Cold stress is the main abiotic stress that decreases the productivity of crops, and it has been proven to decrease the yield and quality of crops grown in cold regions. The most important effects of cold stress are on photosynthesis and respiration. The plants cannot take up sufficient carbon dioxide for photosynthesis, so they produce fewer carbohydrates, which leads to a decrease in plant growth and yield. Cold-stressed plants also have decreased respiration rates, reducing the energy available for growth or other physiological processes. Polyunsaturated fatty acids are a type of fat found in plants, and the non-enzymatic oxidation process causes these fats to produce reactive oxygen species. A study was conducted in order to investigate the effects of cold temperature stress on the lipid peroxidation process in plants. The researchers found that polyunsaturated fatty acids can undergo non-enzymatic oxidation to eliminate reactive oxygen species, and this oxidation process is triggered by cold temperature stress.
How Abiotic Stressors Will Impact Plants
Temperature Induced Stress
Source: Godoy et al., 2021
Figure 1. Abiotic stress is the environmental stress on plants and animals from factors other than climate, such as drought, salinity or extreme temperatures.
Water Availability
Plants can use a variety of mechanisms to cope with water-limiting conditions. One of the most important mechanisms is transpiration, a key process regulating the plant’s water balance. Transpiration can be described as the evaporation of water from plants and their leaves. This process is driven by the difference in water pressure between the inside and outside of the leaf (the osmotic gradient). Some plants use other mechanisms to regulate their water balance, such as stomata closure, leaf withering, and leaf senescence. These all have some effect on transpiration, but they are less effective than transpiration at limiting water loss. In plants, lipid signaling molecules play a crucial role in regulating the water. Lipid signaling molecules are involved in the regulation of water by controlling the osmotic potential of cells.
Osmotic Stress
Plants can sense osmotic stress and respond to it. Osmotic stress is when the plant cells cannot produce enough osmolytes, like sugars and amino acids, to balance the water that enters the cell. This can happen because of drought or salt stress. The plant will then activate a series of responses to maintain turgor pressure and keep the cell from collapsing. Some responses include closing stomata, reducing growth rate, producing more sugar for storage in vacuoles, and activating genes that help cells transport water from the roots up into leaves. Lipid signaling is an integral part of the adaptation of plants to saline environments. Plant lipids are very important in coping with salt and osmotic stress. To cope with osmotic stress, plants have to adjust their metabolism. They do so by inducing changes in root architecture and cytoskeletal organization.
Source: Lohani et al., 2020
Figure 2. The physiological impact of abiotic stresses on different developmental stages in canola has been studied. A study by Lohani et al (2020) was conducted to determine the physiological impact of multiple abiotic stresses in canola, and to elucidate the underlying mechanisms. The results show that multiple abiotic stresses have a negative effect on seedling growth, photosynthesis and chlorophyll content, which ultimately influences plant height. These findings suggest that the physiological performance of canola seedlings decreases with increasing number of abiotic stresses.
Heavy Metals
Plants are exposed to various elements and chemicals throughout their growth cycles. Some plants have the ability to accumulate hazardous metals and metalloids such as arsenic, cadmium, and aluminum. The compounds can be found in soils and water sources due to industrial activities or agricultural runoff. Plants are also exposed to these substances through airborne deposition or contact with contaminated dust particles. Metals and metalloids can enter cells through any of the plant’s major pathways, and in many cases, these substances are toxic to plant cells. Once in the cell, metal ions are generally taken up by a specific transport protein called a solute carrier family transporter (SFT), which recognizes metals with similar charges. SFTs can transport metals away from the nucleus or into it depending on their charge and other properties. SFTs take up metals with a net positive charge on their surface and release those with a negative charge. The presence of heavy metals in the soil can have adverse effects on plants, such as stunting their growth or even killing them. These metals are found in many agricultural products, such as fertilizers and pesticides. One option to avoid these adverse effects is to plant less sensitive crops to heavy metals. However, only a few crops are resistant to these metals, so this only sometimes not always possible. Another possibility is removing excess fertilizers from the soil before planting the next crop. This can be done through a process called leaching or by using a cover crop.
Laboratory Testing for Indicators of Plant Stress
Genetic analysis of crops is a common technique for identifying the presence of hazardous metals and metalloids. Some plants can accumulate these toxic substances from the soil and water. For example, vegetables grown on contaminated soils can accumulate lead. The worldwide use of chemicals in agriculture has led to a new class of contaminants called “adventitious agents” (i.e., substances that are not usually present in the soil but enter it during crop production). These substances are commonly found in crops and may accumulate at high concentrations over time. For example, zinc (Zn) is an element present at low soil levels but can have high concentrations when plants absorb it.
Apical has developed a spectroscopy technique using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) to identify the presence of toxic metals and metalloids in plants, soil, and water. Using this method, Apical can detect low levels of these toxic metals and metalloids with great accuracy. ICP-OES is also advantageous because it requires a simple sample preparation before the sample is ready for analysis. This process can be helpful for farmers who want to know which fertilizers they should use. Farmers who over-fertilize their crops are putting themselves at risk for high levels of arsenic, cadmium, and aluminum in the soil.
Further Reading
Blancaflor, E. B., Kilaru, A., Keereetaweep, J., Khan, B. R., Faure, L., & Chapman, K. D. (2014). n-acylethanolamines: Lipid metabolites with functions in plant growth and development. The Plant Journal, 79(4), 568–583. https://doi.org/10.1111/tpj.12427
Darwish, E., Testerink, C., Khalil, M., El-Shihy, O., & Munnik, T. (2009). Phospholipid signaling responses in salt-stressed rice leaves. Plant and Cell Physiology, 50(5), 986–997. https://doi.org/10.1093/pcp/pcp051
Durand, T., Bultel‐Poncé, V., Guy, A., Berger, S., Mueller, M. J., & Galano, J. M. (2009). New bioactive oxylipins formed by non‐enzymatic free‐radical‐catalyzed pathways: The phytoprostanes. Lipids, 44(10), 875. https://doi.org/10.1007/s11745-009-3351-1
Finka, A., Cuendet, A. F., Maathuis, F. J. M., Saidi, Y., & Goloubinoff, P. (2012). Plasma membrane cyclic nucleotide gated calcium channels control land plant thermal sensing and acquired Thermotolerance. The Plant Cell, 24(8), 3333–3348. https://doi.org/10.1105/tpc.112.095844
Hou, Q., Ufer, G., & Bartels, D. (2016). Lipid signalling in plant responses to abiotic stress. Plant, Cell & Environment, 39(5), 1029–1048. https://doi.org/10.1111/pce.12666
Lichtenthaler, H. K. (1996). Vegetation stress: An introduction to the stress concept in plants. Journal of Plant Physiology, 148(1-2), 4–14. https://doi.org/10.1016/s0176-1617(96)80287-2
Paes de Melo, B., Carpinetti, P. de, Fraga, O. T., Rodrigues-Silva, P. L., Fioresi, V. S., de Camargos, L. F., & Ferreira, M. F. (2022). Abiotic stresses in plants and their markers: A practice view of plant stress responses and programmed cell death mechanisms. Plants, 11(9), 1100. https://doi.org/10.3390/plants11091100
Rani, S., Kumar, P., & Suneja, P. (2021). Biotechnological interventions for inducing abiotic stress tolerance in crops. Plant Gene, 27, 100315. https://doi.org/10.1016/j.plgene.2021.100315
Spicher, L., Glauser, G., & Kessler, F. (2016). Lipid antioxidant and galactolipid remodeling under temperature stress in Tomato Plants. Frontiers in Plant Science, 7. https://doi.org/10.3389/fpls.2016.00167
Xu, L., Pan, R., & Zhang, W. (2020). Membrane lipids are involved in plant response to oxygen deprivation. Plant Signaling & Behavior, 15(7), 1771938. https://doi.org/10.1080/15592324.2020.1771938
Younis, A., Ramzan, F., Ramzan, Y., Zulfiqar, F., Ahsan, M., & Lim, K. B. (2020). Molecular markers improve abiotic stress tolerance in crops: A Review. Plants, 9(10), 1374. https://doi.org/10.3390/plants9101374
