Silicon enhances plant resistance to Fusarium wilt by promoting antioxidant potential and photosynthetic capacity in cucumber (Cucumis sativus L.)

Shuangsheng Sun; Zhengkun Yang; Zhiyu Song; Nannan Wang; Ning Guo; Jinghan Niu; Airong Liu; Bing Bai; Golam Jalal Ahammed; Shuangchen Chen

doi:10.3389/fpls.2022.1011859

Silicon enhances plant resistance to Fusarium wilt by promoting antioxidant potential and photosynthetic capacity in cucumber (Cucumis sativus L.)

Front Plant Sci. 2022 Oct 13:13:1011859. doi: 10.3389/fpls.2022.1011859. eCollection 2022.

Authors

Shuangsheng Sun¹, Zhengkun Yang¹, Zhiyu Song¹, Nannan Wang¹, Ning Guo¹, Jinghan Niu¹, Airong Liu¹, Bing Bai², Golam Jalal Ahammed^{1

3

4}, Shuangchen Chen^{1

3

4}

Affiliations

¹ College of Horticulture and Plant Protection, Henan University of Science and Technology, Luoyang, China.
² Wageningen Seed Science Centre, Laboratory of Plant Physiology, Wageningen University, Wageningen, Netherlands.
³ Henan International Joint Laboratory of Stress Resistance Regulation and Safe Production of Protected Vegetables, Luoyang, China.
⁴ Henan Engineering Technology Research Center for Horticultural Crop safety and Disease Control, Luoyang, China.

Abstract

Fusarium wilt, caused by Fusarium oxysporum f. sp. cucumerinum (Fo), is a severe soil-borne disease affecting cucumber production worldwide, particularly under monocropping in greenhouses. Silicon (Si) plays an important role in improving the resistance of crops to Fusarium wilt, but the underlying mechanism is largely unclear. Here, an in vitro study showed that 3 mmol·l^-1 Si had the best inhibitory effect on the mycelial growth of F. oxysporum in potato dextrose agar (PDA) culture for 7 days. Subsequently, the occurrence of cucumber wilt disease and its mechanisms were investigated upon treatments with exogenous silicon under soil culture. The plant height, stem diameter, root length, and root activity under Si+Fo treatment increased significantly by 39.53%, 94.87%, 74.32%, and 95.11% compared with Fo only. Importantly, the control efficiency of Si+Fo was 69.31% compared with that of Fo treatment. Compared with Fo, the activities of peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) significantly increased by 148.92%, 26.47%, and 58.54%, while the contents of H₂O₂, $O_{2}^{\cdot -}$ , and malondialdehyde (MDA) notably decreased by 21.67%, 59.67%, and 38.701%, respectively, in roots of cucumber plants treated with Si + Fo. Compared with Fo treatment, the net photosynthesis rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), maximum RuBisCO carboxylation rates (Vcmax), maximum RuBP regeneration rates (Jmax), and activities of ribulose-1,5-bisphosphate carboxylase (RuBisCO), fructose-1,6-bisphosphatase (FBPase), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and the expression of FBPA, TPI, SBPase, and FBPase in Si+Fo treatment increased significantly. Furthermore, Si alleviated stomatal closure and enhanced endogenous silicon content compared with only Fo inoculation. The study results suggest that exogenous silicon application improves cucumber resistance to Fusarium wilt by stimulating the antioxidant system, photosynthetic capacity, and stomatal movement in cucumber leaves. This study brings new insights into the potential of Si application in boosting cucumber resistance against Fusarium wilt with a bright prospect for Si use in cucumber production under greenhouse conditions.

Keywords: Fusarium oxysporum; antioxidant system; cucumber; photosynthesis; silicon.