Beneficial effects of silicon on photosynthesis of tomato seedlings under water stress

Abstract

Silicon can improve drought tolerance of plants, but the mechanism still remains unclear. Previous studies have mainly concentrated on silicon-accumulating plants, whereas less work has been conducted in silicon-excluding plants, such as tomato (Solanum lycopersicum L.). In this study, we investigated the effects of exogenous silicon (2.5 mmol L-1) on the chlorophyll fluorescence and expression of photosynthesis-related genes in tomato seedlings (Zhongza 9) under water stress induced by 10% (w/v) polyethylene glycol (PEG-6000). The results showed that under water stress, the growth of shoot and root was inhibited, and the chlorophyll and carotenoid concentrations were decreased, while silicon addition improved the plant growth and increased the concentrations of chlorophyll and carotenoid. Under water sterss, chlorophyll fluorescence parameters such as PSII maximum photochemical efficiency (F v /F m), effective quantum efficiency, actual photochemical quantum efficiency (Ф PSII), photosynthetic electron transport rate (ETR), and photochemical quenching coefficient (q P) were decreased; while these changes were reversed in the presence of added silicon. The expressions of some photosynthesis-related genes including PetE, PetF, PsbP, PsbQ, PsbW, and Psb28 were down-regulated under water stress, and exogenous Si could partially up-regulate their expressions. These results suggest that silicon plays a role in the alleviation of water stress by modulating some photosynthesis-related genes and regulating the photochemical process, and thus promoting photosynthesis.

Integrative Effects of Rice-Straw Biochar and Silicon on Oil and Seed Quality, Yield and Physiological Traits of Helianthus annuus L. Grown under Water Deficit Stress

“…The increased chlorophyll content in the current study upon the application of silicon and biochar under water deficit stress conditions might be associated with improved antioxidant defense and therefore maintained physiological processes such as photosynthesis. Zhang et al [29] have reported that the expression of some photosynthesis-related genes are down-regulated in plants grown under water deficit stress conditions; however, exogenous Si can partly up-regulate their expression. This result suggests that Si plays a vital role in alleviating the effect of water deficit stress by modulating photosynthesis-related genes, regulating photochemical process and promoting photosynthesis [29].…”

“…Zhang et al [29] have reported that the expression of some photosynthesis-related genes are down-regulated in plants grown under water deficit stress conditions; however, exogenous Si can partly up-regulate their expression. This result suggests that Si plays a vital role in alleviating the effect of water deficit stress by modulating photosynthesis-related genes, regulating photochemical process and promoting photosynthesis [29]. Under water stress, photosynthesis in the sunflower plant can be affected by two mechanisms-(a) reduced CO 2 diffusion within the leaf owing to closure of stomata and (b) metabolic inhibition of CO 2 [61].…”

“…Silicon can enhance resistance of plants to diseases caused by fungi or bacteria [25] through structural reinforcement [26], inhibiting pathogen colonization, antimicrobial compound production [27] and increasing plant resistance through activating signaling pathways and defense-related gene expression [28]. In addition, silicon can ameliorate harmful effects of various environmental stresses on plant growth and productivity [15,17,29]. It can enhance plant growth under drought stress [29,30] by maintaining plant water balance [31], photosynthetic efficiency, erectness of leaves and the structure of xylem vessels under high transpiration rates caused by high temperature and moisture stress [29,32,33].…”

“…In addition, silicon can ameliorate harmful effects of various environmental stresses on plant growth and productivity [15,17,29]. It can enhance plant growth under drought stress [29,30] by maintaining plant water balance [31], photosynthetic efficiency, erectness of leaves and the structure of xylem vessels under high transpiration rates caused by high temperature and moisture stress [29,32,33]. Silicate minerals accumulate in epidermal cells to form a barrier and reduce water loss using the cuticles [34].…”

Management of Heat Stress in Tomato Seedlings under Arid and Semi-Arid Regions: A Review

“…This Solanaceous seedling has categorized as an important model plant in investigating the stress tolerance (Zhang et al, 2018). So, several stress studies have been carried on tomato seedlings such as heat stress (Lyu et al, 2018), water stress (Zhang et al 2018), drought (Bian et al, 2019), salinity (Zhou et al 2019), UV-B stress (Liu et al, 2020), chilling (Dong et al, 2020), and waterlogging (Elkelish et al, 2020). Many strategies could be adapted to overcome these stresses depending on the kind of stress, cultivated plants and its growth stage (Zhou et al, 2020).…”