Zinc oxide nanoparticles and 24-epibrassinolide alleviates Cu toxicity in tomato by regulating ROS scavenging, stomatal movement and photosynthesis

Mohammad Faizan; Javaid Akhter Bhat; Ahmed Noureldeen; Parvaiz Ahmad; Fangyuan Yu

doi:10.1016/j.ecoenv.2021.112293

Zinc oxide nanoparticles and 24-epibrassinolide alleviates Cu toxicity in tomato by regulating ROS scavenging, stomatal movement and photosynthesis

Ecotoxicol Environ Saf. 2021 May 3:218:112293. doi: 10.1016/j.ecoenv.2021.112293. Online ahead of print.

Authors

Mohammad Faizan¹, Javaid Akhter Bhat², Ahmed Noureldeen³, Parvaiz Ahmad⁴, Fangyuan Yu⁵

Affiliations

¹ Collaborative Innovation Center of Sustainable Forestry in Southern China, College of Forest Science, Nanjing Forestry University, Nanjing 210037, China.
² State Key Laboratory for Crop Genetics and Germplasm Enhancement, College of Agriculture, Nanjing Agricultural University, Nanjing 210095, China. Electronic address: javid.akhter69@gmail.com.
³ Department of Biology, College of Sciences, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia.
⁴ Department of Botany, S.P. College, Srinagar, Jammu and Kashmir, India. Electronic address: parvaizbot@yahoo.com.
⁵ Collaborative Innovation Center of Sustainable Forestry in Southern China, College of Forest Science, Nanjing Forestry University, Nanjing 210037, China. Electronic address: fyyu@njfu.edu.cn.

PMID: 33957422
DOI: 10.1016/j.ecoenv.2021.112293

Abstract

Nanoparticles (NPs) have recently emerged as potential agents for plants to ameliorate abiotic stresses by acting as nano-fertilizers. In this regard, the influence of the zinc oxide nanoparticles (ZnO-NPs) on plant responses to copper (Cu) stress has been poorly understood. Hence, the present study was executed to explore the role of ZnO-NPs (foliar) and 24-epibrassinolide (EBL; root dipping) individually or in combined form in the resilience of tomato (Solanum lycopersicum) plant to Cu stress. Tomato seeds were sown to make the nursery; and at 20 days after sowing (DAS) the plantlets were submerged in 10^-8 M of EBL solution for 2 h, and subsequently transplanted in the soil-filled earthen pots. Cu concentration (100 mg kg^-1) was applied to the soil at 30 DAS, whereas at 35 DAS plants were sprinkled with double distilled water (DDW; control), 50 mg/L of Zinc (Zn) and 50 mg/L of ZnO-NPs; and plant performance were evaluated at 45 DAS. It was evident that Cu-stress reduced photosynthesis (17.3%), stomatal conductance (18.1%), plant height (19.7%), and nitrate reductase (NR) activity (19.2%), but increased malondialdehyde (MDA; 29.4%), superoxide radical (O₂^-; 22.3%) and hydrogen peroxide (H₂O₂; 26.2%) content in S. lycopersicum. Moreover, ZnO-NPs and/or EBL implemented via different modes improved photosynthetic activity, stomatal aperture, growth, cell viability and activity of antioxidant enzymes and proline that augmented resilience of tomato plants to Cu stress. These observations depicted that application of ZnO-NPs and EBL could be a useful approach to assist Cu confiscation and stress tolerance against Cu in tomato plants grown in Cu contaminated sites.

Keywords: 24-epibrassinolide; Antioxidant enzymes; Copper stress; Nanoparticles.