Tobacco alkaloid absorption induced bitterness in pea plants

Considering the potential ecological risks and food safety issues of tobacco alkaloid accumulation, this study builds upon the noted bitterness in the edible parts of the peas after their growth following continuous tobacco cropping. Based on previous study using peas as the research object, the field-measured values of six tobacco alkaloids with obvious soil accumulation trends were used to evaluate the allelopathic effects of various tobacco alkaloids. Tobacco alkaloids with the strongest allelopathic effects were selected as representative substances to study how they affected the growth, metabolism, and edible value of pea plants. Notably, mysomine had the strongest allelopathic effect. Relevant potential impact mechanisms were then further revealed through metabolome analysis. The pea plants absorbed tobacco alkaloids through the roots, transporting them upward in large amounts to the leaves and increasing their bitterness. The accumulation of tobacco alkaloids reduced the content of photosynthetic pigments in the pea leaves and caused oxidative damage to the cell membranes, reducing the content of sugar substances such as sucrose in the leaves. Under the stress of tobacco alkaloids, the hormone content of the pea plants increased, which stimulated the synthesis of flavonoids, terpenoids, and amino acids. This increased the source of bitter substances in the leaves, changing the structure of leaf nutrients and further aggravating the bitterness. By evaluating the allelopathic effects of different tobacco alkaloids on the growth of pea plants, the potential influence mechanism of tobacco alkaloids on their growth, metabolism, and quality was revealed. Finally, the potential risks of tobacco alkaloid residues on subsequent crop production and food safety were proposed, in order to provide a theoretical basis for the scientific evaluation of the allelopathic effects and optimal layout of crop planting systems in the future.