Over-expression of spermidine synthase 2 (SlSPDS2) in tomato plants improves saline-alkali stress tolerance by increasing endogenous polyamines content to regulate antioxidant enzyme system and ionic homeostasis

Pengju Wang; Zijian Xu; Yong Zhang; Yongbo Ma; Jianyu Yang; Fan Zhou; Yi Gao; Guobin Li; Xiaohui Hu

doi:10.1016/j.plaphy.2022.09.025

Over-expression of spermidine synthase 2 (SlSPDS2) in tomato plants improves saline-alkali stress tolerance by increasing endogenous polyamines content to regulate antioxidant enzyme system and ionic homeostasis

Plant Physiol Biochem. 2022 Dec 1:192:172-185. doi: 10.1016/j.plaphy.2022.09.025. Epub 2022 Oct 3.

Authors

Pengju Wang¹, Zijian Xu¹, Yong Zhang¹, Yongbo Ma¹, Jianyu Yang¹, Fan Zhou¹, Yi Gao¹, Guobin Li², Xiaohui Hu³

Affiliations

¹ College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, China; Key Laboratory of Protected Horticultural Engineering in Northwest, Ministry of Agriculture, Yangling, Shaanxi, 712100, China; Shaanxi Protected Agriculture Research Centre, Yangling, Shaanxi, 712100, China.
² College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, China; Key Laboratory of Protected Horticultural Engineering in Northwest, Ministry of Agriculture, Yangling, Shaanxi, 712100, China; Shaanxi Protected Agriculture Research Centre, Yangling, Shaanxi, 712100, China. Electronic address: 15071491276@163.com.
³ College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, China; Key Laboratory of Protected Horticultural Engineering in Northwest, Ministry of Agriculture, Yangling, Shaanxi, 712100, China; Shaanxi Protected Agriculture Research Centre, Yangling, Shaanxi, 712100, China. Electronic address: hxh1977@163.com.

PMID: 36244190
DOI: 10.1016/j.plaphy.2022.09.025

Abstract

Endogenous spermidine can improve the resistance of plants to saline-alkali stress. SlSPDS1 and SlSPDS2 are the main spermidine synthase (SPDS) genes in tomatoes. In comparison with SlSPDS1, SlSPDS2 plays an important role in wild-type tomato seedling under saline-alkali stress. However, limited research has focused on the role of SlSPDS2 in saline-alkali stress. Wild-type (WT) and SPDS gene (SlSPDS2) transgenic over-expression tomato seedlings were used to explore the function of endogenous spermidine on the saline-alkali resistance of tomato seedlings. The results show that SlSPDS2 overexpression under normal conditions and saline-alkali stress increased the content of endogenous free polyamines and the expression levels of polyamine synthesis-related genes in tomato seedlings. Under saline-alkali stress, SlSPDS2 overexpression significantly reduced Na⁺/K⁺ ratio, relative electrical conductivity, O₂^·-, H₂O₂, and malondialdehyde content, increased Seedling index, relative water content, antioxidant enzyme activities (peroxidase, superoxide dismutase, and catalase), and the contents of proline and soluble sugar in tomato leaf, and mitigated the adverse effect of saline-alkali stress on tomato seedlings. In summary, the overexpression of SlSPDS2 tomato seedlings regulated the ionic homeostasis, antioxidant enzyme system, and osmotic regulatory substances of tomato seedlings living in saline-alkali environment by increasing endogenous free polyamine content, thereby improving the resistance of tomato seedlings against saline-alkali stress.

Keywords: Antioxidant enzymes; Ion homeostasis; Polyamines; Saline-alkali stress; SlSPDS2; Solanum lycopersicum.