芹菜对镉、铅胁迫的生理响应及抗氧化酶基因表达特性分析

为探讨芹菜在重金属镉、铅胁迫下的生理变化规律和抗氧化酶基因的表达特性,采用营养液培试验,研究镉(Cd)、铅(Pb)单一及复合胁迫对芹菜体内Cd/Pb富集、叶绿素、丙二醛(MDA)、谷胱甘肽(GSH)含量及抗氧化酶(SOD、POD)活性的影响,并用RT-q PCR技术检测了根尖细胞内抗氧化酶基因(Cat、Gpx、Mn-sod及Apx)的表达特性。结果表明,Cd~(2+)、Pb~(2+)单一及复合胁迫下芹菜茎叶中Cd~(2+)、Pb~(2+)含量均随胁迫浓度增大而逐渐增大,说明芹菜对Cd~(2+)、Pb~(2+)的吸收互为协同作用;6~8 mg·L-1Cd~(2+)和60~80 mg·L-1Pb~(2+)单一及复合处理对芹菜整个生长期内叶绿素、MDA、GSH含量及SOD、POD活性的影响均达到极显著水平(P0.01);低浓度下单一及复合胁迫对叶绿素合成有促进效应,高浓度、长时间胁迫时,叶绿素含量显著降低;单一及复合胁迫对MDA、GSH含量及SOD、POD活性的影响均为Cd~(2+)-Pb~(2+)交互Cd~(2+)Pb~(2+),但单一Cd~(2+)浓度≥4 mg·L-1时,叶绿素含量大于Cd~(2+)-Pb~(2+)交互及单一Pb胁迫;Cd~(2+)、Pb~(2+)对芹菜叶POD和SOD活性的影响相似,均表现为"低促高抑";MDA、GSH含量随重金属浓度的升高而逐渐增加;单一及复合处理下Cat、Gpx、Mn-sod及Apx表达模式基本一致,其表达量的降低幅度为Cd~(2+)-Pb~(2+)交互Cd~(2+)Pb~(2+)。综上,Cd~(2+)、Pb~(2+)胁迫对芹菜的生理和抗氧化系统均造成了一定的损伤,二者具有协同性,这为江西省鄱阳湖区芹菜的安全生产提供了理论依据。

Physiological Responses to Cd,Pb Pollution and Expression Analysis of Antioxidative Genes in Celery

To explore the physiological changes and expression analysis of antioxidative genes in celery (Apium graveolens) under Cd2+ stress and Pb2+ stress,a hydroponic experiment was conducted to investigate the effects of cadmium (Cd2 +) and lead (Pb2+) single and combined stresses of cadmium (Cd2 +) and lead (Pb2 +) on contents of Cd2+ or Pb2+,chlorophyll (Chl),malondialdehyde (MDA),glutathione (GSH),and antioxidant enzyme activities (SOD and POD),and were tested the expression of antioxidative genes with qRT-PCR in celery.The results showed that the concentration of Cd2+ or Pb2+ was promoted in single Cd2+/Pb2+ and Cd2+-Pb2+ combined pollution.Compared with CK,the influences of Cd2+,Pb2+ single andcombined stress on contents of Chl,GSH,MDA and activities of SOD and POD in the leaves were very significant difference (P ＜ 0.01) during the whole growth cycle of celery.Content of Chl was increased under the low concentrations of Cd2+,Pb2+ and Cd2+-Pb2+ combined stress,but decreased under high concentrations and long time.The effects of Cd2+,Pb2+ on MDA,GSH,SOD and POD followed the order of Cd2+-Pb2+ combined ＞ Cd2+ ＞ Pb2+,but after treated with the concentration of Cd2+ ≥ 4 mg· L-1,the destructive effects on Chl showed Cd2 + ＞ Cd2 +-Pb2 + ＞ Pb2 +.The effects of Cd2 +,Pb2 + on activities of POD and SOD in celery leaf were similar.Both existed hormesis effect.Contents of MDA and GSH were promoted gradually with heavy metal concentration increasing.Expression patterns of Cat,Gpx,Mn-sod and Apx had the similar results under Cd2+,Pb2+ and Cd2 +-Pb2 +,and such reduction was Cd2 +-Pb2 + combined ＞ Cd2 + ＞ Pb2 +.In a conclusion,this study demonstrated that physiological system and antioxidant system of celery were damaged under Cd2+ and Pb2+ stress.