Seed priming with polyethylene glycol regulating the physiological and molecular mechanism in rice (Oryza sativa L.) under nano-ZnO stress.

Sheteiwy Mohamed Salah,Ning Mingyu,Hu Jin,Hu Qijuan,Hu Weimin,Cao Dongdong,Guan Yajing,Nawaz Aamir,Li Jie

doi:10.1038/srep14278

Sheteiwy Mohamed Salah, Ning Mingyu + Show 7 more

Open Access

https://doi.org/10.1038/srep14278

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Abstract

The present study was designed to highlight the impact of seed priming with polyethylene glycol on physiological and molecular mechanism of two cultivars of Oryza sativa L. under different levels of zinc oxide nanorods (0, 250, 500 and 750 mg L−1). Plant growth parameters were significantly increased in seed priming with 30% PEG under nano-ZnO stress in both cultivars. Whereas, this increase was more prominent in cultivar Qian You No. 1 as compared to cultivar Zhu Liang You 06. Significant increase in photosynthetic pigment with PEG priming under stress. Antioxidant enzymes activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) as well as malondialdehyde (MDA) contents were significantly reduced with PEG priming under nano-ZnO stress. Gene expression analysis also suggested that expression of APXa, APXb, CATa, CATb, CATc, SOD1, SOD2 and SOD3 genes were down regulated with PEG priming as compared to non-primed seeds under stress. The ultrastructural analysis showed that leaf mesophyll and root cells were significantly damaged under nano-ZnO stress in both cultivars but the damage was prominent in Zhu Liang You 06. However, seed priming with PEG significantly alleviate the toxic effects of nano-ZnO stress and improved the cell structures of leaf and roots in both cultivars.

Highlights

Seed priming could be defined as a technique that controls the hydration level within seeds induce metabolic activities for germination but radical emergence is prevented
Results demonstrated that a linear decrease was observed in chlorophyll a, chlorophyll b, total chlorophyll and carotenoids contents under different nano-ZnO concentrations in two rice cultivars, this decrease was more pronounced in cultivar Zhu Liang You 06 as compared to cultivar Qian You No 1 (Fig. 1)
Seed priming with Polyethylene glycol (PEG) significantly increased chlorophyll a (Chl a), chlorophyll b (Chl b), total chlorophyll, and carotenoid contents under nano-ZnO stress in leaves of both rice cultivars as compared to control (Fig. 1)

Summary

Introduction

Seed priming could be defined as a technique that controls the hydration level within seeds induce metabolic activities for germination but radical emergence is prevented. Zinc has major contribution to perform biochemical and physiological processes, even slight deficiencies may affect growth and yield. These all evidences inspired us to understand the molecular mechanisms of nano-ZnO uptake, translocation and storing of zinc in rice plants. The induction of antioxidative defense was investigated at enzymatic as well as transcriptional level in order to disclose the toxicity mechanisms of ZnO in rice plants. This approach may enhance our understandings about the toxicity of engineered nanoparticles (ENPs) on this plant species. Thereafter, it could be helpful to improve the plant growth in ZnO polluted soils

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Results

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