盐胁迫下三种柳枝稷生理特性及同工酶研究

The study on Physiological Characteristics and Isoenzymes of Three Switchgrass (Panicum virgatum) under Salinity Stress

以柳枝稗低地型品种Alamo和高地型品种Caddo、Dacotah为材料,采用终浓度为250mmol/L的Na^+溶液进行处理,研究盐胁迫对三种柳枝稷生理特性的影响。结果表明:三种柳枝稷受到盐胁迫时,相对含水量(RWC)的变化程度为Caddo>Dacotah>Alamo,在胁迫5d时电导解质渗透率(EL)的变化为Caddo>Alamo>Dacotah。叶片和根系中丙二醛(MDA)含量随盐胁迫时间的延长呈先下降再上升的趋势,其中,品种Caddo的MDA含量比率(叶片/根系)最高,Dacotah次之,Alamo最小。品种Caddo叶脯氨酸含量变化较大,5d时达到最大值3.45μmol/g·FW。各处理天数下,品种Caddo叶片和根系的可溶性蛋白含量均为最高。品种Caddo叶片和根系APX活性均随胁迫时间增加呈上升趋势,处理10d时,叶片APX活性达7712.20U,与其他两个品种差异极显著(P<0.01),品种Dacotah叶片和根系CAT活性随胁迫时间增加均呈先上升再下降的趋势,在处理5d时分别达到最高峰值464.46U和111.63U,与其他两个品种差异极显著(P<0.01),在5d、10d盐胁迫处理下,叶片SOD活性均以Caddo品种最高。同时测定了胁迫10d时3个品种根系的抗氧化同工酶,其中APX产生3种同工酶,SOD产生4种同工酶,CAT产生1种同工酶。初步评价表明,3个品种耐盐性依次为:Alamo>Dacotah>Caddo。

In this experiment,lowland varieties(cv.Alamo)and highland varieties(cv.Caddo,cv.Dacotah)were used as test materials.The effects of salt stress on physiological characteristics of three switchgrass cultivar were studied by using Na^+solution with final concentration of 250 mmol/L.The results showed that:(1)Under salinity stress,the relative water content(RWC)and electrical conductivity(EL)of Caddo were the largest,which were 79.89%and 43.39%,respectively.The change degree of RWC was Caddo>Dacotah>Alamo,and the change of EL was Caddo>Alamo>Dacotach at 5 d.The content of malondialdehyde(MDA)in leaves and roots decreased first and then increased with the extension of salinity stress time.Among them,the ratio of MDA content(leaf/root)of Caddo was the highest,Dacotah was the second,and Alamo was the lowest.(2)Among Proline indicators,Proline content in Caddo leaves first increased and then decreased with the increase of stress days,and reached the highest peak of 3.45μmol/g·FW at 5 d.The soluble protein content of the leaves and roots of Caddo was the highest.While the content of Soluble protein in leaves and roots decreased at first,then it increased,as salt stress time prolonged.The maximum reached to 33.19 mg/g·FW at 10 d.(3)The APX activity of leaves and roots of Caddo increased with the increase of stress time.When treated for 10 days,the APX activity of leaves increased to 7712.20 U,which was significantly different from the other two cultivar(P<0.05).The catalase(CAT)activity of leaves and roots of Dacotah increased firstly and then decreased with the increase of stress time.The highest peaks were 464.46 U and 111.63 U,respectively,after treatment for 5 d,which was significantly different from the other two cultivar(P<0.01).The SOD activity of leaves was the highest in Caddo under 5 d and 10 d salt stress treatment.(4)Simultaneous determination of antioxidant isoenzymes in roots of three cultivars at 10 d,in which APX produced three interacting isoenzymes,and SOD showed four bright bands,producing four different isozymes.CAT presented 1 bright strip.After the comprehensive evaluation of salt tolerance of the leaves and roots of three switchgrass species in this experiment,it was concluded that the order of salt tolerance was:Alamo>Dacotah>Caddo.