ABA对盐胁迫下侧柏活性氧代谢及其相关基因表达的研究

摘要

The reactive oxygen metabolism under different salt levels and the alleviative effects of exogenous abscisic acid (ABA)on plants against salt stress were assessed in Platycladus orientalis seedlings treated with different concentrations of NaCl and ABA.P.orientalis seedlings were cultured by 1/4 Hoagland so-lution with different levels of NaCl (100,200,300 and 400 mmol·L-1 ),and 1/4 Hoagland solution was used as control.Furthermore,seedlings exposed to 300μmol·L-1 NaCl were treated with different con-centrations(0,0.5,1,10,100 and 200μmol·L-1 )of ABA,and physiological indexes and expression levels of genes related to reactive oxygen metabolism were studied.The results showed that:(1)With the increase of NaCl level,the contents of hydrogen peroxide (H2 O2 ),malondialdehyde (MDA),glutathione (GSH)and proline and activities of antioxidant enzymes (SOD,POD,CAT)in P.orientalis leaves in-creased,while soluble protein content decreased.(2)Salinity-treated plants exposed to ABA at 1 and 10μmol·L-1 for 48 h significantly enhanced the activities of SOD,POD and CAT,and increased the con-tents of GSH,proline and soluble protein,accompanied by decreased accumulation of H2 O2 and MDA.(3) NaCl stress caused the variation of the expression levels of genes related to reactive oxygen metabolism in P.orientalis,and the presence of 10 μmol · L-1 ABA maximally induced expression levels of Cu/Zn-SOD,CAT,GR,APX,MDAR and GST genes in 300mmol·L-1 NaCl-treated seedlings.These results suggested that exogenous ABA could promote antioxidant enzyme activities,increase osmotic adj ustment ability and GSH content,decrease the accumulation of MDA and H2 O2 in leaves of P.orientalis under salt stress,thereby effectively reduce the damage of reactive oxygen species to P.orientalis leaves and enhance its salt resistance.%以侧柏幼苗为试验材料,采用水培方式,研究不同浓度NaCl(0、100、200、300和400 mmol·L-1)以及ABA(0、0.5、1、10、100和200μmol·L-1)处理对盐胁迫下侧柏幼苗活性氧代谢的影响.结果显示:(1)随着NaCl处理浓度增加,侧柏幼苗叶片过氧化氢(H2 O2)、丙二醛(MDA)、谷胱甘肽(GSH)和脯氨酸含量,以及抗氧化物酶(SOD、POD和CAT)活性呈上升趋势,而可溶性蛋白含量降低.(2)于300 mmol·L-1 NaCl胁迫处理48 h后进行ABA(1和10μmol·L-1)处理,分析发现侧柏幼苗叶片的SOD、POD和CAT活性提高,GSH、脯氨酸和可溶性蛋白含量增加,H2 O2和MDA的积累减少.(3)NaCl胁迫后,侧柏幼苗叶片活性氧代谢相关基因(Cu/Zn-SOD、CAT、GR、APX、MDAR和GST)的表达水平随ABA浓度增加呈先升后降的趋势,并于10μmol·L-1 ABA处理48 h时达到峰值.研究表明,适宜浓度ABA通过促进盐胁迫下侧柏幼苗叶片的抗氧化物酶活性,提高渗透调节能力,增加GSH含量,降低H2 O2和MDA积累,从而有效降低活性氧对侧柏叶片的伤害,保护细胞膜结构的完整,增强其抗盐性.