Mimosine concentration in giant leucaena (Leucaena leucocephala subsp. glabrata) fluctuates with age and plant part

Giant leucaena is a multipurpose tree-legume found throughout the tropics and sub-tropics. Its foliage is used as animal fodder due to high protein and fiber. Giant leucaena has several other advantageous traits such as fast-growth, high yields and strong tolerance to environmental stresses. Despite having these desirable qualities, leucaena tissues contain an undesirable attribute, a toxic non-protein amino acid, mimosine, found in all parts of the plant including the foliage. The goal of this research was to determine mimosine concentrations in various tissues and life stages of giant leucaena plants to inform use of leucaena foliage as a fodder. Mimosine was extracted from different parts of giant leucaena at different ages and quantified using HPLC analysis. qRT-PCR was used to determine the relative expression of mimosine synthase in leucaena tissues. Mimosine was present in all parts of the leaf, stem and root of giant leucaena, and concentrations changed depending on the age of the plant. Green seeds had the highest expression level of mimosine synthase. Mimosine is ubiquitous and abundant in leucaena tissues with younger and immature plants and tissues containing more mimosine than older mature plants and tissues.