PEG模拟干旱胁迫对不同抗逆性棉花的生理特性的影响

摘要

为了筛选培育棉花抗旱性的有用指标,利用聚乙二醇(PEG6000)模拟干旱,对不同类型棉花苗期干旱处理响应进行了评价.基质育苗后,采用5种不同浓度聚乙二醇胁迫棉花幼苗,7d后测定叶片的叶绿素、可溶性糖、可溶性蛋白、游离脯氨酸和丙二醛(MDA)含量的变化,比较过氧化物酶(POD)、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性的差异,结果表明:棉花苗期在不同浓度PEG胁迫下,叶绿素含量在5％的PEG胁迫下,表现含量略升高,高于10％ PEG浓度胁迫,叶绿素含量呈现下降的趋势;可溶性糖在10％ ～ 25％的PEG胁迫下表现高的含量;可溶性蛋白在5％PEG胁迫时,其含量开始增加并高于对照;游离脯氨酸含量表现为随着胁迫浓度的加大而升高,抗旱、抗盐品种增加的量高于敏感材料;丙二醛含量亦表现为随着胁迫浓度的加大而升高,在5％～15％的范围内,抗旱抗盐品种升高幅度低于敏感材料,在20％,25％的高浓度胁迫下,三种材料的差别很小;三种抗氧保护酶活性在不同材料不同胁迫浓度中表现出差异,POD酶活性在5％PEG干旱胁迫时即表现出上升趋势,在10％、15％胁迫浓度时达到最高值;SOD酶活性在5％的胁迫下高于对照,随着10％、15％、20％ PEG浓度逐渐增高,SOD酶活性均表现稳定的高活性;CAT酶活性在5％、10％ PEG胁迫时呈现增高趋势,在15％以上的PEG胁迫时活性迅速下降.由此认为,叶绿素、可溶性蛋白、脯氨酸和丙二醛含量可能是干旱胁迫下的植株被动响应的指标,可溶性糖合成可能是一种重要渗透调节方式;在不同干旱级别中不同抗氧保护酶在起主导作用,SOD酶可能是较好的抗旱性选择指标.%In order to find useful indexes of the drought resistance cotton,treatment response of different cotton types seedlings was evaluated by using PEG6000 simulated drought.First,using matrix seedlings,and then the cotton seedlings were stressed by five different concentration of PEG.After the stress lasted for seven days,the content changes of chlorophyll,soluble sugar,soluble protein,proline and malondialdehyde of seedling leaves were measured,and the differences of peroxidase,superoxide dismutase and catalase activity were compared.The results showed that the cotton seedling presented different physiological characteristics under the stress of different concentration PEG stress,Chlorophyll content increased slightly under 5 ％ PEG stress than the control,and chlorophyll content was lower than control in the 10％ PEG stress;soluble sugar content showed higher levels under 10％ ～ 25％ PEG stress;Soluble protein content increased more than control under 5 ％ PEG stress;Proline content in leaves increased with the increase of stress concentration,But proline content of drought resistant and salt resistant varieties were higher than sensitive materials;malondialdehyde content in leaves had similar trends as proline,but in the range of 5％ ～ 15％,the drought resistant and salt resistant varieties were lower than the sensitive materials,under 20％,25％ PEG stress,the difference of three kinds of material was very small.Three kinds of antioxidant protection enzymes showed different change patterns of activity under different material treatments.The enzyme activity of peroxidase increased from 5 ％ PEG stress,and the highest enzyme activity of peroxidase were displayed in 10％,15％ stress concentration.The enzyme activity of SOD in 5％ PEG stress was higher than that of the control,and along with the increased PEG stress(10％,15％,20％),SOD enzyme activities were stable and keeping higher levels.The enzyme activity of CAT increased in low concentration PEG stress (5％,10％),and it decreased rapidly in more than 15％ PEG stress.In conclusion,chlorophyll content,soluble protein,proline and malondialdehyde may be indexes of passive response of plants under drought stress.The soluble sugar is a kind of important osmotic regulation substance.In different levels of drought,different antioxidant protection enzymes play leading role,SOD enzyme may be a better drought resistance selection index.