兴安鹿蹄草(Pyrola dahurica (H.Andr.) Kom.)雪盖前后丙二醛及渗透调节物质含量的变化

研究了自然生境下生长的兴安鹿蹄草(Pyrola dahurica(H.Andr.)Kom.)根状茎及叶片中渗透调节物质、膜脂过氧化产物在雪盖前后的变化。结果表明,在雪盖前期(10月1日～12月15日)兴安鹿蹄草根状茎及叶片中丙二醛(MDA)含量先增高,尔后下降,翌年春季雪盖后期(3月1日～4月15日)MDA含量明显低于雪盖前期,雪盖前期根状茎的丙二醛(MDA)含量低于叶片,雪盖后期高于叶片。可溶性糖、可溶性蛋白质含量在雪盖前期随着温度的下降而升高,11月中旬达到最大,尔后下降,脯氨酸含量先下降尔后升高。雪盖后期渗透调节物质含量高于雪盖前期,可溶性糖含量随气温的升高而下降,可溶性蛋白质与脯氨酸含量随气温升高而大幅度升高,而且成明显正相关。根状茎的可溶性糖含量在雪盖前期、雪盖后期低于叶片,可溶性蛋白质与脯氨酸含量在雪盖前期、雪盖后期高于叶片。兴安鹿蹄草主要通过渗透调节物质含量的变化来适应雪盖前期及雪盖后期低温环境而安全越冬。

Changes in contents of MDA and osmoregulatory substances during snow cover for Pyrola dahurica

The Pyrola dahurica,an indicator of mixed conifer broad-leaved forest,is an important medicinal species in northeastern China.The mechanism of cold hardiness for this evergreen species is not well known.To explore its cold hardiness during winter seasons,we measured contents of MDA and osmoregulatory substances(i.e.soluble sugar,soluble protein and proline) in the rhizomes and leaves of Pyrola dahurica in two stages:early stage of snow cover(ESSC:from October to December in 2005) and late stage of snow cover(LSSC:from March to April in 2006).The results showed that the MDA content increased at the beginning,and decreased gradually as the winter proceeded,suggesting that the degree of membrane injury decrease due to coldness conditioning.Compared with that in the leaves,the MDA content in rhizomes was lower in ESSC and higher in LSSC.The contents of soluble sugar and protein increased with the temperature decreasing in ESSC,peaked in the middle of November,and decreased afterwards;while that of proline presented an opposite trend.In the following spring as temperature was rising and snow melting,the contents of osmoregulatory substances(soluble protein and free proline) sharply increased,while the content of soluble sugar dropped gradually.The soluble protein content was strongly positively correlated to the free proline content.Whether in ESSC or in LSSC,the content of soluble sugar in rhizomes was lower than that in leaves,while the contents of soluble protein and proline in rhizomes was higher than those in leaves.We concluded that the Pyrola dahurica adapted low temperature winters by adjusting the contents of osmoregulatory substances in its leaves and rhizomes.