Influence of lead pollution on the growth, development, and metabolism of cereal crops: the protective role of salicylic acid

Cereal crops are the world's main source of food.They provide more than half of the world's total calorie needs.Sustainable access to quality cereals is important in addressing food security challenges.Soil contamination with lead (Pb) seriously threatens sustainable cereal production.In Ukraine, this problem has become particularly acute due to the intense hostilities.By inhibiting important functional groups in proteins, displacing critical metal ions, and accumulating reactive oxygen species, lead, a non-essential heavy metal, has a complicated harmful effect on plant organisms.According to studies, lead considerably reduces the germination of seeds and the growth of cereal seedlings; the degree of this effect varies according to the concentration, length of exposure, and type of plant.At high concentrations of Pb, seed germination decreases by 30-40 %, root length decreases by 45 %, and the stress resistance index decreases significantly.At the cellular level, Pb disrupts the structure and functions of photosystems, causes oxidative stress, destabilizes membranes, and loses the integrity of cellular organelles.Salicylic acid (SA), a phenolic plant hormone, plays a key role in the regulation of numerous plant physiological processes, including growth and development, photosynthesis, respiration, transpiration, and provides for the formation of defense responses, increasing the resistance of cereals to a wide range of abiotic and biotic stressors.The SA plays a special role in shaping the resistance of cereals to Pb contamination through its participation in the transmission of stress signals, antioxidant defense mechanisms and modulation of physiological processes.In this review, we present a contemporary summarization of existing data on the impact of Pb toxicity on morphophysiological and biochemical responses of major cereal crops.We also highlight the data on the mechanisms of lead ion uptake and translocation in plants, critically discuss possible strategies for phytoremediation of soils and ways to overcome the threat of lead toxicity for cereals.