高寒山区牧草根中丙二醛、渗透调节物、多胺季节动态与抗冻力关系研究

温带地区的高山多年生草本植物可在－３０℃组织结冰状况下生存，然而人们并不了解其抗冻的生理机理。本研究目的拟通过测定自然生境下生长的４种高寒山区禾本科牧草（无芒雀麦（Ｂｒｏｍｕｓ ｉｎｅｒｍｉｓ Ｌｅｙｓｓ．）、花雀麦（Ｂｒｏｍｕｓ　 ｓｉｎｅｎｓｉｓ　 Ｋｅｎｇ．）、垂穗披碱草（Ｅｌｙｍｕｓ ｎｕｔａｎｓ Ｇｒｉｓｅｂ．）、草地早熟禾（Ｐｏａ ｓｐｈｙｏｎｄｙｌｏｄｅｓ　 Ｔｒｉｎ．）根中渗透调节物、膜脂过氧化产物、多胺含量季节变化，以了解他们与牧草抗冻的关系。结果表明，在晚秋（９月１～１５日）牧草根中ＭＤＡ含量增高，尔后下降，冬季保持恒定。总碳水化合物（ＴＮＣ），可溶性糖、脯氨酸、可溶性蛋白质含量随晚秋气温下降而增加，在１１月达到最高，尔后下降，且持续到翌年春季。随晚秋气温下降从９月到１１月根中多胺含量迅速增加，４种牧草平均增加１８０％，其中亚精胺（Ｓｐｄ）占多胺含量的５３％。在１１月牧草根中多胺几乎完全消失。上述物质在晚秋入冬增加正好与牧草抗冻锻炼时间相吻合，因而是植物抗冻适应的重要生理响应和植物越冬的低温保护物质。他们在降低细胞冰点、防止细胞结冰引起的膜机械伤害，抑制膜脂过氧化保护膜稳定性方面具有重要作用。

CHANGES IN THE ROOTS OF ALPINE GRASSES IN RELATION TO LATE FALL, WINTER AND SPRING FREEZING TOLERANCE

We assayed seasonal changes in lipid peroxidation and proline, protein, polyamine, TNC, soluble sugar and starch concentration in roots of four perennial forage grasses: Poa sphyondylodes Trin., Bromus inermis Leyss., B. sinensis Keng., and Elymus nutans Griseb. Our results showed though MDA levels remained relative constant over winter in live roots of all four species MDA levels in nearly dead leaves increased by 70% during late fall and rose by 28 % between September 1 and September 15. High root TNC and soluble sugar concentrations were observed in autumn for all species, but these then declined throughout winter and spring. Root soluble sugar, starch, soluble protein and proline concentrations increased by 86%, 14%, 70%, and 1000% respectively from September to November. During winter however, measured concentrations of these chemicals all declined. Root polyamines increased by 180% between September and October, one of which, Spd, had a high ratio to total polyamine pools. By November polyamine pools had decreased to levels too small to be detected. All measured cryoprotective substances accumulated in the roots of these forage grass species during winter hardening in autumn and then decreased gradually throughout winter and spring. These seasonal patterns were negatively correlated with temperature, and positively with winter hardening. Cryoprotective substances may supply nutrients to regrowing shoots in spring and contribute to the stabilization of the cell membrane by preventing lipid peroxidation and by binding the tissue water.