Selenium Modulates the Level of Auxin to Alleviate the Toxicity of Cadmium in Tobacco

Luo Luo,Han Han,Wei Wei,Wang Wang,Fu Fu,Jia Jia,Shao Shao,Sun Sun

doi:10.3390/ijms20153772

Luo Luo, Han Han + Show 6 more

Open Access

https://doi.org/10.3390/ijms20153772

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Abstract

Cadmium (Cd) is an environmental pollutant that potentially threatens human health worldwide. Developing approaches for efficiently treating environmental Cd is a priority. Selenium (Se) plays important role in the protection of plants against various abiotic stresses, including heavy metals. Previous research has shown that Se can alleviate Cd toxicity, but the molecular mechanism is still not clear. In this study, we explore the function of auxin and phosphate (P) in tobacco (Nicotiana tabacum), with particular focus on their interaction with Se and Cd. Under Cd stress conditions, low Se (10 μM) significantly increased the biomass and antioxidant capacity of tobacco plants and reduced uptake of Cd. We also measured the auxin concentration and expression of auxin-relative genes in tobacco and found that plants treated with low Se (10 μM) had higher auxin concentrations at different Cd supply levels (0 μM, 20 μM, 50 μM) compared with no Se treatment, probably due to increased expression of auxin synthesis genes and auxin efflux carriers. Overexpression of a high affinity phosphate transporter NtPT2 enhanced the tolerance of tobacco to Cd stress, possibly by increasing the total P and Se content and decreasing Cd accumulation compared to that in the wild type (WT). Our results show that there is an interactive mechanism among P, Se, Cd, and auxin that affects plant growth and may provide a new approach for relieving Cd toxicity in plants.

Highlights

Cadmium (Cd) is a highly toxic heavy metal, which is widely distributed in the environment [1]
To determine whether Se affects the growth of tobacco under different Cd treatments, we checked the characterization of tobacco plants
We found that low Se (Se10) could promote the growth of tobacco under Cd stress (Figure 1A); under Cd20 and Cd50 stress conditions, the biomass of shoots with Se10 treatments increased by 16.3% and 20.8%, respectively, compared to those with no Se added (Figure 1B), and the biomass of roots with Se10 treatments increased by 24.2% and 30.2%, respectively (Figure 1C)

Summary

Introduction

Cadmium (Cd) is a highly toxic heavy metal, which is widely distributed in the environment [1]. Cd is not needed for plant growth and development but is more likely to accumulate in plants than other heavy metals [3]. Evidence suggests that a high concentration of Cd in soil affects the growth and development of plants through physiological and biochemical processes, including inhibition of plant enzyme and membrane activity [4], decreased cell division [5], reduced growth rate [6], damaged photosynthesis [7], inhibition of stomatal opening [8], and promotion of lipid peroxidation [9]. Soil pollution by Cd has become a serious threat to the safety of agricultural produce To address this issue, it is important to develop a comprehensive understanding of the mechanism of Cd uptake in plants. Recent research suggests that auxin is involved in the interaction between Pi and Se in tobacco, which provides convincing evidence for understanding the molecular mechanism of how Se regulates plant growth [16]

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Conclusion