二倍体和四倍体杂交兰幼苗对低温胁迫的生理响应差异分析

为探究不同倍性杂交兰（Cymbidium hybrid）对低温胁迫的生理响应差异,对低温胁迫下（昼温10℃、夜温4℃）二倍体杂交兰以及四倍体杂交兰株系T1和T2幼苗叶片中脯氨酸、可溶性糖、可溶性蛋白质、MDA和叶绿素含量,O-·2产生速率以及SOD、POD和CAT活性的动态变化进行了测定和分析;在此基础上,比较了二倍体和四倍体杂交兰的耐低温特性差异。结果显示：随着胁迫时间的延长,二倍体杂交兰和四倍体杂交兰株系T1和T2幼苗叶片中脯氨酸、可溶性糖、可溶性蛋白质和MDA含量,O-·2产生速率以及POD和CAT活性总体呈逐渐增加的趋势;叶绿素含量呈逐渐下降的趋势;SOD活性呈先上升后下降的趋势,并分别在胁迫后第9天和第6天达到峰值。在常温（25℃）下恢复生长3d后,二倍体杂交兰和四倍体杂交兰株系T1和T2幼苗叶片中脯氨酸、可溶性糖、可溶性蛋白质和MDA含量,O-·2产生速率以及SOD、POD和CAT活性均降低,而叶绿素含量升高。总体上,二倍体杂交兰叶片中脯氨酸、可溶性糖和可溶性蛋白质含量以及SOD、POD和CAT活性的增幅明显小于四倍体杂交兰,MDA含量和O-·2产生速率的增幅则大于四倍体杂交兰,而叶绿素含量的降幅则明显大于四倍体杂交兰。综合分析结果表明：在低温胁迫下,四倍体杂交兰叶片中渗透调节物质含量和保护酶活性均较高,其对低温的耐性强于二倍体杂交兰。

Analysis on difference in physiological response of diploid and tetraploid of Cymbidium hybrid seedling to low temperature stress

To inquire into difference in physiological response of Cymbidium hybrid with different ploidies to low temperature stress,dynamic changes in contents of proline,soluble sugar,soluble protein,MDA and chlorophyll,O-·2production rate and activities of SOD,POD and CAT in seedling leaf of diploid of Cymbidium hybrid and tetraploid strains T1 and T2 of Cymbidium hybrid under low temperature stress（ day temperature 10 ℃,night temperature 4 ℃） were determined and analyzed. On this basis,difference in tolerance of diploid and tetraploid of Cymbidium hybrid to low temperature was compared.The results show that with prolonging of stress time,contents of proline,soluble sugar,soluble protein and MDA,O-·2production rate and activities of POD and CAT in seedling leaf of diploid of Cymbidium hybrid and tetraploid strains T1 and T2 of Cymbidium hybrid totally appear gradually increasing trend,chlorophyll content appears gradually decreasing trend,and SOD activity appears the trend of firstly increasing and then decreasing and reaches the peak value on the 9th and 6th days of stress,respectively. On the 3rd day of recovery growth under normal temperature（ 25 ℃）,contents of proline,soluble sugar,soluble protein and MDA,O-·2production rate and activities of SOD,POD and CAT in seedling leaf of diploid of Cymbidium hybrid and tetraploid strains T1 and T2 of Cymbidium hybrid all decrease,while chlorophyll content increases. In general,in seedling leaf of diploid of Cymbidium hybrid,increasing ranges of contents of proline,soluble sugar and soluble protein and activities of SOD,POD and CAT are obviously lower and those of MDA content and O-·2production rate are higher than those of tetraploid of Cymbidium hybrid,while decreasing range of chlorophyll content is obviously higher than that of tetraploid of Cymbidium hybrid. The comprehensive analysis result shows that both osmoregulation substance content and protective enzyme activity in leaf of tetraploid of Cymbidium hybrid are higher and its tolerance to low tempera