Oligochitosan fortifies antioxidative and photosynthetic metabolism and enhances secondary metabolite accumulation in arsenic-stressed peppermint

Bilal Ahmad; Tariq Ahmad Dar; M Masroor A Khan; Ajaz Ahmad; Jörg Rinklebe; Yinglong Chen; Parvaiz Ahmad

doi:10.3389/fpls.2022.987746

Oligochitosan fortifies antioxidative and photosynthetic metabolism and enhances secondary metabolite accumulation in arsenic-stressed peppermint

Front Plant Sci. 2022 Oct 11:13:987746. doi: 10.3389/fpls.2022.987746. eCollection 2022.

Authors

Bilal Ahmad^{1

2}, Tariq Ahmad Dar^{1

2}, M Masroor A Khan¹, Ajaz Ahmad³, Jörg Rinklebe^{4

5}, Yinglong Chen⁶, Parvaiz Ahmad⁷

Affiliations

¹ Department of Botany, Aligarh Muslim University, Aligarh, India.
² Department of Botany, Government Degree College for Women, University of Kashmir, Pulwama, India.
³ Department of Clinical Pharmacy, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia.
⁴ Laboratory of Soil- and Groundwater-Management, School of Architecture and Civil Engineering, Institute of Soil Engineering, Waste- and Water Science, University of Wuppertal, Wuppertal, Germany.
⁵ International Research Centre of Nanotechnology for Himalayan Sustainability (IRCNHS), Shoolini University, Solan, India.
⁶ The UWA Institute of Agriculture, and School of Agriculture and Environment, The University of Western Australia, Perth, WA, Australia.
⁷ Department of Botany, Jammu and Kashmir, India.

Abstract

The current study was designed to investigate whether application of irradiated chitosan (ICn), a recently established plant growth promoter, can prove effective in alleviating arsenic (As) stress in peppermint, a medicinally important plant. This study investigated how foliar application of ICn alleviated As toxicity in peppermint (Mentha piperita L.). Peppermint plants were treated with ICn (80 mg L^-1) alone or in combination with As (10, 20, or 40 mg kg^-1 of soil, as Na₂HAsO₄·7H₂O) 40 days after transplantation (DAT), and effects on the growth, photosynthesis, and antioxidants were assessed at 150 DAT as stress severely decreases plant growth, affects photosynthesis, and alters enzymatic (ascorbate peroxidase, superoxide dismutase) and non-enzymatic (glutathione) antioxidants. When applied at 40 mg kg^-1, ICn significantly decreased the content of essential oil (EO) and total phenols in peppermint by 13.8 and 16.0%, respectively, and decreased phenylalanine ammonia lyase (PAL) and deoxy-D-xylulose-5-phosphate reductoisomerase (DXR) activities by 12.8 and 14.6%, respectively. Application of ICn mitigated the disadvantageous effects caused by As toxicity in peppermint by enhancing activities of antioxidative enzymes and photosynthesis and increased accretion of secondary metabolism products (EOs and phenols). An enhancement of total phenols (increased by 17.3%) and EOs (36.4%) is endorsed to ICn-stimulated enhancement in the activities of PAL and DXR (65.9 and 28.9%, respectively) in comparison to the control. To conclude, this study demonstrated that foliar application of ICn (80 mgL^-1) effectively promoted the growth and physiology of peppermint and eliminated As-induced toxicity to achieve high production of EO-containing crops grown in metal-contaminated soils.

Keywords: arsenic (As) toxicity; chitosan; enzymatic (ascorbate peroxidase; non-enzymatic (glutathione) antioxidants; peppermint; superoxide dismutase) antioxidants.