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Plant Sci：湖南農大丨氮素利用效率與鎘耐受性的平衡
期刊：plant science
主題：氮素利用效率與鎘耐受性的平衡
標題：Balance between nitrogen use efficiency and cadmium tolerance in Brassica napus and Arabidopsis thaliana
影響因子：3.785
檢測指標： H+、Cd2+、NO3-流速
檢測部位：根部液泡
H+、Cd2+、NO3-流實驗處理方法：
4周齡擬南芥，20 μM CdCl2處理3天
21日齡油菜，100 μM CdCl2處理7天
H+、Cd2+、NO3-流實驗測試液成份：
文獻無
推薦測試液成份：
擬南芥根部液泡：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：湖南農業大學張振華、廖瓊
英文摘要
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（谷歌機翻）
NO3-和Cd2+跨膜轉運到植物細胞液泡中依賴于其液泡膜質子泵，V-ATP酶和V-PPase的能量。如果這些泵的活性降低，則導致較少的NO3-和Cd2+被輸送到液泡中，這有助于提高植物的氮利用效率（NUE）和降低Cd2+耐受性。
調節NUE和Cd2+耐受性之間平衡的生理機制尚不清楚。在我們的研究中，使用具有差異NUE，香優15和814的兩種甘藍型油菜基因型和擬南芥的Atclca-2突變體和AtCAX4過表達系（AtCAX4-OE）來研究Cd2+應激反應。
我們發現甘藍型油菜基因型具有較高的NUE，對Cd2+脅迫更敏感。具有較高Cd2+液泡隔離能力（VSC）的AtCAX4-OE突變體限制NO3-隔離到根空泡中并促進NUE。具有降低的NO3-VSC的Atclca-2突變體增強了Cd2+隔離到根空泡中并且賦予比WT更大的Cd2+耐受性。這可能是由于V-ATP酶和V-PPase提供的能量在液泡中Cd2+和NO3-之間的競爭。通過抑制CLCa轉運蛋白的活性和增加CAX4轉運蛋白的活性來調節Cd2+和NO3-液泡積累之間的平衡將同時增強甘藍型油菜的NUE和Cd2+耐受性，這對于改善其Cd2+植物修復潛力是必需的。
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+ ?uxes and (D) Cd2+ ?uxes during the ?rst 160 s of measurements within the root vacuoles.