关键词: 多浆旱生植物, 少浆旱生植物, 中旱生植物, 游离氨基酸, 游离脯氨酸, 阿拉善荒漠, 渗透调节, 干旱

Abstract: The distribution characteristics of free amino acids and free proline were investigated in succulent xerophytes—Haloxylon ammodendron and Zygophyllum xanthoxylum, xerophytes—Artemisia sphaerocephala and Caragana korshinskii; and mesophytes Agriophyllum squarrosum and Corispermum mongolicum in Alxa Desert of China. The results showed that the content of total free amino acids were lowest in roots, and highest in leaves. The chief composition of amino acids was different in all of species; the chief composition of amino acids was different in different position, even if in the same species. Xerophytes accumulated large quantities of free proline; the proline concentrations in whole plant were 6.0- to 16.0-fold higher than those of the mesophytes, and were 1.8- to 25.0-fold higher than those of H.ammodendron and Z.xanthoxyluma. In A.sphaerocephala, the concentrations of total free amino acids increased by 2.0- and 5.7-fold, and the concentrations of free proline increased by 3.0- and 10.5-fold from roots to stems, and from stems to leaves, respectively. A similar trend was observed in C.korshinskii. Therefore, accumulating free proline may play a role in drought adaptation in xerophytes. The concentrations of total free amino acids only had a few increased in succulent xerophytes and mesophytes, and it was free proline accumulation that was not the most important factor. Thus succulent xerophytes and mesophytes did not mainly depend on accumulating free proline to adapt to arid environments.

Key words: succulent xerophytes, xerophytes, mesophytes, free amino acids, free proline, Alxa Desert, osmot ic adjustment, drought