RUDN agronomists save bamboo from toxic lead using a phytohormone cocktail

Lead contaminates fertile soils. RUDN University agronomists have proven that phytohormones mitigate the consequences of soil contamination with lead. These phytohormones are produced by the plants themselves, but additional soil treatment helps to better cope with the toxic effects of the metal. The results were published in Environmental Science and Pollution Research.

Newswise — Heavy metals are dangerous not only to human health but also to agriculture. Heavy metals slow down crop growth and reduce yields. The second most common heavy metal is lead. It is used in the production of paints, glass, and batteries. Once lead enters the soil with waste, it quickly infects plants. Heavy metal provokes the appearance of aggressive oxidizing agents that destroy plant cells - causing oxidative stress. RUDN University agronomists and colleagues from China, Pakistan, Saudi Arabia, the USA, and Turkey found that phytohormones—substances produced by plants that regulate processes within them—can mitigate the toxic effects of lead.

“Phytohormones, also known as plant signaling agents, regulate plant metabolism and internal development processes, for example, serving as chemical mediators in various cellular processes. These small molecules are present in low concentrations in plants. It is already known that phytohormones are also involved in the response of plants to stress. This provides a potential opportunity to manipulate the level of stress from heavy metal contamination,” Meisam Zargar, Doctor of Agricultural Sciences, Associate Professor of the RUDN University Agrobiotechnological Department said.

Agronomists experimented with a “cocktail” of two groups of phytohormones - jasmonates and brassinosteroids. The first, including jasmonic acid and its esters, regulate the growth and development of plants. The second - stress hormones with strong growth-stimulating activity - support the immune system, especially under unfavorable conditions. Agronomists planted bamboo shoots 10 mm long and treated the soil with jasmonates and brassinosteroids, together and separately. Along with phytohormones, lead was added to the soil in different quantities - from 0 to 150 micromoles.

The phytohormone cocktail significantly improved bamboo growth and resilience by reducing oxidative stress. The content of active oxidizing agents, the appearance of which was caused by lead, has decreased. For example, the amount of hydrogen peroxide decreased by 33%. At the same time, the activity of substances responsible for the antioxidant response increased by 14–20%.

“The mixture of jasmonates and brassinosteroids markedly reduced oxidative stress in bamboo. In addition, this treatment increased the resistance of plants by increasing the activity of enzymes, the ability of plants to “neutralize” metals, and more active growth. This also reduces the potential danger of heavy metal to the environment. In the future, we can study the effect of types of phytohormones on different types of bamboo or other plants,” Meisam Zargar, Doctor of Agricultural Sciences, Associate Professor of the RUDN University Agrobiotechnological Department said.