Amino Acid Content in Rhododendron schlippenbachii Maxim. Flowers of Different Colors

摘要

Rhododendron is one of the largest shrubs and is well known as a garden plant because of their evergreen leaves and various flower colors. The present study investigated the variation in amino acids in the differently colored flowers of Rhododendron schlippenbachii. Analysis of the Rhododendron flowers revealed 22 types of amino acids. The amino acid content varied greatly depending on the different colors of the flowers. Violet Rhododendron flowers had the highest total quantity of amino acids, which was 2.24 and 1.31 times higher than the total amino acid content in the red and white flowers, respectively. Violet Rhododendron flowers also contained the highest quantities of aspartate, glutamate, glutamine, histidine, ~3-aminobutyric acid (GABA), and methionine while white Rhododendron flowers contained the highest quantities of serine, threonine, alanine, valine, norvaline, tryptophan, phenylalanine, isoleucine, and leucine. Compared to the violet flowers, white flowers had 1.24, 1.35, 2.34, and 2.46 times higher amounts of serine, tryptophan, phenylalanine, isoleucine, and leucine, respectively. Although the total amino acid content was the lowest in the red flowers, these flowers contained the highest quantities of Asparagine, Vitamin U, Glutamine, Glycine, Tyrosine, Cysteine, and Lysine. The content of Asparagine was much higher in red flowers than in any other color of Rhododendron flower. Red flowers contained 3.70 and 2.48 times higher levels of asparagine than that measured in white and violet colored Rhododendron flowers, respectively. Our results demonstrate that Rhododendron flowers with different colors contain variable quantities of amino acids, with the highest total amount of amino acids observed in the violet flowers.