State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou 510642, China; Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China; Guangdong Provincial Key Laboratory of Plant Molecular Breeding, South China Agricultural University, Guangzhou 510642, China; College of Agriculture, South China Agricultural University, Guangzhou 510642, China.
Department of Environmental Sciences, Government College University, Faisalabad 38000, Pakistan.
Sci Total Environ. 2024 Feb 10;911:168709. doi: 10.1016/j.scitotenv.2023.168709. Epub 2023 Nov 21.
Lead is a very toxic and futile heavy metal for rice plants because of its injurious effects on plant growth and metabolic processes. Polyploidy or whole genome doubling increases the ability of plants to withstand biotic and abiotic stress. Considering the beneficial effects of nanoparticles and tetraploid rice, this research was conducted to examine the effectiveness of tetraploid and titanium dioxide nanoparticles (TiO NPs) in mitigating the toxic effects of lead. A diploid (E22-2x) and it's tetraploid (T-42) rice line were treated with Pb (200 μM) and TiO NPs (15 mg L). Lead toxicity dramatically reduced shoot length (16 % and 4 %) and root length (17 % and 9 %), biological yield (55 % and 36 %), and photosynthetic activity, as evidenced by lower levels of chlorophyll a and b (30 % and 9 %) in E-22 and T-42 rice cultivars compared to the control rice plants, respectively. Furthermore, lead toxicity amplified the levels of reactive oxygen species (ROS), such as malondialdehyde and HO, while decreasing activities of all antioxidant enzymes, such as superoxidase, peroxidase, and glutathione predominately in the diploid cultivar. Transmission electron microscopy and semi-thin section observations revealed that Pb-treated cells in E22-2x had more cell abnormalities than T-42, such as irregularly shaped mitochondria, cell wall, and reduced root cell size. Polyploidy and TiO reduced Pb uptake in rice cultivars and expression levels of metal transporter genes such as OsHMA9 and OsNRAMP5. According to the findings, genome doubling alleviates Pb toxicity by reducing Pb accumulation, ROS, and cell damage. Tetraploid rice can withstand the toxic effect of Pb better than diploid rice, and TiO NPs can alleviate the toxic impact of Pb. Our study findings act as a roadmap for future research endeavours, directing the focus toward risk management and assessing long-term impacts to balance environmental sustainability and agricultural growth.
铅是一种对植物生长和代谢过程有损害作用的剧毒和无效重金属。多倍体或全基因组加倍增加了植物抵御生物和非生物胁迫的能力。考虑到纳米粒子和四倍体水稻的有益效果，本研究旨在探讨四倍体和二氧化钛纳米粒子（TiO NPs）在减轻铅毒性方面的有效性。二倍体（E22-2x）和它的四倍体（T-42）水稻系用 Pb（200 μM）和 TiO NPs（15 mg L）处理。铅毒性显著降低了茎长（16%和 4%）和根长（17%和 9%）、生物产量（55%和 36%）和光合活性，与对照水稻相比，E-22 和 T-42 水稻品种的叶绿素 a 和 b 水平分别降低了 30%和 9%。此外，铅毒性放大了活性氧（ROS）的水平，如丙二醛和 HO，同时降低了所有抗氧化酶的活性，如超氧化物歧化酶、过氧化物酶和谷胱甘肽，主要在二倍体品种中。透射电子显微镜和半薄切片观察显示，Pb 处理的 E22-2x 细胞比 T-42 细胞具有更多的细胞异常，如不规则形状的线粒体、细胞壁和根细胞大小减小。多倍体和 TiO 减少了水稻品种中 Pb 的吸收和金属转运基因如 OsHMA9 和 OsNRAMP5 的表达水平。根据研究结果，基因组加倍通过减少 Pb 积累、ROS 和细胞损伤来缓解 Pb 毒性。四倍体水稻比二倍体水稻更能耐受 Pb 的毒性，TiO NPs 可以缓解 Pb 的毒性影响。我们的研究结果为未来的研究工作提供了路线图，重点关注风险管理和评估对环境可持续性和农业增长的长期影响。
