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

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, O2·−, 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.

Physiological and Biochemical Aspects of Silicon-Mediated Resistance in Maize against Maydis Leaf Blight

“…Rice plants supplied with Si showed increased sucrose concentration in response to B. oryzae infection [ 38 ]. The expression of Calvin cycle-related genes such as those coding for fructose-1,6-bisphosphate aldolase, phosphate isomerase, sedoheptulose-1,7-bisphosphatase, glyceraldehyde-3-phosphate dehydrogenase, fructose-1,6-bisphosphatase, and RuBisCO was repressed in cucumber plants infected with Fusarium oxysporum [ 39 ]. However, the expression of the genes mentioned above increased and improved the pool of soluble sugars and the resistance of cucumber against Fusarium wilt for Si-supplied plants.…”

“…In addition, SOD, APX, CAT, and GR activities were greatest earlier in the B. maydis infection process while SOD, CAT, and GR activities were higher at the advanced stage of fungal infection. Other studies showed that Si can stimulate the enzymatic antioxidant metabolism of pathogen-challenged plants by restricting the oxidative stress caused by an excess of ROS associated with less lipid peroxidation in the infected cells [ 12 , 13 , 17 , 20 , 39 , 43 ]. In the present study, APX activity was higher for infected −Si plants in contrast to infected +Si plants from 60 to 156 hai, possibly due to the higher availability of H 2 O 2 that needed detoxification.…”

Pengaruh Trichoderma harzianum dan Nano Silika Terhadap Penyakit Moler dan Produksi Bawang Merah

“…Aplikasi silika mampu meningkatkan kandungan fenol, flavonoid, lignin, dan dopamin (Fortunato et al 2014) atau menginduksi pembentukan enzim, hormon dan senyawa anti jamur berupa aglikon dan fitoaleksin yang dapat meningkatkan resistensi tanaman (Ahammed dan Yang 2021) terserang penyakit, sehingga meskipun telah terinfeksi kerusakannya akan rendah. Penggunaan silika mampu menghambat serangan bercak ungu bawang merah (Hersanti et al 2019), busuk akar putih bawang merah (Elshahawy et al 2021), dan fusarium pada tanaman pisang (Fortunato et al 2014) dan mentimun (Sun et al 2022).…”

Silicon-Induced Morphological, Biochemical and Molecular Regulation in Phoenix dactylifera L. under Low-Temperature Stress

“…It is not yet considered an essential nutrient but has proved to play an extensive plant-growth-promoting role, particularly in stress conditions [ 23 , 25 ]. The role of Si application in mitigating or neutralizing harmful effects has subsequently been disclosed for several stresses, including temperature [ 26 ], salinity and drought [ 25 , 27 ], heavy metals stress [ 28 ], and diseases in plants [ 29 ]. Additionally, it is also known for playing a vital role in improving nutrient deficiencies in plants, including potassium [ 30 ] and iron [ 31 ].…”