两个海拔分布下红砂叶片对渗透胁迫的生理响应

探讨了2个海拔分布红砂叶片对渗透胁迫的生理响应的差别及其机制,结果表明,在渗透胁迫逐渐加强的条件下,山下的红砂叶片持水力较强,渗透调节物质含量较高,活性氧水平和脂质过氧化产物丙二醛含量较低,可见山下红砂叶片耐渗透胁迫的能力强于山上的红砂;渗透胁迫下红砂各项生理指标变化的相关性分析显示,叶片相对含水量、水势及自由水/束缚水均与MDA含量、O₂^-·产生速率显著负相关, SOD活性与O₂^-·产生速率呈显著正相关。可见,对于九州台山上和山下生长的2组材料,在PEG胁迫加深的条件下,山下的红砂叶片具有较强的渗透调节能力和抗氧化能力,脂质过氧化的水平也较低,产生这些生理响应差别的主要因素可能为2组材料水分状况的不同,即山下红砂叶片束缚水含量较高,在深度胁迫下的保水性较好,且在通常情况下山下红砂叶片较低的相对含水量和水势也可能是其抗渗透胁迫能力较强的重要原因。

Physiological responses in leaves of Reaumuria soongorica from different altitudes under osmotic stress

The different physiological responses and their mechanisms in the leaves of Reaumuria soongorica from two altitudes when under osmotic stress were studied. When the leaves of R. soongorica were seriously stressed, the leaves from the branches picked at the foot of the Jiuzhoutai mountain had a better water condition, higher contents of proline and soluble sugar, lower malondialdehyde (MDA) content and reactive oxygen level. The materials living at the foot of the mountain were better in hardness than those living on the top of the mountain. The interrelationship analysis among the above indexes showed that there were significantly negative relationships between the relative water content, water potential, the ratio of free water content with bound water content and MDA content, and O₂^-· production rate, and there was a significantly positive relationship between superoxide dismutase (SOD) activities and O₂^-· production rate. With an increase of osmotic stress, the material living at the bottom had better osmoregulation and antioxidative ability, and even lower level of lipid-oxidation. The main reason for the above differences may be the water content: the material living at the bottom of the mountain had higher levels of bound water, and better water retaining ability under deep osmotic stress. The relatively lower water content and water potential of the material living at the bottom could be one of the important reasons for the better osmo-regulation ability to deal with osmotic stress.