荒漠植物沙芥苗期对不同浓度NaCl的适应机制  

Adaptive responses of eremophyte Pugionium cornutum seedlings to different concentrations of NaCl

作　　者：岳利军[1] 袁坤[1] 李海伟[1] 康建军[2] 王锁民[1] 

机构地区：[1]兰州大学草地农业科技学院草地农业生态系统国家重点实验室,甘肃兰州730020 [2]中国科学院寒区旱区环境与工程研究所内陆河流域生态水文重点实验室,甘肃兰州730000

出　　处：《草业学报》2016年第1期144-152,共9页Acta Prataculturae Sinica

基　　金：国家自然科学基金项目(31101750;31360086);兰州大学中央高校基本科研业务费专项资金(lzujbky-2013-200)资助

摘　　要：本文研究了5周龄沙芥幼苗对不同浓度NaCl的适应机制。结果表明,沙芥苗期对不同浓度的NaCl具有不同的适应机制。与对照相比,在5mmol/L的低浓度NaCl下,沙芥叶的干重和含水量分别显著增加了25%和35%(P<0.05),沙芥正是通过这种植株的快速生长和含水量的增加将进入体内过多的Na+稀释至毒害水平以下,以适应外界低浓度的NaCl。在50mmol/L的中等浓度NaCl下,沙芥限制了K+、增强了Na+从根向叶的选择性运输,使叶中的Na+含量显著增加了8倍(P<0.05),沙芥最可能是将叶中积累的大量Na+区域化至液泡中来适应外界中等浓度的NaCl,该机制避免了Na+对叶细胞的伤害,使叶的渗透势显著降低了75%(P<0.05),让植株有效地抵御了盐分产生的渗透胁迫,维持了沙芥的正常生长。沙芥主要通过限制Na+、增强K+的选择性吸收和从根向叶的选择性运输来适应外界高浓度的NaCl。在200 mmol/L的高浓度NaCl下,该机制使沙芥叶中积累的K+较50mmol/L的NaCl下显著增加了55%(P<0.05),使K+对渗透调节的贡献率也相应地从10.28%提高到了12.51%,K+一般积累于细胞质中,因此该机制有利于叶细胞质保持较低的Na+/K+、减缓Na+对叶的伤害,也有利于细胞质平衡来自胞内液泡和胞外高浓度NaCl产生的渗透压、减少叶的渗透伤害。尽管如此,在200mmol/L的NaCl下,沙芥幼苗生长了7d便使其叶的干重显著降低了51%(P<0.05),表明沙芥苗期的耐盐性有限。To investigate the adaptive mechanisms of Pugionium cornutum seedlings at different NaCl concentrations,5-week-old seedlings were treated with a series of external NaCl concentrations(5,25,50,100and200mmol/L).The seedlings exhibited different adaptive mechanisms at different NaCl concentrations.At low salt concentrations(5 mmol/L NaCl),leaf dry weight and water content significantly increased by 25% and35%respectively compared to the control(P<0.05).The adaptation of P.cornutumto low salt concentrations was mainly due to the rapid growth and increased water content of the plant,which could dilute the excessively absorbed Na+to below toxic levels.At moderate salt concentrations(50mmol/L NaCl),a strong controlled K+and promoted Na+transportation from root to leaf was observed,and leaf Na+concentration was 8-fold higher than that in the control plants(P<0.05).This adaptation might be explained by the plant's ability to compartmentalize excess Na+into the vacuole in leaf cells,which could protect leaves from Na+toxicity and produce a 75% decrease in leaf osmotic potential(P<0.05).Therefore,the ability of plants to resist the osmotic stress induced by NaCl was enhanced and normal plant growth could be maintained.The adaptation of P.cornutumto high concentrations of salt(200mmol/L NaCl)was caused by a strong controlled Na+and promoted K+transportation from the outside into the plant and then from root to leaf.This resulted in a 55%increase in leaf K+concentration under the high-concentration treatment compared to the 50mmol/L treatment(P<0.05),with a corresponding increase from 10.28%to 12.51%in the contribution of K+to osmotic potential.This mechanism could help to maintain a low Na+/K+within the cytoplasm,reduce Na+toxicity to cells,balance the osmotic pressure from vacuole and apoplast to cytoplasm,and reduce osmotic stress on cells due to the primary location of K+mainly in the cytoplasm.However,leaf dry weight significantly decreased by 51%at 200mmol/L NaCl grown for 7dcompared to control(P<0.05),indicating that P

关 键 词：沙芥 NACL 适应机制 

分 类 号：Q945[生物学—植物学]