Highly expressed genes in the foliage of giant leucaena (Leucaena leucocephala subsp. glabrata), a nutritious fodder legume in the tropics

Giant leucaena (Leucaena leucocephala subsp. glabrata) is an arboreal tree legume, which is widely grown as a source of high-protein fodder for animals. The goal of this research was to identify genes that are highly expressed in the foliage so that the yield and nutritional value of the foliage can be further enhanced in giant leucaena grown for fodder. Through microarray analysis of 10,000 cDNA, based on a transcriptome library of giant leucaena, 138 gene sequences were identified to be expressed highly in the foliage compared with the root. Quantitative real-time polymerase chain reaction analysis validated the expression of 13 genes selected from the most highly expressed sequences in the foliage. These genes encoded proteins involved in the metabolism of starch, lipids, cell wall components and secondary metabolites such as β-amyrin and mimosine. Long-chain acyl-CoA synthetase and mimosinase are two of the most highly expressed genes in the foliage. Mimosinase is involved in recycling mimosine, which may be a storage molecule that is degraded to produce substrates for synthesis of amino acids and other metabolites. Some of the highly expressed genes identified in this study can be used in future breeding programs for enhancing fodder yield and quality of giant leucaena.