Imagine your typical trip to the grocery store, walking through aisles filled with your usual shopping list—produce, dairy, snacks, and other items—comfortably picking up what you need. You can rely on the availability of produce and grains as staples in many households. However, this convenience is a privilege of our time. There may come a day when we can no longer take such abundance for granted as a result of the effects of the current climate change trajectory on the environment. Especially staple grains like corn, rice, and wheat could become seasonal or scarce, forcing consumers to carefully plan every meal around what’s available. The potential for empty grocery aisles and the absence of essential foods stand to serve as a stark reminder of how climate change has the potential to fully reshape our world. This shift would not only disrupt local food systems but also signal a global loss of stability and security, upending the very foundation of how we feed communities around the world.
Agriculture is an important pillar of society, continually used as bargaining chips in international relations and international wars. Beyond its relevance at the global stage, 75% of the world’s population earn most of their living through farming.1 Increasing and promoting agricultural productivity is widely viewed as a way to improve economic development and reduce poverty. Climate change, however, has enormously, and multidimensionally, impacted agricultural harvest. The immediate effects of the environmental stressors of climate change, such as droughts and floods, are reduced crop yields and soil fertility. These environmental stressors can also lead to a cascade of problems affecting the overall health of an ecosystem. In a comprehensive study published in Science by Yang et al from China’s Chongqing University alongside numerous international institutions, researchers found that this decline in crop yields and soil fertility could force farmers into clearing more land for agriculture to still meet their yearly harvest requirements. However, this would further result in the loss of wildlife habitats and biodiversity from the now cleared land.2.3 Simultaneously, climate change has worsened environmental and soil conditions, increasing our reliance on fertilizers and pesticides to sustain crop production. This overuse can similarly harm surrounding ecosystems, affecting birds, fish, beneficial insects, non-target plants, water quality, and even human health.2, 4
It is well known that the negative effects of climate change on our planet are extensive and damaging. Climate and temperature changes due to rising carbon emissions have had a wide-ranging effect on the global agriculture sphere. As per the June 2024 climate report from the National Centers for Environmental Information, the average temperature in the United States alone between January and June 2024 hit its second highest record yet.5 Additionally, the U.S. experienced a much drier season, resulting in low-moisture soil. Other regions, including South America, Europe, and Africa, also recorded their warmest temperatures yet, leading to similar effects.5 Cumulatively, these factors lead to drought stress, creating extensive detrimental implications for agricultural crops, predominantly maize, which loses around 15% of its global yield due to drought conditions.6 Given that the United States is the world’s largest producer, consumer, and exporter of maize—planting around ninety million acres annually—this issue is of immense national and international concern.7 Thus, acknowledging its importance and impact, Dr. Alexandra Jazz Dickinson’s Lab, in the School of Biological Sciences at UC San Diego, chose to focus their study on maize.8
Scientists, like those in the Dickinson Lab, have been studying the complex interplay between climate and agriculture to better prepare crops to withstand future changes in weather and climate. Researchers are currently studying ways to develop deeper, broader, and stronger plant root networks to specifically address low-moisture soil. This process allows plants to forage for nutrients and water deep in the soil, potentially increasing their resistance to drought and other climate-related stresses. They are tackling this study at the molecular level, focusing on the metabolites that influence root growth. By combining small molecule interactions and plant biochemistry, the Dickinson Lab investigates plant root metabolites to track corresponding stem cell activity and behavior, and thus control over root growth. A metabolite is a substance made or used when an organism breaks down food, drugs, and chemicals during metabolism. Notably they are instrumental in cell growth as different metabolites are increased during cell growth and division versus dormancy or death. Thus, by studying the relative concentrations of different metabolites, we can better understand the metabolic patterns of growth and stress resilience to engineer crops with stronger root systems. This knowledge can then be applied to maximize harvests, increase the sustainability of agriculture, and modify the plants themselves to combat the effects of climate change.
Strengthening Roots to Fight Climate Impact
Roots are the “heart” of the plant. Plant root systems that can dig deeper to acquire nutrients, fertilizer, and retain water live longer. Crops cultivated for human agriculture originate from wild species that were capable of “digging deeper”. These species were tough and able to survive without assistance or supplementation. Unfortunately, due to human intervention during the process of domestication for agriculture, these traits have been unintentionally selected against since these plants no longer actively compete for their own nutrients and water. Thus, the Dickinson Lab seeks to understand the mechanisms behind the strengthening of plant root growth, due to the potential of rediscovering these traits in crops that have weakened roots due to domestication. With this research they aim to understand how to not only to mitigate the current effects of climate change, but also how to engineer plants to continue withstanding future harsh climate conditions.
The Dickinson lab has specifically studied the plant root system in regards to the particular metabolites of the tricarboxylic acid (TCA) cycle. The TCA cycle, commonly known as the Krebs cycle, provides the energy necessary to sustain life across all plants and animals. In humans, TCA cycle intermediates play a significant role beyond just their traditional metabolic functions, influencing various signaling pathways impacting physiology and modulating innate and adaptive immune systems.9 In the plant root system, the TCA metabolites play an essential role in regulating root growth, making it possible to visualize several cell growth patterns through multiple stages of development by tracking TCA cycle metabolites. While this is an excellent focus for study, the TCA cycle is particularly tricky to study. For the study of most biological mechanisms, the preferred methodology is knocking out, or disabling, genes responsible for the function of interest and examining the physiological response. However, in the TCA cycle every metabolite is required to be present in order for the cycle to cascade and proceed forward. Each step is needed for the next, meaning the isolation and study of individual steps is difficult to pursue. As a result, diverse methods such as mass spectrometry imaging, chemical treatments, and tissue-specific genetic engineering are used.
At the Dickinson Lab, researchers specifically used mass spectrometry imaging to spatially visualize and map the metabolites present. Mass spectrometry imaging is an analytical tool used to measure spatial distribution of molecules.10 DESI-Mass Spectrometry Imaging, the type used by these researchers, involves spraying a cryosection, or a frozen thin slice, of plant tissue with a stream of charged droplets of a specified solvent. The solvent interacts with the molecules of interest, in this case metabolites, manipulating them to maximize their presentation in the imaging data collected by the mass spectrometer. This imaging data then determines the relative distribution of different metabolites regionally.11 The varied distribution of different metabolites in each area of the root can help guide the understanding of what chemical composition is necessary to stimulate and hinder root growth and differentiation – those present at higher concentrations towards the tip and branching points likely push root stem cells to divide and grow and those in dormant areas likely do the opposite. A combined understanding of this entire metabolite-map of the root system of a plant, including the tips, branching points, and dormant areas, can act as a first step in figuring out how to engineer root systems of important crops.
Understanding Root Growth Through Metabolites
For both maize and Arabidopsis (a common plant model), different TCA metabolites were found in opposing developmental areas (i.e., in areas of growth and division as well as dormancy). Two primary metabolites, succinate and aconitate, were found to accumulate in distinct regions of the root. Succinate was found to be concentrated in the meristem, at the tip of the root which holds the undifferentiated stem cells that divide and grow into different cell types.11 In contrast, aconitate, and other related TCA metabolites like malate and fumarate, were generally concentrated in the root differentiation zone, where cells begin to mature and specialize.11 Therefore, it was concluded that while succinate encourages rapid expansion of the root through stimulating proliferation of stem cells in the tip, aconitate guides the transition of these cells into their final, specialized forms as they move toward the differentiation zone.
Interestingly, it was found that the distribution and development of TCA metabolites in relation to root stem cell growth were largely uncorrelated with ATP levels.11 This suggests that, unlike many metabolic processes typically linked to ATP production, TCA metabolites may have roles that extend beyond basic energy maintenance. Specifically, these metabolites appear to play additional, localized, non-canonical roles in regulating different stages of root development outside of those tied to energy production, further supporting the hypothesis that TCA metabolites help the plant modulate growth in specific developmental contexts outside of only metabolism. Understanding these metabolite concentrations can help us identify the key factors needed to grow deeper roots, essential for improving plant resilience, and provide a pathway into engineering plant roots able to survive in the face of climate change.
Ultimately, the hope is to maintain food security despite a rapidly changing climate, especially for staple grains like maize, which play a major role in global food systems. Food security could be severely exacerbated unless research is accelerated to address the negative impacts of environmental change on agriculture. The research conducted by Dr. Alexandra Jazz Dickinson’s Lab offers promising pathways for a sustainable agricultural future. By studying the TCA cycle, which is conserved across a wide variety of plant types, the lab’s work aims to enhance crop resilience better withstand drought stress and other climate-related challenges.11 Human activities have caused the climate warming which has inflicted stress upon agricultural crops. However, with research geared towards exploring plant growth and development, it may also be human involvement through science that helps us enrich sustainable crop production, ensuring that our grocery shopping runs remain as accessible and affordable as possible.
Sources:
Agriculture and rural development. World Bank. (n.d.). https://www.worldbank.org/en/programs/knowledge-for-change/brief/agriculture-and-rural-development
Growing threats: How climate change will exacerbate agriculture’s impacts. The Nature Conservancy. (n.d.). https://www.nature.org/en-us/newsroom/growing-threats-how-climate-change-will-exacerbate-environmental-impacts-agriculture/
Yang, Y., Tilman, D., Jin, Z., Smith, P., Barrett, C. B., Zhu, Y.-G., Burney, J., D’Odorico, P., Fantke, P., Fargione, J., Finlay, J. C., Rulli, M. C., Sloat, L., Jan van Groenigen, K., West, P. C., Ziska, L., Michalak, A. M., Lobell, D. B., Clark, M., … Zhuang, M. (2024). Climate change exacerbates the environmental impacts of Agriculture. Science, 385(6713). https://doi.org/10.1126/science.adn3747
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NCEI.Monitoring.Info@noaa.gov. (n.d.). June 2024 global climate report. June 2024 Global Climate Report | National Centers for Environmental Information (NCEI). https://www.ncei.noaa.gov/access/monitoring/monthly-report/global/202406#:~:text=The%20average%20temperature%20of%20the%20contiguous%20U.S.%20for%20the%20January,on%20record%20for%20this%20period
Kim, K.-H., & Lee, B.-M. (2023). Effects of climate change and drought tolerance on maize growth. Plants, 12(20), 3548. https://doi.org/10.3390/plants12203548 Environmental Protection Agency. (n.d.). EPA.
Feed grains sector at a glance. USDA ERS – Feed Grains Sector at a Glance. (n.d.). https://www.ers.usda.gov/topics/crops/corn-and-other-feed-grains/feed-grains-sector-at-a-glance/
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Zhang, T., Noll, S. E., Peng, J. T., Klair, A., Tripka, A., Stutzman, N., Cheng, C., Zare, R. N., & Dickinson, A. J. (2023). Chemical Imaging reveals diverse functions of tricarboxylic acid metabolites in root growth and development. Nature Communications, 14(1). https://doi.org/10.1038/s41467-023-38150-z
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