Mimosine is a stress-response molecule that serves as both an antioxidant and osmolyte in giant leucaena (Leucaena leucocephala subsp. glabrata) during environmental stress conditions

Abstract

• Mimosine content decreases in plants exposed to prolonged drought and flood stress. • Mimosine content increases in plants that are supplied with combined nitrogen. • Mimosine production was most favorable at neutral pH. • Mimosine has antioxidant and osmotic properties. Giant leucaena ( Leucaena leucocephala subsp. glabrata ) contains large amounts of a non-protein amino acid, mimosine. To study the possible role of mimosine in stress tolerance, the mimosine content was characterized in giant leucaena seedlings exposed to normal and various stress conditions. The relative osmotic and antioxidant properties of mimosine were also characterized. The mimosine contents of the seedlings were directly correlated with the amounts of available nitrogen supplied to the plants. During prolonged drought and flood stress, the mimosine content of leucaena decreases. The seedlings produced the highest amounts of mimosine at neutral pH, but mimosine production was reduced at both lower and higher pH values. It was shown that mimosine has some radical scavenging and osmotic properties. Although compared to other known antioxidants and osmolytes in plants, mimosine has minor effects, but because of its presence in large quantities in giant leucaena, its combined effects may be substantial. Thus, mimosine appears to be a stress response molecule that is produced in large amounts in giant leucaena under favorable growth conditions and utilized as a source of carbon and nitrogen during stress conditions when the nutrient availability becomes scarce.