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Plant Sci:湖南农大丨氮素利用效率与镉耐受性的平衡-附NMT实验体系

期刊:plant science


标题:Balance between nitrogen use efficiency and cadmium tolerance in Brassica napus and Arabidopsis thaliana


检测指标: H+、Cd2+、NO3-流速



4周龄拟南芥,20 μM CdCl2处理3天
21日龄油菜,100 μM CdCl2处理7天




拟南芥根部液泡:0.002mM CdCl2,0.1 mM KNO3 , 600 mM mannitol, 0.05mM MES, pH 7.2

油菜根部液泡:0.01mM CdCl2,0.1 mM KNO3 , 600 mM mannitol, 0.05mM MES, pH 7.2





The transmembrane transport of NO3− andCd2+ into plant cell vacuoles relies on the energy from their tonoplast protonpumps, V-ATPase and V-PPase. If the activity of these pumps is reduced, itresults in less NO3− and Cd2+ being transported into the vacuoles, whichcontributes to better nitrogen use efficiency (NUE) and lower Cd2+ tolerance inplants.

The physiological mechanisms that regulatethe balance between NUE and Cd2+ tolerance remain unknown. In our study, twoBrassica napus genotypes with differential NUEs, xiangyou 15 and 814, andAtclca-2 mutant and AtCAX4 over-expression line (AtCAX4-OE) of Arabidopsisthaliana, were used to investigate Cd2+ stress responses.

We found that the Brassica napus genotype,with higher NUE, was more sensitive to Cd2+ stress. The AtCAX4-OE mutant, withhigher Cd2+ vacuolar sequestration capacity (VSC), limited NO3− sequestrationinto root vacuoles and promoted NUE. Atclca-2 mutants, with decreased NO3− VSC,enhanced Cd2+ sequestration into root vacuoles and conferred greater Cd2+tolerance than the WT. This may be due to the competition between Cd2+ andNO3−in the vacuoles for the energy provided by V-ATPase and V-PPase. Regulating thebalance between Cd2+ and NO3− vacuolar accumulation by inhibiting the activityof CLCa transporter and increasing the activity of CAX4 transporter willsimultaneously enhance both the NUE and Cd2+ tolerance of Brassica napus,essential for improving its Cd2+ phytoremediation potential.






Fig. 2. The Arabidopsis thaliana vha-a2, vha-a3, and avp1 mutants were more sensitive to Cd2+ stress than the wild-type Col-0. (A) The phenotype and (B) the chlorophyll loss, in relation to the controls, of Col-0 and the vha-a2, vha-a3, and avp1 mutants grown for 4 weeks and then exposed to 20 μM CdCl2 for 3 days. Mean rates of (C) H+ fluxes and (D) Cd2+ fluxes during the first 160 s of measurements within the root vacuoles.