) rise in temperature can lead to yield losses of up to 7.4%.
Water scarcity disrupts key physiological processes like pollination and grain-filling, while high humidity promotes pest infestations. Climate change models predict an increased prevalence of diseases such as Fusarium oxysporum spp. and Septoria in key crop-growing regions.
How Plant Biotechnology Helps
Plant biotechnology plays a pivotal role in developing climate-resilient crops through advanced breeding techniques and the use of genetic resources.
- Utilizing Genetic Resources
Wild crop relatives and landraces provide valuable genes for stress tolerance. Conventional breeding combined with molecular markers enables the transfer of these genes into cultivated crops, broadening genetic diversity and enhancing resilience.
- Next-Generation Breeding
Modern breeding incorporates germplasm collections, big data analysis, and advanced biotechnological interventions. Tools like OMICS, genome editing, and in vitro regeneration systems enable precise modification of crops, addressing pest resistance and abiotic stress tolerance. Genome editing technologies, such as CRISPR/Cas9, facilitate precise alterations, boosting crop resilience.
- Population Mapping and QTL Analysis
Mapping populations, including biparental, multiparental, and nested association mapping populations, allow the identification of genetic variations influencing key traits. Quantitative Trait Loci (QTL) mapping combined with marker-assisted backcrossing (MABC) introduces desirable traits like disease resistance into crops such as rice. Tools like genome-wide association studies (GWAS) identify Single Nucleotide Polymorphisms (SNPs) linked to stress tolerance.
- Genomic Selection (GS)
Genomic selection accelerates breeding cycles and reduces costs. Using high-throughput phenotyping and genotyping, GS predicts genomic estimated breeding values (GEBVs) to select superior genotypes. For example, the International Maize and Wheat Improvement Center (CIMMYT) has utilized GS to enhance heat and drought tolerance in wheat.
- Advanced DNA Sequencing Technologies
Next-generation sequencing (NGS) drives the genomic revolution, providing comprehensive insights into crop genomes. Combining genomic and phenotypic data accelerates trait selection and breeding strategies, offering solutions for climate-adaptive agriculture.
- Genetic Modification and Genome Editing
Genetic modification (GM) expands the range of traits that can be introduced, including drought, salinity, and heat tolerance. Genome editing allows precise modifications for pest resistance, abiotic stress tolerance, and higher yields. Techniques like oligonucleotide-directed mutagenesis (ODM) enable targeted DNA alterations to a plant’s DNA fragments that guide these alterations (used to introduce traits like herbicide resistance or stress tolerance in crops), although their efficiency remains low.
- Applications in Agriculture
Traits essential for climate adaptation include early seedling growth, efficient nitrogen use, pest control, frost tolerance, and improved water use efficiency. Nitrogen-efficient rice varieties, for example, reduce the need for fertilizers, lowering farming costs and minimizing environmental impacts. Genetic advancements also support eco-efficient farming practices, reducing greenhouse gas emissions and promoting sustainability.
Improving Nutritional Quality in Climate-Resilient Crops
- Biofortification: Involves increasing essential nutrients in staple crops like iron, zinc, and provitamin A (beta-carotene). This process utilizes natural genetic variation, conventional breeding, and molecular breeding tools like marker-assisted selection to improve nutrient content without compromising agronomic traits. Transgenic approaches have successfully enhanced provitamin A in rice and iron and zinc in other crops, offering a practical solution to nutrient deficiencies.
- Reducing Antinutritional Factors: Antinutritional compounds such as phytic acid, tannins, and oxalates interfere with nutrient absorption in the human body. Breeding strategies aim to reduce these compounds, improving mineral bioavailability and digestion. Molecular breeding and gene-editing tools target specific genes to minimize these factors while maintaining other desirable traits.
- Beyond Essential Nutrients: Improving amino acid profiles (e.g., lysine and methionine), fatty acids (e.g., omega-3), and vitamins (e.g., C and E) in crops contribute to a balanced diet. Advances in genomics have helped identify metabolic pathways and genes responsible for these traits, enabling precise breeding for improved nutritional quality.
Global Case Studies
- Golden RiceB: Developed using genetic engineering, Golden Rice accumulates provitamin A in its endosperm, addressing vitamin A deficiency. A child’s daily recommended allowance can be met with just 140 g of Golden Rice.
- SmartStax™ Maize: Approved by the United States Environmental Protection Agency (EPA) and Food Inspection Agency (CFIA), this genetically modified maize combines eight cry genes(Cry2Ab, Cry1A.105, Cry1F, Cry3Bb1, Cry34, Cry35Ab1, Cp4 and bar). The bar gene confers on herbicide tolerance functionality, while the Cry genes provide insect resistance. This combination makes SmartStax™ a "stacked" trait GMO, offering both pest and herbicide resistance.
- Submergence-Tolerant Rice: The SUB1A gene introduced by IRRI enhances rice's ability to survive submerged conditions, ensuring good yields after prolonged flooding.
- Thermometer Gene in Arabidopsis: Discovered in Arabidopsis, the H2A.Z histone protein enables plants to sense and respond to temperature changes by tightly binding and dropping off from the DNA at lower and higher temperatures and similar research is being applied to crop plants for stress adaptation.
- CRISPR/Cas-9 in Soybean and Cocoa: Gene editing has improved drought and salt tolerance by targeting genes like Drb2a and Drb2b, showcasing potential for wider application in climate-resilient crops.
- Drought-Resistant Maize: Monsanto's "Drought Guard" maize exhibits higher yields during droughts, supported by projects like “Drought Tolerant Maize for Africa” (DTMA), “Water Efficient Maize in Africa” (WEMA) and “Improved Maize for African Soils” (IMAS). This maize outperforms other varieties, yielding 20–50% more in water-limited conditions.
- Improved Root Architecture in Rice: The DEEPER ROOTING 1 (DRO1) locus enhances root depth and vertical growth, improving drought tolerance, yield, and nitrogen uptake.
- Salt Tolerance in Tobacco (Nicotiana tabacum L.) and Tomato (Solanum lycopersicum): Genes like an aquaporin coding gene NtAQP1 in tobacco improve water-use efficiency and prevent salinity stress in transgenic plants, benefiting crops like tomatoes.
Benefits of Climate-Resilient Crops
- Increased Crop Yields: Drought-tolerant maize and salt-tolerant rice varieties yield 20–30% more than traditional crops under adverse conditions.
- Improved Nutrient Use Efficiency: Biotechnology has enabled nitrogen-efficient rice varieties that maintain yields with reduced fertilizer use, minimizing environmental harm.
- Adaptation to Climate Variability: Traits like early flowering and enhanced photosynthesis, developed using CRISPR and other gene-editing techniques, stabilize yields under fluctuating weather patterns.
- Economic Benefits for Farmers: Biotech crops reduce input costs, increase yields, and improve profitability, particularly in regions vulnerable to climate impacts.
- Sustainability Improvements: Reduced chemical inputs and eco-friendly farming practices support biodiversity and promote sustainable agriculture.
Practical Tips for Farmers
- Crop Diversification: Growing multiple crops reduces risk and enhances adaptability.
- Using Climate-Resilient Varieties: Selecting drought and heat-tolerant crops ensures stable production.
- Soil Management: Maintaining healthy soils improve stress tolerance.
- Water Conservation: Harvesting rainwater and efficient irrigation techniques enhance water availability.
- Breeding Methods: Farmers have benefited from breeding techniques like Selection by identifying and propagating plants with superior traits (e.g., drought tolerance), Hybridization by combining traits from diverse parent plants for improved stress tolerance and Mutation Breeding by inducing genetic variations to develop resilient crop varieties.
References
- Munawar, S.; ul Qamar, M. T.; Mustafa, G.; Khan, M. S.; Joyia, F. A. Role of Biotechnology in Climate Resilient Agriculture. Environment, Climate, Plant and Vegetation Growth 2020, 339–365. https://doi.org/10.1007/978-3-030-49732-3_14.
- Dhanya, C.; Mathay. The Role of Biotechnology in Climate-Resilient Agriculture. JSS Journal for Legal Studies and Research 2024, 10 (2), 104–116.
- Hafeez, U. Advances in Breeding and Engineering Climate-Resilient Crops: A Comprehensive Review. ResearchGate. Published online 2024. (URL: https://www.researchgate.net/profile/UzmaHafeez3/publication/372993016_Advances_in_Breeding_and_Engineering_ClimateResilient_Crops_A_Comprehensive_Review/links/64d3734dc80b930269f9c64e/Advances-in- BreedingandEngineeringClimateResilientCropsAComprehensiveReview.pdf ) (Accessed December 29,2024)