Impact of Pb on Chlamydomonas reinhardtii at Physiological and Transcriptional Levels

Canqi Zheng,Ping Li,Nan Huang,Kaiming Tang,Muhammad Aslam,Haojie Jia,Hong Du,Yingquan Yang,Xihui Xie,Xiaojuan Liu

doi:10.3389/fmicb.2020.01443

Abstract

Trace elements stress is one of the most damaging abiotic stresses in environment. Nevertheless, the defense mechanism in microalgae remains poorly understood. In this study, physiological and molecular methods were performed to analyze the defense responses in green alga Chlamydomonas reinhardtii. It was speculated that the defense responses might mainly be due to the regulation of hormone signaling, indicating its potential role in alleviating the Pb toxicity besides other physiological and molecular defense responses like decrease in growth rate, chlorophyll content and photosynthesis efficiency, intensification of antioxidative mechanisms, regulation of transcription factors, trace elements chelation, and sequestration into vacuole via trace elements transporters. The sole differentially expressed ATP-binding cassette (ABC) transporters indicated that ABC transporters might play a very important role in the transport and relocation of Pb in C. reinhardtii. Additionally, our data provide the required knowledge for future investigations regarding Pb toxicity and defense mechanisms in algae, and detection of trace elements pollution in environment.

Highlights

Trace elements pollution has attracted the global attentions due to their adverse effects, the developing world which has witnessed rapid development of industry, and opted for modern agricultural technologies (Kavamura and Esposito, 2011; Miransari, 2011; Singh et al, 2016)
To investigate the response of C. reinhardtii under the lead treatment, some key physiological parameters were measured throughout the experiment (Figure 1)
The both total chlorophyll content and Fv/Fm of algae under 80 μmol.L−1 lead treatment were significantly declined on the 1/2 day (P < 0.05) with extremely significant declined demonstration on the 1st, 3rd, 5th, and 7th days (P < 0.01) (Figure 1)

Summary

Introduction

Trace elements pollution has attracted the global attentions due to their adverse effects, the developing world which has witnessed rapid development of industry, and opted for modern agricultural technologies (Kavamura and Esposito, 2011; Miransari, 2011; Singh et al, 2016). (Singh et al, 2016; Du et al, 2018) Suitable amount of these essential trace elements play number of important roles in physiological and biochemical processes of living organisms such as the biosynthesis of pigments, the efficiency of photosynthesis, the growth and development, the synthesis of DNA and other metabolites, and the modification of. It have been demonstrated that non-essential trace elements inhibit the growth of plants, lead to oxidative stress by the accumulation of reactive oxygen species at the cellular level, and damage macromolecules such as lipids, proteins and nucleic acids in cells (Hall, 2002; Sharma and Dietz, 2009; Hossain and Komatsu, 2013). Cd was previously thought to be a nonessential trace element, but recently, it was reported that Cd could be a cofactor in metalloenzymes (e.g., carbonic anhydrases) and decided the activity of total metalloenzymes in algae (Jensen et al, 2020)

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Conclusion