不同地理种源红砂幼苗对PEG胁迫的生理响应

以兰州、武威、张掖、酒泉4个地理种源红砂幼苗为试材,研究了不同浓度PEG胁迫对红砂叶片的质膜透性、保护酶活性和渗透调节物质等生理指标的影响。结果表明,不同地理种源红砂的脯氨酸(Pro)含量和可溶性糖(SS)含量均随胁迫浓度的增加而呈先上升后下降的趋势,武威种源渗透调节物质累积较其他种源的多。丙二醛(MDA)含量和质膜透性均随胁迫浓度的增加呈上升趋势,但武威种源增加幅度最小,说明武威种源红砂的组织受伤害较小,抵御干旱的能力较其他3个种源强。活性氧清除酶类(SOD,POD,CAT)活性均是先升高后降低的趋势,武威种源红砂始终比其他3个种源保持较高的POD和CAT活性。但在胁迫状态下植物体内保护酶对体内活性氧的清除能力有一个阈值,超过此阈值,则保护酶活性下降。相关性结果表明,4个地理种源红砂的细胞膜透性与MDA含量呈正相关,与游离Pro和可溶性糖呈极显著正相关(P＜0.01),与酶活性呈负相关。通过综合分析发现, 4个地理种源红砂的抗旱能力依次为:武威种源>酒泉种源>张掖种源>兰州种源。

Physiological responses to PEG stress of Reaumuria soongorica seedlings from different geographical origins

The effects of different concentrations of PEG-6000 stress on relative permeatbility of plasma membrane, protective enzyme activity, and osmotic gulatory molecules in leaves of Reaumuria soongorica seedlings from Lanzhou, Wuwei, Zhangye and Jiuquan geographic origins in Gansu province were studied. Contents of proline (Pro) and soluble sugars (SS) in leaves initially increased but then decreased as the stress concentrations increased. The accumulation in plants from Wuwei was more than that in those from other origins. Contents of malondiadehyde (MDA) and relative permeability of plasma (RPP) increased as stress concentrations increased but the increased range in Wuwei origin plants was less than that of others, which indicated a stronger drought resistances than plants from the other origins. Protective enzyme activities such as superoxide dismutase (SOD), peroxide enzyme (POD) and catalase (CAT) increased initially but then decreased. POD and CAT activities of Wuwei origin plants were higher than those from other origins. There was a threshold of protective enzyme activity, and it was reduced when protective enzyme activity was out of the threshold level. Correlation analysis showed that there were significant positive correlations of relative permeability of plasma with MDA (P＜0.05), highly significant positive correlations with Pro and SS (P＜0.01), and significant negative correlations of relative permeability of plasma with SOD, CAT, and POD activity (P＜0.05). Drought resistance of R. soongorica from four geographic origins was in the following order Wuwei>Jiuquan>Zhangye>Lanzhou.