Diverse Tobacco Organs Respond Differently to Stress

16:13, January 9, 2024

University biologists tested the plants extensively and reached this conclusion

The biologists at Ural Federal University have discovered that various parts of the tobacco plant, such as leaves, roots, and stems, react differently to stress induced by prolonged exposure to copper ions. The acclimatization of the root and stem to stress differs from that of the leaves. Prolonged stress causes tobacco to increase the synthesis of phenylpropanoid compounds, which are essential for constructing lignin, resulting in the woodiness of the root and stem. The accumulation of copper in the root strengthens and thickens it, limiting the transportation of copper to the stem and leaves. This process of tobacco adaptation to long-term stress was described in the International Journal of Molecular Science. The Russian Science Foundation supported the study (project No. 22-24-00817).

"Our work aims to determine what metabolic and biochemical changes occur in different organs of tobacco during acclimation to prolonged exposure to copper ions. Typically, laboratory studies focus on short-term stress, while plants in nature adapt to long-term stress. It is important to note that plants activate different defense mechanisms under short-term and long-term stress conditions. Therefore, this study focuses on the later reactions of plants. We found out how the spectrum of phenolic compounds, which are precursors of lignin, changes," says Anastasia Tugbaeva, Senior Lecturer at the Department of Experimental Biology and Biotechnologies of the UrFU.

Understanding additional mechanisms and defense reactions during prolonged stress can aid breeders in cultivating resilient potatoes, tomatoes, and eggplants. This knowledge is not only applicable to Russia but also to countries such as Brazil, Chile, China, and Australia where the mining industry is prevalent, and copper contamination of soils is widespread. Furthermore, agricultural activities, such as the use of copper-based fungicides, contribute to copper contamination of soils. This issue is relevant, for instance, in agricultural soils in France and Italy.

"The results of our work can be used in plant protection and breeding - we have confirmed the effectiveness of biochemical markers for identifying plants resistant to stress. The effectiveness of biochemical markers in identifying stress-resistant plants was confirmed, as was the universality of the mechanism of plant shoot hardening (wooding) in response to abiotic stress," adds Alexander Yermoshin, Associate Professor of the Department of Experimental Biology and Biotechnology at the UrFU.

According to the biologist, plants frequently undergo stress. However, they may activate specific mechanisms that enable them to survive or fail to adapt and ultimately perish.

In the experiment, biologists subjected tobacco to controlled stress conditions and monitored its response to prolonged exposure to copper ions. The study examined the effects of two doses of copper ions, 100 and 300 μm, on tobacco for 40 days. As a result of the treatment, the amount of copper in the root increased by 23 and 26 times, respectively, while the increase in the stem and leaves was insignificant. At a dosage of 100 μm, the amount of copper increased by 2 and 2.8 times in the stem and leaves, respectively. At a dosage of 300 μm, the increase was 3 and 3.5 times, respectively. At lower dosages, the plant successfully adapted and even slightly increased its total mass, with a 16 percent increase in height and a 13 percent increase in leaf area. However, at higher dosages, tobacco began to develop oxidative stress and negative effects that the plant could not fully adapt to.

"Research on the effects of various stressors on plants is viral today. Soil contamination and increasing yields of crops are also relevant due to the growing global population. Therefore, we are on the cutting edge of physiological research," says Alexander Yermoshin.

Reference

Lignin is a complex polymeric compound found in the cell walls of plants. For instance, the bark of trees contains 20-30 percent lignin. Lignin enables trees to maintain their upright position and effectively resist external influences - wind, precipitation, and harmful organisms. Additionally, tobacco is a herbaceous plant. As a result of stress, the root and stem cell walls become more woody.

Anna Marinovich, Sergey Lukyanchenko

The news article was translated by UrFU International Marketing Office.
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