27 Nov 2024

What Are The Plant Genetic Preservation Techniques?

Anjali Singh, MS

As a content and community manager, I leverage my expertise in plant biotechnology, passion for tissue culture, and writing skills to create compelling articles, simplifying intricate scientific concepts, and address your inquiries. As a dedicated science communicator, I strive to spark curiosity and foster a love for science in my audience.

Table of Contents

Introduction

Who wouldn’t want to see, feel, or enjoy their favorite fruits, flowers, and foods thriving for generations to come? Plant Genetic Preservation ensures that the plants we love—and depend on—can withstand pests, diseases, and changing climates.

It’s about more than farming; it’s about safeguarding the variety that makes our lives flavorful, nutritious, and beautiful. Imagine losing your favorite fruit or a key crop disappearing from markets—preserving plant genetics prevents that.

For typical people, this means stable food prices, healthier diets, and the reassurance that future generations can enjoy the same natural abundance we do today. 

It’s an investment in the future we all share!

But how can one preserve plants' genetics? What do we need to do? What are the approaches? Let’s get to the answers to all of these questions one by one. 

Why Do We Need to Preserve Plant Genetics?

As the global population is project to grow by an estimated 2.3 billion people by mid-century, increasing pressure mounts on food production systems.

Coupled with the challenges of climate change and land degradation, the need to preserve plant genetic diversity has never been more urgent. 

Genetic conservation safeguards the variety of traits that crops need to adapt to shifting environments, resist diseases, and ensure consistent food supplies. Without these genetic resources, we cannot sustainably meet rising food demands.

Moreover, the loss of biodiversity is occurring at an alarming rate, with many species and their unique genetic traits disappearing forever. This erosion of genetic diversity threatens not only our ability to produce food but also the delicate ecosystems that support agricultural resilience. 

By prioritizing genetic conservation, we can protect the building blocks of our food system, enabling farmers to sustain crop production while preserving the environment. This dual focus ensures a more secure future for both humanity and the planet.

Techniques of Plant Genetic Preservation

The conservation of plant genetic resources (PGRs) has been integral to agriculture since its inception. Early farmers practiced the selection, cultivation, and preservation of seeds from locally adapted plants, known as "landraces." 

These diverse and hardy plant varieties laid the foundation for food security across regions. However, the 20th century saw a shift with the rediscovery of Gregor Mendel's work, which led to breeding programs focused on high-yield, stress-tolerant crops. 

While this revolutionized agriculture and boosted production, it also caused the loss of over 75% of PGR diversity and 90% of traditional crop varieties due to the dominance of monoculture systems.

In response, efforts to conserve the remaining PGRs became critical, particularly as climate change and environmental pressures threaten global agriculture. 

One major technique is ex-situ conservation, where PGRs are preserved outside their natural habitats in specialized repositories called gene banks. These facilities, now numbering over 700 worldwide, store millions of crop accessions, including landraces, wild relatives, and breeding materials. 

Since the 16th century, botanical gardens have also played a role in collecting and preserving over 80,000 plant species globally. International treaties further ensure the equitable sharing and sustainable use of these resources.

By preserving genetic diversity through gene banks, breeding programs, and conservation treaties, we can maintain a treasure trove of genetic materials critical for developing resilient crops and sustaining global food security in the face of modern challenges.

In-Situ Conservation

In situ conservation involves safeguarding plant genetic resources within their native environments and maintaining species in their original locations. This method allows plants to evolve naturally with minimal human interference, ensuring genetic diversity continues to thrive. It is especially effective for conserving wild plant species, such as forest crops and wild fruits, as they adapt to their ecosystems over time.

This conservation strategy is implemented through two key approaches:

1. On-farm conservation focuses on preserving traditional crop varieties and farming systems. Farmers play a critical role by managing locally developed landraces and maintaining wild relatives and weedy forms within existing agricultural setups. Farmers cultivate desirable plants for future use through natural selection and intervention, fostering a process of continuous evolution.
2. Genetic reserve conservation involves designated areas, such as forest reserves, where wild plant species' genetic diversity is actively and sustainably protected over the long term.

A distinct advantage of in situ conservation is that it allows open pollination among various genotypes, producing diverse populations with multiple alleles. This natural process makes plant species more adaptable to changing environments.

While in situ conservation is invaluable for fostering genetic diversity and resilience, its success is vulnerable to climate change and natural disasters. For comprehensive preservation it is often complemented by ex-situ conservation, creating a robust system to secure the genetic resources critical for global agriculture and biodiversity.

Ex-Situ Conservation

Ex situ conservation utilizes several methods, including seed gene banks, plant tissue culture, cryopreservation, and botanical gardens. These techniques create controlled environments to preserve genetic material safely and sustainably. The primary methods are explained below:

Seed Banks

Seed storage is one of the most efficient and widely used methods for ex-situ conservation. Seeds of food crops, particularly orthodox seeds (seeds that tolerate drying and freezing), are stored under low temperatures and intense dehydration to ensure long-term viability.

• 45% of stored seeds in gene banks belong to cereal crops such as rice, wheat, maize, barley, and sorghum.
• Food legumes (15%), forages (9%), and vegetables (7%) also make up significant proportions of stored accessions.

Seed storage is categorized into three main types based on storage duration and conditions:

1. Long-term storage: Seeds are stored at −18°C to −20°C with moisture content between 3%-7%, ensuring viability for decades.
2. Medium-term storage: Suitable for up to five years, seeds are maintained at 0°C to 10°C with 20%-30% relative humidity.
3. Short-term storage: Lasting up to two years, seeds are kept at 20°C to 22°C with 45%-50% relative humidity, ensuring quick access for immediate use.

While this method is cost-effective and space-efficient, it has limitations. Recalcitrant seeds, like those of vegetatively propagated crops (e.g., yam and potato), cannot survive low-temperature conditions.

Botanical Gardens

Botanical gardens play dual roles in conservation and education. These gardens house rare, endangered, and ornamental plant species, offering a controlled environment to protect and propagate them.

• Some botanical gardens also include seed banks and tissue culture labs to enhance their conservation capabilities.
• By raising public awareness, these gardens emphasize the importance of plant preservation and inspire action against species extinction.

Gene Banks

Gene banks store living samples of crop varieties and their wild relatives. The genetic resources are carefully documented, characterized, and periodically regenerated to prevent the loss of viability.

• Gene banks are critical for providing access to genetic material for researchers, breeders, and farmers, ensuring food security and biodiversity conservation.
• However, managing gene banks involves challenges, including the need for periodic regeneration and the risk of genetic erosion.

Advantages of Ex Situ Conservation

Ex situ conservation offers several benefits that complement in situ conservation strategies:

• Provides controlled conditions for the study of plant biology and threats.
• Enables the conservation of endangered species when their natural habitats are at risk.
• Allows the collection and storage of genetic material for future breeding programs and biodiversity restoration.
• Supports educational efforts to raise awareness of plant preservation needs.
• Facilitates sustainable use of plants without harming wild populations.

Biotechnological Approach to Genetic Preservation

Tissue culture involves preserving plant tissues in lab conditions, making it an effective way to conserve genetic material for species with limited seed production or long life cycles.

In Vitro Propagation

In vitro propagation involves cultivating plant genetic material on an artificial nutrient medium, creating a controlled environment for their preservation. Recognized by global organizations like the International Board for Plant Genetic Resources (IBPGR), this method is especially effective for vegetatively propagated plants.

Key Benefits of In Vitro Propagation:

• Produces insect- and disease-free material.
• Enables mass multiplication throughout the year.
• Eliminates the risk of genetic erosion.
• Reduces space and labor requirements.

This technique regenerates whole plants from explants such as seeds, tubers, or leaves. While regular subculturing is necessary to maintain genetic material, it poses risks like microbial contamination or somaclonal variations. For medium-term conservation, slow-growth techniques, such as using low temperatures (0–5 °C for cold-tolerant species and 15–20 °C for tropical species) or light restrictions, effectively extend the viability of stored plantlets for 1 to 15 years.

Cryopreservation

Cryopreservation stores plant tissues at ultra-low temperatures (−196 °C) using liquid nitrogen, halting all metabolic activity. This method ensures long-term conservation without the need for periodic subculturing, minimizing the risk of somaclonal variations.

Steps in Cryopreservation:

1. Dehydration: Removal of freezable water using techniques like osmotic dehydration or vitrification.
2. Freezing: Ultra-rapid freezing to avoid ice crystal formation, preserving tissues in an amorphous state.

This approach is cost-effective, maintains genetic stability, and eradicates pathogens through cryotherapy. Only meristem cultures or shoot apices are used due to their high viability after long storage durations.

DNA Banks

DNA banking is a modern molecular approach for preserving genetic material. It involves storing genomic fragments, individual genes, or entire genotypes in libraries for future research and breeding. DNA can be stored in forms such as RNA, cDNA, or genomic DNA at temperatures as low as −70 °C for long-term preservation.

Notable DNA Banks:

• The Royal Botanic Garden (UK): Houses over 20,000 DNA samples, making it the most comprehensive repository.
• Australian Plant DNA Bank and Leslie Hill Molecular Systematics Laboratory are also prominent DNA conservation facilities.

Although DNA banks cannot directly regenerate whole plants, researchers use the stored DNA in in vitro tissue culture techniques to reintroduce genetic material into somatic cells for plant regeneration.

Digital Sequence Information (DSI)

Advancements in DNA sequencing have led to the digitization of molecular data, providing a valuable resource for scientific research and biodiversity conservation. DSI facilitates the analysis of genetic information to enhance food security and sustainable biodiversity use.

Challenges with DSI:

• Limited access due to policy restrictions.
• Unclear regulations on benefit-sharing among provider countries.

Despite these obstacles, open access to DSI could accelerate biodiversity conservation efforts, offering a transformative tool for global food security and environmental sustainability.

Why Biotechnological Approaches Matter

Biotechnological methods bridge the gap between preserving genetic resources and utilizing them for research and conservation. Techniques like in vitro propagation and cryopreservation conserve plant materials without genetic loss, while DNA banking and DSI drive future innovations. By integrating these technologies, scientists can secure the genetic diversity necessary for crop improvement, environmental restoration, and combating climate change.

Integrating Conservation Approaches

While ex-situ conservation excels in protecting genetic resources in controlled environments, it is most effective when combined with in situ conservation. This integrated approach ensures the long-term survival and adaptation of plant species, balancing natural evolutionary processes with artificial safeguards.

Plant Cell Technology: Empowering Culturists in Plant Conservation

Plant cell technology is transforming how culturists approach plant conservation by offering comprehensive resources and training in tissue culture techniques.

Key Offerings:

• Masterclasses:
• Expert-led training sessions to teach core tissue culture techniques.
• Practical skills like preparing nutrient media, contamination prevention, explant preparation, and best acclimation practices.
• Ideal for beginners and experienced culturists alike.

• Learning Resources:
• Detailed blogs and step-by-step video tutorials for self-paced learning.
• Accessible guidance on advanced techniques for large-scale propagation.
• Support Services:
• High-quality materials, such as sterile containers, media kits, PPMTM for contamination prevention, laminar hood, plant hormones, and much more.
• Consultation services for personalized advice when challenges arise.

Plant cell technology is enabling culturists to master tissue culture, contributing to sustainable agriculture and biodiversity conservation on a global scale.