摘要：

以镉敏感小麦川麦28(CM28)为研究对象,探究在不同浓度镉胁迫下喷施外源甘氨酸对其生理生化过程的影响。测定了不同处理下CM28的株高和根长、镉的地上部转运系数与富集系数、叶绿素含量和丙二醛(MDA)含量以及超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)的活性,并利用qRT-PCR技术分析不同处理下根部和叶片中PEPC基因的表达水平。结果表明,30 μmol/L镉胁迫下,喷施外源甘氨酸会导致CM28地上部干质量与鲜质量下降,总叶绿素含量下降,MDA含量上升,表明植物受活性氧的影响程度增强。50 μmol/L镉胁迫下,甘氨酸能有效缓解镉胁迫对CM28产生的负面影响,使其总叶绿素含量上升,地上部干质量与鲜质量上升,MDA含量下降,表明植物受活性氧影响的程度降低。CM28的抗氧化酶活性随着镉浓度的升高而整体升高,喷施外源甘氨酸能在整体上提升抗氧化酶的活性,缓解镉胁迫导致的活性氧影响。根部PEPC基因的表达随着镉浓度的上升而整体上升,表明PEPC在植物根部抗逆性胁迫的过程中起着重要作用,外源甘氨酸的喷施在整体上也能有效缓解CM28受到的镉胁迫,引起PEPC基因的表达降低。综上所述,镉胁迫对CM28的生理生化过程具有不利影响,喷施外源甘氨酸能在一定程度上缓解镉对CM28的影响。

关键词: 小麦, 镉胁迫, 活性氧, 抗氧化酶促防御系统, PEPC基因

Abstract:

Cd-sensitive wheat CM28 was used as the research object to investigate the effects of spraying exogenous glycine on its physiological and biochemical processes under different concentrations of cadmium stress.The plant height and root length,above-ground transport coefficient and enrichment coefficient of cadmium,chlorophyll content and malondialdehyde(MDA)content,and the enzyme activities of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT)of CM28 under different treatments were determined.The expression levels of PEPC genes in roots and leaves under different treatments were analyzed by qRT-PCR.The results showed that under 30 μmol/L Cd stress,the spraying of exogenous glycine led to a decrease in the above-ground dry and fresh weights,a decrease in the total-chlorophyll content,and an increase in the MDA content of CM28,indicating that plants were affected by more reactive oxygen species.Under 50 μmol/L cadmium stress,glycine could effectively alleviate the negative effects of cadmium on CM28,resulting in an increase in the total-chlorophyll content,an increase in the above-ground dry and fresh weights,and a decrease in MDA content,suggesting that the plant was affected by reactive oxygen species to a greater extent.The antioxidant enzyme activity of CM28 increased with the increase of cadmium concentration,and the spraying of exogenous glycine could enhance the activity of antioxidant enzymes and alleviate the effect of cadmium on the whole.The expression of PEPC genes in roots increased overall with the rise of cadmium concentration,indicating that PEPC played an important role in the process of plant root resistance to stress,and the spraying of exogenous glycine can also effectively alleviate the cadmium stress on CM28 and reduce the expression of PEPC genes on the whole.In summary,cadmium stress negatively affects the physiological and biochemical processes of CM28,and the spraying exogenous glycine can alleviate the effects.

Key words: Triticum aestivum L., Cadmium stress, Reactive oxygen species, Antioxidant enzyme system, PEPC gene