Department of Biological Sciences, Birla Institute of Technology and Science Pilani, K. K. Birla Goa Campus, Goa, 403726, India.
Plant Stress Biology Laboratory, Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi, Uttar Pradesh, 221005, India.
Plant Physiol Biochem. 2024 May;210:108608. doi: 10.1016/j.plaphy.2024.108608. Epub 2024 Apr 9.
Tonoplast Intrinsic Proteins (TIPs) are vital in transporting water and solutes across vacuolar membrane. The role of TIPs in the arsenic stress response is largely undefined. Rice shows sensitivity to the arsenite [As[III]] stress and its accumulation at high concentrations in grains poses severe health hazards. In this study, functional characterization of OsTIP1;2 from Oryza sativa indica cultivar Pusa Basmati-1 (PB-1) was done under the As[III] stress. Overexpression of OsTIP1;2 in PB-1 rice conferred tolerance to As[III] treatment measured in terms of enhanced shoot growth, biomass, and shoot/root ratio of overexpression (OE) lines compared to the wild-type (WT) plants. Moreover, seed priming with the IRW100 yeast cells (deficient in vacuolar membrane As[III] transporter YCF1) expressing OsTIP1;2 further increased As[III] stress tolerance of both WT and OE plants. The dithizone assay showed that WT plants accumulated high arsenic in shoots, while OE lines accumulated more arsenic in roots than shoots thereby limiting the translocation of arsenic to shoot. The activity of enzymatic and non-enzymatic antioxidants also increased in the OE lines on exposure to As[III]. The tissue-specific localization showed OsTIP1;2 promoter activity in root and root hairs, indicating its possible root-specific function. After As[III] treatment in hydroponic medium, the arsenic translocation factor (TF) for WT was around 0.8, while that of OE lines was around 0.2. Moreover, the arsenic content in the grains of OE lines reduced significantly compared to WT plants.
液泡膜内在蛋白（TIPs）在水和溶质跨液泡膜运输中起着至关重要的作用。TIPs 在砷胁迫响应中的作用在很大程度上尚未确定。水稻对亚砷酸盐[As（III）]胁迫敏感，其在高浓度下在谷物中的积累对健康造成严重危害。在这项研究中，对来自印度香米品种 Pusa Basmati-1（PB-1）的 OsTIP1;2 进行了功能表征，在 As（III）胁迫下进行了研究。与野生型（WT）植物相比，在 PB-1 水稻中过表达 OsTIP1;2 可提高 shoot 生长、生物量和 shoot/root 比值，从而提高对 As（III）处理的耐受性。此外，用缺乏液泡膜 As（III）转运蛋白 YCF1 的 IRW100 酵母细胞（yeast cells）对 WT 和 OE 植物进行种子引发，进一步提高了它们对 As（III）胁迫的耐受性。二硫代二氮杂菲测定表明，WT 植物在 shoot 中积累了大量砷，而 OE 系在根中积累的砷多于 shoot，从而限制了砷向 shoot 的转运。暴露于 As（III）后，OE 系中的酶和非酶抗氧化剂活性也增加。组织特异性定位显示 OsTIP1;2 启动子在根和根毛中有活性，表明其可能具有根特异性功能。在水培介质中进行 As（III）处理后，WT 的砷转运因子（TF）约为 0.8，而 OE 系的 TF 约为 0.2。此外，OE 系的籽粒中砷含量与 WT 植物相比显著降低。
