NaCl胁迫对白刺试管苗渗透调节物质及离子含量的影响

Osmosis-regulating Substance and Cation Contents in Nitraria sibirica Pall. Test-tube Plantlets with NaCl Stress

以西伯利亚白刺试管苗为材料,通过组织培养法研究了其在0、25、50、100和200mmol·L-1NaCl胁迫40d后的生长指标、有机渗透调节物质含量和Na+、K+、Ca2+、Mg2+离子含量的变化,以探讨其耐盐性.结果表明:(1)白刺试管苗地上部干重和根干重在50mmol·L-1NaCl胁迫下显著高于对照,而在100和200mmol·L-1NaCl胁迫下均显著低于对照.(2)随NaCl胁迫浓度增加,白刺试管苗叶片可溶性糖、脯氨酸含量和细胞质膜透性均呈持续上升趋势,叶片叶绿素含量和丙二醛含量分别呈先升后降、先降后升的趋势,并在50mmol·L-1NaCl处理时分别达到最高值和最低值.(3)随着NaCl处理浓度增加,白刺试管苗Na+含量和根系K+含量呈增加趋势且各处理均显著高于对照,幼苗Ca2+含量和地上部K+含量却呈减少趋势,而Mg2+含量较稳定;同时其Na+/K+、Na+/Ca2+和Na+/Mg2+随NaCl处理浓度增加而升高.研究发现,在低盐浓度(≤50mmol·L-1NaCl)胁迫下,白刺试管苗能积累Na+离子和有机渗透调节物质,在根系中维持较高水平的K+和Ca2+含量以及较低水平的Na+/K+和Na+/Ca2+比,以降低白刺细胞渗透势来适应盐渍环境,从而保持其较高的生长水平.

To study the salt-tolerance mechanism of Nitraria sibirica Pall. , we determined the growth parameters,osmosis-regulating substance contents and Na^＋, K^＋, Ca^2＋, Mg^2＋ cation contents of N. sibirica Pall. test-tube plantlets which have been growing for 40 d under 0,25,50,100,200 mmol·L^-1 NaCl stress. It showed that, under the stress of 50 mmol·L^-1 NaCl, shoot dry weight and root dry weight were significantly higher than the control. In contrast, under 100 and 200 mmol·L^-1 NaCl stress,biomass of N. sibirica Pall. test-tube seedlings is significantly lower than that of the control. With NaCI stress intensified, soluble sugar, free proline and cell membrane osmosis of N. sibirica Pall. test-tube plantlets gradually rose, but contents of chlorophyll increased first then decreased afterwards while the trends of MDA were opposite ; It is under 50 mmol·L^-1 NaC1 stress that the accumulation of chlorophyll ascend the highest and MDA descend the lowest value in the same condition. With increasing of NaCl concentration, Na^＋ content of N.sibirica Pall. test-tube plantlets and K^＋ in root went up continuously,which were significantly higher than that of the control respectively. Ca^2＋ content in whole N. sibirica Pall. test-tube plantlets and K^＋ content in shoot decreased but the content of Mg^2＋ was stable, Na^＋/K^＋ , Na^＋/Mg^2＋ , Na^＋/Ca^2＋ increased accordingly N. sibirica Pall. test-tube plantlets under low NaCl concentration （≤50 mmol·L^-1）may adapt to salt environment by accumulating Na^＋ ,osmosis-regulating substances, high K^＋ and Ca^2＋ contents and decreasing Na^＋/K^＋ and Na^＋ /Ca^2＋ in root.