Silicon-induced thermotolerance in Solanum lycopersicum L. via activation of antioxidant system, heat shock proteins, and endogenous phytohormones

Abstract

Background: Abiotic stresses (e.g., heat or limited water and nutrient availability) limit crop production worldwide. With the progression of climate change, the severity and variation of these stresses are expected to increase. Exogenous silicon (Si) has shown beneficial effects on plant growth; however, its role in combating the negative effects of heat stress and their underlying molecular dynamics are not fully understood. Results: Exogenous Si significantly mitigated the adverse impact of heat stress by improving tomato plant biomass, photosynthetic pigments, and relative water content. Si induced stress tolerance by decreasing the concentrations of superoxide anions and malondialdehyde, as well as mitigating oxidative stress by increasing the gene expression for antioxidant enzymes (peroxidases, catalases, ascorbate peroxidases, superoxide dismutases, and glutathione reductases) under stress conditions. This was attributed to increased Si uptake in the shoots via the upregulation of low silicon (SlLsi1 and SlLsi2) gene expression under heat stress. Interestingly, Si stimulated the expression and transcript accumulation of heat shock proteins by upregulating heat transcription factors (Hsfs) such as SlHsfA1a-b, SlHsfA2-A3, and SlHsfA7 in tomato plants under heat stress. On the other hand, defense and stress signaling-related endogenous phytohormones (salicylic acid [SA]/abscisic acid [ABA]) exhibited a decrease in their concentration and biosynthesis following Si application. Additionally, the mRNA and gene expression levels for SA (SlR1b1, SlPR-P2, SlICS, and SlPAL) and ABA (SlNCEDI) were downregulated after exposure to stress conditions. Conclusion: Si treatment resulted in greater tolerance to abiotic stress conditions, exhibiting higher plant growth dynamics and molecular physiology by regulating the antioxidant defense system, SA/ABA signaling, and Hsfs during heat stress.

Investigation of Heat-Induced Changes in the Grain Yield and Grains Metabolites, with Molecular Insights on the Candidate Genes in Barley

“…Proline and protein accumulation conferred heat and drought tolerance in maize during flowering and reproductive stages [51]. Overaccumulation of soluble protein was found to be associated with heat tolerance in tomato (Solanum lycopersicum L.) and wheat [56,57]. These results show the interdependency of the physiological and yield-related traits to ameliorate the deleterious effects of heat stress.…”

Melatonin Ameliorates Thermotolerance in Soybean Seedling through Balancing Redox Homeostasis and Modulating Antioxidant Defense, Phytohormones and Polyamines Biosynthesis

“…Endogenous ABA was quantified and extracted as described previously [ 68 ], with slight modifications reported in a recent study [ 69 ]. ABA was extracted from the aerial parts of the plant (freeze-dried plant samples, 0.3 g), and a chromatograph was run using the Me-[2H6]-ABA standard.…”

“…For chromatographic separation and quantification of the PAs (putrescine [Put], spermine [Spm], spermidine [Spd]), we used a UHPLC instrument (Ultimate 3000, Thermo Scientific, San Jose, CA, USA) equipped with a C18 reversed-phase column and a flow rate of 0.8 mL/min. Endogenous ABA was quantified and extracted as described previously [68], with slight modifications reported in a recent study [69]. ABA was extracted from the aerial parts of the plant (freeze-dried plant samples, 0.…”

Extracellular Fragmented Self-DNA Is Involved in Plant Responses to Biotic Stress

“…Although Hsps play a major role in abiotic stress responses (e.g., to heat) as molecular chaperones, Hsps are involved in protein folding and in avoiding the irreversible aggregation of denatured proteins (Sun et al, 2002). In tomato, the activation of Hsps prevents lipid peroxidation, the generation of excessive reactive radicals and increases the secretion of plant antioxidant enzymes (Khan et al, 2020). Therefore the downregulation of all Hsps in response to eDNA treatment might be associated to the reduced scavenging activity and the increased production of ROS.…”