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

主题：氮素利用效率与镉耐受性的平衡

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

影响因子：3.785

检测指标： H+、Cd2+、NO3-流速

检测部位：根部液泡

H+、Cd2+、NO3-流实验处理方法：

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

H+、Cd2+、NO3-流实验测试液成份：

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推荐测试液成份：

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

作者：湖南农业大学张振华、廖琼

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.

中文摘要（谷歌机翻）

NO3-和Cd2+跨膜转运到植物细胞液泡中依赖于其液泡膜质子泵，V-ATP酶和V-PPase的能量。如果这些泵的活性降低，则导致较少的NO3-和Cd2+被输送到液泡中，这有助于提高植物的氮利用效率（NUE）和降低Cd2+耐受性。

调节NUE和Cd2+耐受性之间平衡的生理机制尚不清楚。在我们的研究中，使用具有差异NUE，香优15和814的两种甘蓝型油菜基因型和拟南芥的Atclca-2突变体和AtCAX4过表达系（AtCAX4-OE）来研究Cd2+应激反应。

我们发现甘蓝型油菜基因型具有较高的NUE，对Cd2+胁迫更敏感。具有较高Cd2+液泡隔离能力（VSC）的AtCAX4-OE突变体限制NO3-隔离到根空泡中并促进NUE。具有降低的NO3-VSC的Atclca-2突变体增强了Cd2+隔离到根空泡中并且赋予比WT更大的Cd2+耐受性。这可能是由于V-ATP酶和V-PPase提供的能量在液泡中Cd2+和NO3-之间的竞争。通过抑制CLCa转运蛋白的活性和增加CAX4转运蛋白的活性来调节Cd2+和NO3-液泡积累之间的平衡将同时增强甘蓝型油菜的NUE和Cd2+耐受性，这对于改善其Cd2+植物修复潜力是必需的。

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.