Chen Yi, Sun Sheng-Kai, Tang Zhong, Liu Guidong, Moore Katie L, Maathuis Frans J M, Miller Antony J, McGrath Steve P, Zhao Fang-Jie
Department of Sustainable Soils and Grassland Systems, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK.
Department of Metabolic Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
J Exp Bot. 2017 May 17;68(11):3007-3016. doi: 10.1093/jxb/erx165.
Previous studies have shown that the Nodulin 26-like intrinsic membrane protein (NIP) Lsi1 (OsNIP2;1) is involved in arsenite [As(III)] uptake in rice (Oryza sativa). However, the role of other rice NIPs in As(III) accumulation in planta remains unknown. In the present study, we investigated the role OsNIP3;2 in As(III) uptake in rice. When expressed in Xenopus laevis oocytes, OsNIP3;2 showed a high transport activity for As(III). Quantitative real-time RT-PCR showed that the expression of OsNIP3;2 was suppressed by 5 µM As(III), but enhanced by 20 and 100 µM As(III). Transgenic rice plants expressing OsNIP3;2pro-GUS showed that the gene was predominantly expressed in the lateral roots and the stele region of the primary roots. Transient expression of OsNIP3;2:GFP fusion protein in rice protoplasts showed that the protein was localized in the plasma membrane. Knockout of OsNIP3;2 significantly decreased As concentration in the roots, but had little effect on shoot As concentration. Synchrotron microfocus X-ray fluorescence showed decreased As accumulation in the stele of the lateral roots in the mutants compared with wild-type. Our results indicate that OsNIP3;2 is involved in As(III) uptake by lateral roots, but its contribution to As accumulation in the shoots is limited.
先前的研究表明，结节蛋白26样内在膜蛋白（NIP）Lsi1（OsNIP2;1）参与水稻（Oryza sativa）对亚砷酸盐[As（III）]的吸收。然而，其他水稻NIPs在植物体内As（III）积累中的作用仍不清楚。在本研究中，我们调查了OsNIP3;2在水稻As（III）吸收中的作用。当在非洲爪蟾卵母细胞中表达时，OsNIP3;2对As（III）表现出高转运活性。定量实时RT-PCR表明，5 μM As（III）抑制OsNIP3;2的表达，但20和100 μM As（III）增强其表达。表达OsNIP3;2pro-GUS的转基因水稻植株表明，该基因主要在侧根和初生根的中柱区域表达。OsNIP3;2:GFP融合蛋白在水稻原生质体中的瞬时表达表明，该蛋白定位于质膜。敲除OsNIP3;2显著降低了根中的As浓度，但对地上部As浓度影响不大。同步辐射微聚焦X射线荧光显示，与野生型相比，突变体侧根中柱的As积累减少。我们的结果表明，OsNIP3;2参与侧根对As（III）的吸收，但其对地上部As积累的贡献有限。
