Variety-dependent responses of common tobacco with differential cadmium resistance: Cadmium uptake and distribution, antioxidative activity, and gene expression.

Cadmium (Cd), which accumulates in tobacco leaves, enters the human body through inhalation of smoke, causing harmful effects on health. Therefore, identifying the pivotal factors that govern the absorption and resistance of Cd in tobacco is crucial for mitigating the harmful impact of Cd. In the present study, four different Cd-sensitive varieties, namely, ZhongChuan208 (ZC) with resistance, ZhongYan100 (ZY), K326 with moderate resistance, and YunYan87 (YY) with sensitivity, were cultivated in hydroponic with different Cd concentrations (20 µM, 40 µM, 60 µM and 80 µM). The results indicated that plant growth was significantly decreased by Cd. Irrespective of the Cd concentration, ZC exhibited the highest biomass, while YY had the lowest biomass; ZY and K326 showed intermediate levels. Enzymatic (APX, CAT, POD) and nonenzymatic antioxidant (Pro, GSH) systems showed notable variations among varieties. The multifactor analysis suggested that the ZC and ZY varieties, with higher levels of Pro and GSH content, contribute to a decrease in the levels of MDA and ROS. Among all the Cd concentrations, ZC exhibited the lowest Cd accumulation, while YY showed the highest. Additionally, there were significant differences observed in Cd distribution and translocation factors among the four different varieties. In terms of Cd distribution, cell wall Cd accounted for the highest proportion of total Cd, and organelles had the lowest proportion. Among the varieties, ZC showed lower Cd levels in the cell wall, soluble fraction, and organelles. Conversely, YY exhibited the highest Cd accumulation in all tissues; K326 and ZY had intermediate levels. Translocation factors (TF) varied among the varieties under Cd stress, with ZC and ZY showing lower TF compared to YY and K326. This phenomenon mainly attributed to regulation of the NtNramp3 and NtNramp5 genes, which are responsible for the absorption and transport of Cd. This study provides a theoretical foundation for the selection and breeding of tobacco varieties that are resistant to or accumulate less Cd.

Aquaporin mediated silicon-enhanced root hydraulic conductance is benefit to cadmium dilution in tobacco seedlings.

Numerous studies shown that silicon (Si) enhanced plants' resistance to cadmium (Cd). Most studies primarily focused on investigating the impact of Si on Cd accumulation. However, there is a lack of how Si enhanced Cd resistance through regulation of water balance. The study demonstrated that Si had a greater impact on increasing fresh weight compared to dry weight under Cd stress. This effect was mainly attributed to Si enhanced plant relative water content (RWC). Plant water content depends on the dynamic balance of water loss and water uptake. Our findings revealed that Si increased transpiration rate and stomatal conductance, leading to higher water loss. This, in turn, negatively impacted water content. The increased water content caused by Si could ascribe to improve root water uptake. The Si treatment significantly increased root hydraulic conductance (Lpr) by 131 % under Cd stress. This enhancement was attributed to Si upregulation genes expression of NtPIP1;1, NtPIP1;2, NtPIP1;3, and NtPIP2;1. Through meticulously designed scientific experiments, this study showed that Si enhanced AQP activity, leading to increased water content that diluted Cd concentration and ultimately improved plant Cd resistance. These findings offered fresh insights into the role of Si in bolstering plant resistance to Cd.

Effect and mechanism of nano-materials on plant resistance to cadmium toxicity: A review.

Cadmium (Cd), one of the most toxic heavy metals, has been extensively studied by environmental scientists because of its detrimental effects on plants, animals, and humans. Increased industrial activity has led to environmental contamination with Cd. Cadmium can enter the food chain and pose a potential human health risk. Therefore, reducing the accumulation of Cd in plant species and enhancing their detoxification abilities are crucial for remediating heavy metal pollution in contaminated areas. One innovative technique is nano-phytoremediation, which employs nanomaterials ranging from 1 to 100 nm in size to mitigate the accumulation and detrimental effects of Cd on plants. Although extensive research has been conducted on using nanomaterials to mitigate Cd toxicity in plants, it is important to note that the mechanism of action varies depending on factors such as plant species, level of Cd concentration, and type of nanomaterials employed. This review aimed to consolidate and organize existing data, providing a comprehensive overview of the effects and mechanisms of nanomaterials in enhancing plant resistance to Cd. In particular, its deep excavation the mechanisms of detoxification heavy metals of nanomaterials by plants, including regulating Cd uptake and distribution, enhancing antioxidant capacity, regulating gene expression, and regulating physiological metabolism. In addition, this study provides insights into future research directions in this field.