[Free amino acids, stem type and revolutive activity of the stems in Periploca graeca L]

Among the species P. graeca L. the fast-growing long types of shoots (twining and creeping) contain a large amount of amino acids (from 65 to 50 micromoles per gram of fresh weight), the dominant acid being glutamic acid. The slow growing short shoots have a lesser content of amino acids (30 micromoles per gram of fresh weight) dominated by aspartic and glutamic acids.The tips of the twining shoots are distinguished from those of the creeping shoots by a high proline level (20% of the total amino acid content against 5%). In the early development, when the morphological differentiation is not yet complete, twining shoots have a free amino acid content in which proline is abundant.The relationship between the high proline level and the revolutive movement is shown by the results of analyses of short stems made to twine by the tratment with gibberellic acid. Proline is abundant only in the tissues possessing the ability of circumnutation.