Targeting Cd coping mechanisms for stress tolerance in Brassica napus under spiked-substrate system: from physiology to remediation perspective

Abstract

Cadmium (Cd) is a prevalent, non-essential, carcinogenic, and hazardous heavy metal that reduces plant productivity and capacity of arable land area around the globe. In the present substrate-based pot study, seedlings of Brassica napus 180015 were grown equidistantly in the spiked-substrate medium for 60 days under increasing concentrations of Cd (0, 10, 20, 30, 40, 50 mg kg⁻¹). Following harvest, the morpho-physio-biochemical, antioxidative, and Cd-induced tolerance responses were evaluated in B. napus under an increasing Cd stress regime. Additionally, these parameters were also investigated to select the plant's threshold tolerance limit for Cd under the spiked-substrate system. B. napus showed dynamic behavior regarding morpho-physio-biochemical attributes, including agronomic features, biomass, photosynthetic pigments, relative water content under increased Cd toxicity. Cd stress-induced hydrogen peroxide (H₂O₂) production with high MDA contents and passive EL, followed by the orchestration of both enzymatic (SOD, POD, APX, CAT, and GR) and non-enzymatic antioxidants (flavonoids, TPC, TPA, proline, and total soluble protein) up to a certain limit. In addition, Cd-induced stress upregulated transcriptional levels of antioxidative enzyme SOD, POD, APX, GR, and MT encoded genes in B. napus. The increasing trend of Cd accumulation in different tissues at the highest Cd concentration was as follows: root > leaf > stem. In spiked substrate system, B. napus demonstrated improved metal extractability performance and a high potential for phyto-management of low to moderate Cd contamination, implying that this study could be used for integrative breeding programs and decontaminating heavy metals in real contaminated scenarios.

Novelty statement

This study provides an insight into Cd-coping mechanisms of oilseed rape involved in alleviating toxicity and simultaneous phyto-management of increasing Cd concentration under spiked substrate system. The current study is the first scientific evidence of using a Cd-spiked soilless substrate medium. The present study will further strengthen our understanding of Cd-instigated positive responses in B. napus. Furthermore, it will provide a useful basis for integrative breeding programs and decontaminating heavy metals in real contaminated scenarios.

 

Keywords:

• Antioxidants
• Brassica napus
• cadmium
• induced stress
• metal-generated ROS
• phyto-management

Author’s contribution

Saiqa Menhas: Data curation, Formal and software analysis, Writing—original draft. Xijia Yang: Methodology, Project administration, Conceptualization. Kashif Hayat: Investigation, Data curation, Writing—review and editing. Nabeel Khan Niazi, Sikandar Hayat, Amna, Tariq Aftab and Nan Hui: Writing—review and editing. Juncai Wang and Xunfeng Chen: Review and editing. Pei Zhou: Conceptualization, Funding acquisition, Writing—review and editing.

Acknowledgments

The authors are thankful to all the anonymous reviewers, research team, and funding agencies. We thank Xirong Zhou for providing seeds of Brassica napus.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Shanghai Agriculture Applied Technology Development Program, China [Grant No. T20180413], National Key Research and Development Program of China [Grant No. 2016YFD0800807], Shanghai Science and Technology Innovation Action Project [Grant No. 20392001000, 20dz1204804] and Project of Key Laboratory of Urban Agriculture in North China in 2020 [Grant No. KF2020012].