Soil contamination with toxic heavy metals[such as cadmium(Cd)]is becoming a serious global problem due to rapid development of social economy.Iron(Fe),being an important element,has been found effective in enhancing ...Soil contamination with toxic heavy metals[such as cadmium(Cd)]is becoming a serious global problem due to rapid development of social economy.Iron(Fe),being an important element,has been found effective in enhancing plant tolerance against biotic and abiotic stresses.The present study investigated the extent to which different levels of Ferrous sulphate(FeSO_(4))modulated the Cd tolerance of rice(Oryza sativa L.),when maintained in artificially Cd spiked regimes.A pot experiment was conducted under controlled conditions for 146 days,by using natural soil,mixed with different levels of CdCl_(2)[0(no Cd),0.5 and 1 mg/kg]together with the exogenous application of FeSO_(4) at[0(no Fe),1.5 and 3 mg/kg]levels to monitor different growth,gaseous exchange characteristics,oxidative stress,antioxidative responses,minerals accumulation,organic acid exudation patterns of O.sativa.Our results depicted that addition of Cd to the soil significantly(P<0.05)decreased plant growth and biomass,gaseous exchange parameters,mineral uptake by the plants,sugars(soluble,reducing,and non-reducing sugar)and altered the ultrastructure of chloroplasts,plastoglobuli,mitochondria,and many other cellular organelles in Cd-stressed O.sativa compared to those plants which were grown without the addition of Cd in the soil.However,Cd toxicity boosted the production of reactive oxygen species(ROS)by increasing the contents of malondialdehyde(MDA),which is the indication of oxidative stress in O.sativa and was also manifested by hydrogen peroxide(H_(2)O_(2))contents and electrolyte leakage to the membrane bounded organelles.Although,activities of various antioxidative enzymes like superoxidase dismutase(SOD),peroxidase(POD),catalase(CAT)and ascorbate peroxidase(APX)and non-enzymatic antioxidants like phenolics,flavonoid,ascorbic acid,anthocyanin and proline contents increased up to a Cd level of 0.5 mg/kg in the soil but were significantly diminished at the highest Cd level of 1 mg/kg in the soil compared to those plants which were grown without the addition of Cd in the soil.The negative impacts of Cd injury were reduced by the application of FeSO_(4) which increased plant growth and biomass,improved photosynthetic apparatus,antioxidant enzymes,minerals uptake together with diminished exudation of organic acids as well as oxidative stress indicators in roots and shoots of O.sativa by decreasing Cd retention in different plant parts.These results shed light on the effectiveness of FeSO_(4) in improving the growth and upregulation of antioxidant enzyme activities of O.sativa in response to Cd stress.However,further studies at field levels are required to explore the mechanisms of FeSO_(4)-mediated reduction of the toxicity of not only Cd,but possibly also other heavy metals in plants.展开更多
基金the National Key Research and Development Program of China(Grant No.2017YFC0504704)the National Natural Science Foundation of China(51669034,41761068,51809224).
文摘Soil contamination with toxic heavy metals[such as cadmium(Cd)]is becoming a serious global problem due to rapid development of social economy.Iron(Fe),being an important element,has been found effective in enhancing plant tolerance against biotic and abiotic stresses.The present study investigated the extent to which different levels of Ferrous sulphate(FeSO_(4))modulated the Cd tolerance of rice(Oryza sativa L.),when maintained in artificially Cd spiked regimes.A pot experiment was conducted under controlled conditions for 146 days,by using natural soil,mixed with different levels of CdCl_(2)[0(no Cd),0.5 and 1 mg/kg]together with the exogenous application of FeSO_(4) at[0(no Fe),1.5 and 3 mg/kg]levels to monitor different growth,gaseous exchange characteristics,oxidative stress,antioxidative responses,minerals accumulation,organic acid exudation patterns of O.sativa.Our results depicted that addition of Cd to the soil significantly(P<0.05)decreased plant growth and biomass,gaseous exchange parameters,mineral uptake by the plants,sugars(soluble,reducing,and non-reducing sugar)and altered the ultrastructure of chloroplasts,plastoglobuli,mitochondria,and many other cellular organelles in Cd-stressed O.sativa compared to those plants which were grown without the addition of Cd in the soil.However,Cd toxicity boosted the production of reactive oxygen species(ROS)by increasing the contents of malondialdehyde(MDA),which is the indication of oxidative stress in O.sativa and was also manifested by hydrogen peroxide(H_(2)O_(2))contents and electrolyte leakage to the membrane bounded organelles.Although,activities of various antioxidative enzymes like superoxidase dismutase(SOD),peroxidase(POD),catalase(CAT)and ascorbate peroxidase(APX)and non-enzymatic antioxidants like phenolics,flavonoid,ascorbic acid,anthocyanin and proline contents increased up to a Cd level of 0.5 mg/kg in the soil but were significantly diminished at the highest Cd level of 1 mg/kg in the soil compared to those plants which were grown without the addition of Cd in the soil.The negative impacts of Cd injury were reduced by the application of FeSO_(4) which increased plant growth and biomass,improved photosynthetic apparatus,antioxidant enzymes,minerals uptake together with diminished exudation of organic acids as well as oxidative stress indicators in roots and shoots of O.sativa by decreasing Cd retention in different plant parts.These results shed light on the effectiveness of FeSO_(4) in improving the growth and upregulation of antioxidant enzyme activities of O.sativa in response to Cd stress.However,further studies at field levels are required to explore the mechanisms of FeSO_(4)-mediated reduction of the toxicity of not only Cd,but possibly also other heavy metals in plants.
