阿拉善荒漠区几种抗旱植物游离氨基酸和游离脯氨酸的分布特征

Distribution Characteristics of Free Amino Acids and Free Proline in Sseveral Drought-resistant Plants of Alxa Desert, China

以阿拉善荒漠区生长的多浆旱生植物梭梭(Haloxylonammodendron)和霸王(Zygophyllumxanthoxy lum)、少浆旱生植物白沙蒿(Artemisiasphaerocephala)和柠条(Caraganakorshinskii)、中旱生植物沙米(Agrio phyllumsquarrosu)和绵蓬(Corispermummongolicum)为材料,对其游离氨基酸成分及游离脯氨酸的分布特征进行了比较研究。结果表明,供试植物根中的总游离氨基酸含量均低于茎和叶中的总游离氨基酸含量,其中叶中的游离氨基酸总量最高;不同植物中的主要氨基酸组成不相同,同一植物的不同部位主要氨基酸组成也不尽相同。少浆旱生植物体内大量积聚游离脯氨酸,其整株中的游离脯氨酸是中旱生植物的6 0～16 0倍,是多浆旱生植物的1 8～25 0倍。白沙蒿植株的根到茎、茎到叶,总游离氨基酸含量以2 0倍和5 7倍的增幅增加,其中游离脯氨酸含量增加最明显,增幅达3 0倍和10 5倍。柠条植株也表现出同样的趋势。可见,大量积累游离氨基酸,特别是游离脯氨酸是少浆旱生植物适应干旱荒漠生境的重要机制。从根到茎、由茎到叶,中旱生植物沙米和绵蓬与多浆旱生植物梭梭和霸王总游离氨基酸含量增幅都并不十分显著;二者中的游离脯氨酸积累不占主导地位。故中旱生植物和多浆旱生植物并不主要依靠积累脯氨酸来调节渗透势确保水分的供应。

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.