Accumulation of proline and pattern of alpha-amino acids in sugar beet plants in response to osmotic, water and salt stress

Relative growth rate of sugar beets (Beta vulgaris L.) and the pattern of free amino acids were studied under different stress conditions. Osmotic and drought-induced stress resulted in a rapid increase in proline content while the growth rate of intact plants and Fresh weight of isolated leaf discs decreased. Salt stress also induced proline accumulation, but fresh weight was unchanged with treatment onset and increased with continuous incubation. The composition of free amino acids estimated by reversed phase high pressure liquid chromatography (HPLC) Tvas changed by different stress conditions. In contrast to aspartic and glutamic acids that were only slightly influenced by the stressor, the contents of acid amides and basic amino acids increased sharply. Most levels of the other free amino acids, except serine, were enhanced. The mechanism and importance of stress responses in sugar beet plants are discussed.