One of these challenges is how we can keep the crops needed for feeding the world's increasing population healthy and growing. Many companies work tirelessly to develop new pesticides and fertilizers to make sure that the plants can grow even in the face of a changing climate. However, we do not have to look as far as synthesizing new chemicals to find a way to protect our food supply. For a sustainable and long-term solution to this problem, we can investigate something that can be found right where our crops grow: the tiny organisms living in the soil.

A Symbiotic Relationship

Contrary to popular belief, plants need more than just water, sunlight and minerals to grow to their full potential. While seeds can sprout on as little as a layer of kitchen paper, for many of its functions a plant needs close interactions with tiny helpers that can only be seen under the microscope. The soil microbiome consists of species from the classes of bacteria, fungi and archaea, many of which have not been identified and researched yet. Some fungi in the soil interact very closely with plant roots. The filaments of the fungi can even penetrate the roots, creating a large amount of shared surface area. The type of fungi that connects with a plant by this kind of growth is called arbuscular mycorrhizal fungi (AMF). The relationship between AMF and the plant is a win-win situation. The plant benefits from, for example, increased water uptake¹ and additional nutrients thanks to the fungi. In return, the fungi gain access to nutritional molecules that plants produce during photosynthesis. Because this strategy benefits both participants greatly, it is found very often in nature. Over 80% of plants interact with AMF².

Research

Besides AMF, many other fungi and bacteria have evolved mechanisms that help a plant survive and grow. For each plant species, there is an intricate network of interactions that needs to be understood to fully comprehend what drives the development of the plant. Many researchers have started studies that aim to identify which role each microbe plays in plant development and how the plant as a host interacts with the microbes around it. At Leiden University, for example, the group of Prof. Martijn Bezemer and Dr. Sofia Gomes is researching the microbiome in agricultural and forest environments. Because the composition of microbial communities can differ a lot between locations, many Dutch universities cooperate on such projects and samples are collected all over the country.

Microbes and Climate Change

So, what does understanding the effect of microbes on a plant have to do with climate change? Apart from their role in plant growth, there have also been studies that showed that certain bacterial and fungal species protect the roots of a plant during drought^3,4. Due to climate change, temperatures will rise, and drought will become more frequent all around the world⁵. This is why it is especially interesting to understand how exactly these mechanisms work and which species are responsible for them. If we can identify this, we might be able to develop crop treatments with suitable microbes that help them recover from drought and survive in increasingly harsh conditions. Adding self-preserving organisms to the soil is also more efficient in the long-term because we would not have to apply the same chemical treatment again and again. Identifying and adding the right microbe to the soil community is a bit like hiring a new team member: if you find the person with the right talents that fits into the group well, this will improve how the team functions not only for a few weeks, but also in the long run.

Agricultural research covers not only how plants cope with drought or salt, but also how to increase their tolerance to insects and viruses. The microbiome even affects the nutrient content of fruits and vegetables. Did you know that microbes in the soil directly influence the taste of our vegetables? While growing food is vital, the research on the soil microbiome is relevant for other fields too. The soil plays a crucial role in the birth and survival of forests. If we understand which little helpers trees need to feel at home on barren land, we can improve success rates for starting new forests during afforestation. Instead of wondering why plants die despite proper watering and sufficient sunlight, we would be able to first look at the soil and make sure that they find everything they need not only above, but also below ground. Soil in itself might not look too interesting, but once you use a microscope, you will see that the answer to a lot of questions waits right beneath your feet.

Sources

1. Arbuscular mycorrhizal symbiosis increases relative apoplastic water flow in roots of the host plant under both well-watered and drought stress conditions | Annals of Botany | Oxford Academic. https://academic.oup.com/aob/a....

2. Zobel, M. & Öpik, M. Plant and arbuscular mycorrhizal fungal (AMF) communities – which drives which? J. Veg. Sci. 25, 1133–1140 (2014).

3. Begum, N. et al. Co-inoculation of Arbuscular Mycorrhizal Fungi and the Plant Growth-Promoting Rhizobacteria Improve Growth and Photosynthesis in Tobacco Under Drought Stress by Up-Regulating Antioxidant and Mineral Nutrition Metabolism. Microb. Ecol. 83, 971–988 (2022).

4. Kour, D. et al. Alleviation of Drought Stress and Plant Growth Promotion by Pseudomonas libanensis EU-LWNA-33, a Drought-Adaptive Phosphorus-Solubilizing Bacterium. Proc. Natl. Acad. Sci. India Sect. B Biol. Sci. 90, 785–795 (2020).

5. Toreti, A. et al. Global Drought Overview September 2024. JRC Publications Repository https://publications.jrc.ec.eu... (2024) doi:10.2760/7511271.