星星草响应盐碱胁迫的渗透调节和离子平衡机制

Mechanism of osmotic adjustment and ionic balance in Puccinellia tenuiflora in response to salt and alkali stresses

为探索天然抗碱牧草星星草抗盐碱的生理机制,根据东北地区盐碱化草原土壤所含的可溶性盐分的组成特点,模拟出0～240mmol/L的盐胁迫和碱胁迫条件,对苗龄8周的星星草(Puccinellia tenuiflora)幼苗进行了两种胁迫处理,分析了两种胁迫下植株的渗透调节和离子平衡机制.结果表明:在盐、碱胁迫下,脯氨酸是主要的有机渗透调节物质,而甜菜碱和胆碱的作用却非常有限.碱胁迫下星星草体内大量积累的有机酸不仅起到渗透调节作用,而且也是主要的负电荷来源,在体内离子平衡及pH调节中起重要作用.在两种胁迫下,Na+,K+,Cl-和有机酸的含量占到总溶质的80.7%和85.4%.碱胁迫下有机酸积累与Na+含量增加密切相关.碱胁迫造成植物体内Na+含量急剧的上升,导致细胞内离子平衡被破坏,这可能就是引起有机酸相应大量积累的主要原因.

The stresses triggered by the soluble salts and alkali salts of the salt alkaline grasslands of north-eastern China were simulated.Eight-week-old Puccinellia tenuiflora seedlings were treated with either of these salts to study changes of the salt resistant and alkali resistant mechanisms by plants.The treatments included salt concentrations ranging from 0 to 240 mmol/L.Mechanism of osmotic adjustment and ionic balance in P.tenuiflora in response to salt and alkali stresses were analyzed.Results show that proline is the main organic osmolyte while the contributions of betaine and sincaline to osmotic adjustment are insignificant under either salt or alkali stress.The main organic acid accumulated was not only an important organic osmotic regulator but also an important negative charge contributor,playing important roles in ionic balance and pH adjustment.The concentrations of Na＋,K＋,Cl-and of organic acid were 80.7% of all solutes under salt stress.The concentrations of Na＋,K＋,Cl-and of organic acid were 85.4% of all solutes under alkali stresses.Organic acid accumulation is closely related with Na＋ concentration increasing.The ionic balance was disrupted by the strong increase in Na＋ content under alkali stress.This perhaps explains why large amounts of the organic acids were accumulated.