Physiological Mechanisms Of Arabidopsis Thaliana BGLU10 And BGLU18 Genes Regulating Cadmium Resistance

China's arable land contaminated by heavy metals has reached ten million hectares.Cadmium not only accumulates in certain organs of the human body,but also has toxic effects on plant growth and development..Abscisic acid?ABA?as a plant hormone not only plays an important regulatory role in plant growth and development,but also ABA is an important stress hormone.However,how it regulates the physiological and molecular mechanisms of plant tolerance to cadmium remains unclear.Arabidopsis wild type Col-0and mutants bglu10?bglu18 and B.napus?814?used as materials in this research,under hydroponic conditions,we studied the influence of 20?M CdCl₂ stress on Arabidopsis and10?M CdCl₂ stress on B.napus,aimed at exploring the regulatory mechanism of cadmium resistance in Arabidopsis wild-type and mutant plants and B.napus seedlings at the physiological and molecular level.The main results are as follows:1.BGLU10 and BGLU18 regulate the distribution of ABA sub-cells?vacuole-cytoplasm?in plants under cadmium stress:By measuring the ABA concentration in the vacuoles and cytoplasm of root cells,we found that the ABA concentration in the vacuoles of Arabidopsis wild-type Col-0 root cells accounted for 77.0%of the protoplast ABA concentration,while in the mutants bglu10 and bglu18 root cells,the ABA concentration in the vacuole accounted for 91.9%and 88.5%of the protoplast ABA concentration,respectively.The distribution of ABA in the wild-type cytoplasm was significantly higher than that of the mutants bglu10 and bglu18.2.BGLU10 and BGLU18 regulate the synergistic distribution of NO₃^-and Cd²⁺under cadmium stress to improve the tolerance of plants to cadmium:Since there are differences in the ABA concentration in the cytoplasm of wild-type and mutants root cells,compared to mutants,in Col-0,NRT1.5 down-regulates its expression in response to ABA,while NRT1.8does not respond to ABA.The signal causes more NO₃^-to be distributed in the root.At the same time,in the Col-0 root cells,the enzymatic activity of the tonoplast proton pump V-ATPase and V-PPase was significantly higher than that of the mutants,more Cd²⁺and NO₃^-were stored in the root vacuole,resulting in less Cd²⁺and NO₃^-are distributed in the cytoplasm,which reduces the transport of Cd²⁺and NO₃^-to the shoots,enhances the resistance of Col-0 but reduces the NUE?nitrogen use efficiency?.3.The addition of exogenous ABA enhanced the resistance of B.napus to cadmium and increased NUE:In B.napus,BnNRT1.5 down-regulated its expression in response to exogenous ABA signal,while BnNRT1.8 did not respond to ABA signal,resulting in more NO₃^-is distributed in the root.Not only the addition of exogenous ABA inhibited the absorption of cadmium and enhanced the anti-cadmium ability of B.napus,but also exogenous ABA enhanced the activity of NR in the roots and the activity of GS in the shoot,and promoted the transport of NH₄⁺to the shoot,thereby improving the NUE of B.napus.