Ok I know the title is a lot to take in. I was intimidated when I decided to take the topic on myself. But turns out that Epigenetic Biology is not that hard to understand, and the findings are highly significant for sustainable farmers. Let’s understand this step by step. (Stick with it or skip to the end for some practical gardening tips)
The Old Concept of Genes and Traits
We’ve all heard of DNA right? This is the genetic structure that is unique to every species and variety of plant, animal and human on Earth. Each one has a unique DNA structure that sets them apart from all others. DNA dictates a lot about an organism’s characteristics. The way it looks and behaves is largely a product of it’s DNA structure. DNA stays the same throughout an organism’s life and is largely unchanged over generations as well. While there are a few genes that express differently, giving rise to different features and traits, the main structure remains mostly identical. To give you an idea of how stable it is, human DNA has not changed since we officially became homo sapiens thousands of years ago. For decades we have assumed that the traits you are born with are encoded in your DNA and cannot change within a lifetime. These concepts were first discovered in the 1800’s.
What We Now Know
Around 1988, a new field of study called Epigenetic biology was born. Driven forward by many successful and significant experiments, there has been a revolution in the way we see genetics. We now know that DNA alone does not contain all the information that determines the characteristics of an organism. The Human Genome Project was a massive, international experiment which scientists conducted in the hope of finding the hundreds of thousands of genes that are responsible for these variations. What the found instead was that we only have about 25,000 different sets of genes. Each one of these however, are able to express and adapt in 30,000 ways!
These findings defy the old school of thinking, and it has been demonstrated that these genes are responsible for potentially significant changes in minor characteristics even within the lifetime of an organism. This means that organic life can actually change or develop traits to adapt to external stimuli. Some of these traits can be passed on to the next generation if appropriate, or may even be discarded if inappropriate. This has totally turned the idea of molecular genetics on it’s head, and has many social, agricultural, and environmental implications.
Epigenetic Biology Experiments on Plants
Studies have shown that plants rely heavily on epigenetic modification to ensure health and optimum growth. They are masters of epigenetic adaptation! These changes have been observed in specimens with identical DNA exposed to different external conditions. Epigenetic changes can be seen in the fertilization process, allowing new generations of plants to be better adapted to the specific stimuli which the previous generations were exposed to.
Furthermore, plants also exhibit epigenetic changes during the transition from vegetative stage to reproductive stage. This manifests in some amazing ways!
· Plants have shown the ability to respond to herbivores grazing on them. Plants attacked a second time react more strongly and rapidly than the first experience. The offspring of these plants exhibit the augmented reactions even on initial grazings.
· Plants are able to adapt to temperature changes, for example in winter annuals, which are able to hold off their reproductive stage until the onset of spring, which may vary. These changes are note passed on to the next generation, as they will likely experience a different set of conditions. This shows that plants are also able to withhold transfer of epigenetic changes when it is important to give the next generation a “fresh start”.
Significance for Sustainable Agriculture
Epigenetic biology has many important implications for agriculture in general, and more so for sustainable agriculture. Conventional agriculture has the tendency to view plants in a highly mechanistic manner, and this paradigm highly underestimates the amazing ability of plants. This leads to many unnecessary interventions, in the form of fertilizers, pesticides and fungicides.
However epigenetic biology confirms one of the pillars of sustainable agricultural practice: that healthy plants have a measure of intelligence and are able to adapt and solve most problems on their own.
Take pest damage for example. A conventional farmer will quickly spray pesticides at even the smallest sign of insect damage. However if left alone, healthy plants will overcome the damage and may even grown stronger to compensate. Apart from this, they will also begin to produce minute pest repellent compounds in their leaves and stems, making continued attacks less likely. The plant is already beginning to exhibit new characteristics, and these are potentially passed on to the next generation.
Another example is the dependence of conventional farmers on Urea (synthetic nitrogen). Application of synthetic fertilizers completely circumvent a plant’s natural feeding process, making them dependent on continued application. Sustainable farmers are aware of the fact that healthy plants grown in soil rich in organic matter actually secrete food into the soil through their roots in order to encourage good soil ecology. This ecosystem and the waste it creates, feeds the plant in turn. The more a plant is forced to rely on this natural exchange to get it’s food the better it gets at it. Over time and generations, less input is required as the plants get better at working with the soil biology to create fertility. Feeding Urea does not encourage this and is basically spoon feeding a plant. As sustainable farmer once told me: Kung tamad ang farmer, tamad ang tanim”
Seed Saving also saves Adaptive Traits
As you can see, there are countless implications that support and prove the advantages of the sustainable farming system. The most important however may be the fact that some of these traits are passed down to the next generation. In conventional farming, not much thought is given to seed saving. After all, any seed will grow if spoon-fed and protected from all outside threats. However this is costly, both to the farmer and to the environment.
Epigenetic biology illustrates why for sustainable farmers, seed saving is ESSENTIAL. Aside from the two processes mentioned above, plants also record information on weather, soil conditions, water availability and may even learn to recognize the farmer. All this information is passed on to the next generation, where these minor traits may be amplified even further. Over time, the farmer finds that they are in possession of a highly improved variety, adapted to their farm’s specific conditions, and able to care for itself more efficiently.
All of these of course, mean less energy and resources required for good cultivation. Even commercial seeds can be detoxified by being grown out organically, and over the course of a few generations, will begin exhibiting more and more natural biological activity. The plant will be more pest tolerant, require less fertilizer and be more resilient to environmental conditions. the sustainable farmer will find that they soon will getting better results with equal or less efforts. The more consistent your practices are, you will provide the plant to strengthen the traits it needs to thrive in these conditions.
Epigenetic Breeding Works
Traditionally, plant breeding is seen as a process of cross-pollination. These findings however prove that selection is responsible for 99% of the traits of new generations of plants!
The single greatest implication of Epigenetic biology in agriculture is that selection of favorable specimens for propagation works, meaning you can breed your own varieties simply by choosing to propagate plants that exhibit the traits you prefer. George Washington Carver was one of the individuals who explored this to a great extent, breeding some truly remarkable varieties through selection.
There is a lot to talk about when it comes to epigenetic breeding in plants. So much so that we will have to write a separate article on this. But for now it is just worth understanding that Epigenetic biology allows plants to adapt to new conditions within a generation or even a lifetime. This means that even home gardeners can easily breed their own personal and highly resilient varieties by applying different stressors and extreme conditions to their plants, and saving the seeds.
A conventional farmer cannot hope to have these benefits, as their plants have not been exposed to the conditions conducive to improvement. So they are reduced to buying new seeds every season (which were grown in a different environment from their own farm), applying the same or even more amount of chemicals to achieve the same results. This is the law of diminishing returns.
There is still much to be learned about epigenetic biology but even the first wave of experiments have yielded very promising results, confirming that sustainable agriculture is not only better for the earth, but also better for the farmer.