College of Ecology and Environment, Chengdu University of Technology, Chengdu, 610059, China.
College of Agronomy, Sichuan Agricultural University, Chengdu, 611130, China.
BMC Plant Biol. 2023 Nov 11;23(1):556. doi: 10.1186/s12870-023-04540-0.
As one of the major food crops in the world, rice is vulnerable to cadmium (Cd) pollution. Understanding of the molecular mechanisms of Cd uptake, transport and detoxification in rice is essential for the breeding of low-Cd rice. However, the molecular mechanisms underlying the response of rice to Cd stress remains to be further clarified.
In this study, a novel Cd-responsive gene OsHARBI1-1 was identified in the rice genome and its expression pattern and function were characterized. Bioinformatics analysis showed that the promoter region of OsHARBI1-1 had multiple cis-acting elements in response to phytohormones and stress, and the expression of OsHARBI1-1 was induced by phytohormones. OsHARBI1-1 protein was targeted to the nucleus. qRT-PCR analysis results showed that the expression of OsHARBI1-1 in the roots was repressed while the expression in the shoots was increased under Cd stress. Heterologous expression of OsHARBI1-1 in yeast conferred tolerance to Cd and reduced Cd content in the cells. Meanwhile, the expression of OsHARBI1-1 in Arabidopsis thaliana (A. thaliana) enhanced the tolerance of A. thaliana to Cd stress. In addition, compared with the wild type plants, the POD activity of transgenic plants was increased, while the SOD and CAT activities were decreased. Interestingly, the accumulation of Cd in the roots of A. thaliana expressing OsHARBI1-1 was significantly increased, whereas the Cd accumulation in the shoots was slightly decreased. Compared to the WT plants, the expression of genes related to Cd absorption and chelation was upregulated in transgenic A. thaliana under Cd stress, while the expression of genes responsible for the translocation of Cd from the roots to the shoots was downregulated. Moreover, the expression of phytohormone-related genes was significantly influenced by the expression of OsHARBI1-1 with and without Cd treatment.
Findings of this study suggest that OsHARBI1-1 might play a role in the response of plants to Cd response by affecting antioxidant enzyme activities, Cd chelation, absorption and transport, and phytohormone homeostasis and signaling.
作为世界主要粮食作物之一，水稻易受到镉（Cd）污染。了解水稻对 Cd 吸收、转运和解毒的分子机制对于培育低 Cd 水稻至关重要。然而，水稻对 Cd 胁迫响应的分子机制仍有待进一步阐明。
本研究在水稻基因组中鉴定了一个新的 Cd 响应基因 OsHARBI1-1，并对其表达模式和功能进行了表征。生物信息学分析表明，OsHARBI1-1 启动子区域具有多种响应植物激素和胁迫的顺式作用元件，且 OsHARBI1-1 的表达受植物激素诱导。OsHARBI1-1 蛋白定位于细胞核。qRT-PCR 分析结果表明，Cd 胁迫下 OsHARBI1-1 在根中的表达受到抑制，而在地上部的表达增加。OsHARBI1-1 在酵母中的异源表达赋予酵母对 Cd 的耐受性并降低细胞内的 Cd 含量。同时，OsHARBI1-1 在拟南芥（Arabidopsis thaliana）中的表达增强了拟南芥对 Cd 胁迫的耐受性。此外，与野生型植物相比，转基因植物的 POD 活性增加，而 SOD 和 CAT 活性降低。有趣的是，表达 OsHARBI1-1 的拟南芥根中 Cd 的积累显著增加，而地上部 Cd 的积累略有减少。与 WT 植物相比，在 Cd 胁迫下，转基因拟南芥中与 Cd 吸收和螯合相关的基因表达上调，而负责将 Cd 从根部转运到地上部的基因表达下调。此外，在有或没有 Cd 处理的情况下，OsHARBI1-1 的表达对植物激素相关基因的表达有显著影响。
本研究结果表明，OsHARBI1-1 可能通过影响抗氧化酶活性、Cd 螯合、吸收和转运以及植物激素稳态和信号转导，在植物对 Cd 响应中发挥作用。
