Polyamines mitigate the destructive impacts of salinity stress by enhancing photosynthetic capacity, antioxidant defense system and upregulation of calvin cycle-related genes in rapeseed (Brassica napus L.)

Abdelaleim I ElSayed; Azza H Mohamed; Mohammed Suhail Rafudeen; Ahmad A Omar; Mohamed F Awad; Elsayed Mansour

doi:10.1016/j.sjbs.2022.02.053

Polyamines mitigate the destructive impacts of salinity stress by enhancing photosynthetic capacity, antioxidant defense system and upregulation of calvin cycle-related genes in rapeseed (Brassica napus L.)

Saudi J Biol Sci. 2022 May;29(5):3675-3686. doi: 10.1016/j.sjbs.2022.02.053. Epub 2022 Mar 4.

Authors

Abdelaleim I ElSayed¹, Azza H Mohamed^{2

3}, Mohammed Suhail Rafudeen⁴, Ahmad A Omar^{1

3}, Mohamed F Awad⁵, Elsayed Mansour⁶

Affiliations

¹ Biochemistry Department, Faculty of Agriculture, Zagazig University, Zagazig 44519, Egypt.
² Agricultural Chemistry Department, Faculty of Agriculture, Mansoura University, Mansoura 35516, Egypt.
³ Citrus Research and Education Center, University of Florida, IFAS, Lake Alfred, FL 33850, USA.
⁴ Department of Molecular and Cell Biology, University of Cape Town, Private Bag, Rondebosch 7701, South Africa.
⁵ Department of Biology, College of Science, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia.
⁶ Department of Crop Science, Faculty of Agriculture, Zagazig University, Zagazig 44519, Egypt.

Abstract

Salinity is widespread environmental stress that poses great obstacles to rapeseed development and growth. Polyamines are key plant growth regulators that play a pivotal role in regulating salt tolerance. Rapeseed (Brassica napus L.) seedlings were treated by spermine (Spm) and spermidine (Spd) versus untreated control under salt stress conditions. It was detected that the Spd-treated plants had significantly elevated chlorophyll and proline content and maintained higher photosystem II (PSII) activity than those treated with Spm as well as untreated control under salt-stressed conditions. Similarly, Spd alleviated the devastating effects of NaCl stress on CO₂ assimilation and significantly elevated Rubisco activity (ribulose 1,5-bisphosphate carboxylase/oxygenase). The application of Spd also enhanced the activities of different antioxidant enzymes under NaCl stress. It modulated their respective transcription levels, including ascorbate peroxidase (APX), catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR), and dehydroascorbate reductase (DHAR). In addition, exogenously sprayed Spd enhanced the polyamine pathway as observed by upregulated transcription of polyamine oxidase (PAO) and diamine oxidase (DAO). The Spd application enhanced expressions of Calvin cycle enzyme related genes such as Rubisco small subunit, Rubisco large subunit, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), 3-phosphoglyceric acid kinase (PGK), triose-3-phosphate isomerase (TPI), fructose-1,6-bisphosphate aldolase (FBA), sedoheptulose-1,7-bisphosphatase (SBPase), and fructose-1,6-bisphosphate phosphatase (FBPase). Consequently, this study demonstrates that exogenous application of Spd has a valuable role in regulating antioxidant enzyme activity, polyamine pathway, and Calvin cycle enzyme-related genes to alleviate salt stress damage in the plants.

Keywords: Gene expression; Photosynthesis; Rapeseed; Salinity stress; Spermidine; Spermine.