Zn stress facilitates nitrate transporter 1.1-mediated nitrate uptake aggravating Zn accumulation in Arabidopsis plants

• Published in: Ecotoxicology and environmental safety 2020-03, Vol.190, p.110104, Article 110104
• Main Authors: Pan, Wei, You, Yue, Weng, Yi-Neng, Shentu, Jia-Li, Lu, Qi, Xu, Qian-Ru, Liu, Hui-Jun, Du, Shao-Ting
• Format: Article
• Language: English
• Subjects: Anion Transport Proteins - metabolism; Arabidopsis; Arabidopsis - drug effects; Arabidopsis - metabolism; Arabidopsis Proteins - metabolism; Biological Transport; Hydroponic; Ion Transport; Nitrate transporter; Nitrates; NRT1.1; Plant Proteins - metabolism; Plant Roots - metabolism; Zinc - metabolism; Zinc Compounds; Zn stress
• ISSN: 0147-6513; 1090-2414
• DOI: 10.1016/j.ecoenv.2019.110104

Describing the mechanisms of zinc (Zn) accumulation in plants is essential to counteract the effects of excessive Zn uptake in crops grown in contaminated soils. Increasing evidence suggests that there is a positive correlation between nitrate supply and Zn accumulation in plants. However, the role of the primary nitrate transporter NRT1.1 in Zn accumulation in plants remains unknown. In this study, a Zn stress-induced increase in nitrate uptake and an increase in NRT1.1 protein levels in wild-type (Col-0) Arabidopsis plants were measured using microelectrode ion flux and green fluorescent protein (GFP)/β-glucuronidase (GUS) staining, respectively. Both agar and hydroponic cultures showed that mutants lacking the NRT1.1 function in nrt1.1 and chl1-5 (chlorate resistant 1) exhibited lower Zn levels in the roots and shoots of Zn-stressed plants than the wild-type. A lack of NRT1.1 activity also alleviated Zn-induced photosynthetic damage and growth inhibition in plants. Further, we used a rotation system with synchronous or asynchronous uptakes of nitrate and Zn to demonstrate differences in Zn levels between the Col-0 and nrt1.1/chl1-5 mutants. Significantly lower difference in Zn levels were noted in the nitrate/Zn asynchronous treatment than in the nitrate/Zn synchronous treatment. From these results, it can be concluded that NRT1.1 modulates Zn accumulation in plants via a nitrate-dependent pathway. [Display omitted] •Zn stress triggered NRT1.1-mediated nitrate uptake.•Stress phenotypes of NRT1.1-deficient mutants supplemented with Zn were less evident.•Inhibition of NRT1.1 activity could reduce Zn levels in plants.•NRT1.1-regulated Zn accumulation in stressed-plants is nitrate-dependent.