Selenium nanoparticles conferred drought tolerance in tomato plants by altering the transcription pattern of microRNA-172 (miR-172), bZIP, and CRTISO genes, upregulating the antioxidant system, and stimulating secondary metabolism.

Drought stress is one of the major limiting factors for the production of tomato in Iran. In this study, the efficiency of selenate and Se nanoparticle (SeNP) foliar application on tomato plants was assessed to vestigate mitigating the risk associated with water-deficit conditions. Tomato plants were treated with SeNPs at the concentrations of 0 and 4 mg L-1; after the third sprays, the plants were exposed to water-deficit conditions. The foliar spraying with SeNPs not only improved growth, yield, and developmental switch to the flowering phase but also noticeably mitigated the detrimental risk associated with the water-deficit conditions. Gene expression experiments showed a slight increase in expression of microRNA-172 (miR-172) in the SeNP-treated plants in normal irrigation, whereas miR-172 displayed a downregulation trend in response to drought stress. The bZIP transcription factor and CRTISO genes were upregulated following the SeNP and drought treatments. Drought stress significantly increased the H2O2 accumulation that is mitigated with SeNPs. The foliar spraying with Se or SeNPs shared a similar trend to alleviate the negative effect of drought stress on the membrane integrity. The applied supplements also conferred drought tolerance through noticeable improvements in the non-enzymatic (ascorbate and glutathione) and enzymatic (catalase and peroxidase) antioxidants. The SeNP-mediated improvement in drought stress tolerance correlated significantly with increases in the activity of phenylalanine ammonia-lyase, proline, non-protein thiols, and flavonoid concentrations. SeNPs also improved the fruit quality regarding K, Mg, Fe, and Se concentrations. It was concluded that foliar spraying with SeNPs could mitigate the detrimental risk associated with the water-deficit conditions.

Correction: Comparative efficacy of selenate and selenium nanoparticles for improving growth, productivity, fruit quality, and postharvest longevity through modifying nutrition, metabolism, and gene expression in tomato; potential benefits and risk assessment.

[This corrects the article DOI: 10.1371/journal.pone.0244207.].

Comparative efficacy of selenate and selenium nanoparticles for improving growth, productivity, fruit quality, and postharvest longevity through modifying nutrition, metabolism, and gene expression in tomato; potential benefits and risk assessment.

This study attempted to address molecular, developmental, and physiological responses of tomato plants to foliar applications of selenium nanoparticles (nSe) at 0, 3, and 10 mgl-1 or corresponding doses of sodium selenate (BSe). The BSe/nSe treatment at 3 mgl-1 increased shoot and root biomass, while at 10 mgl-1 moderately reduced biomass accumulation. Foliar application of BSe/nSe, especially the latter, at the lower dose enhanced fruit production, and postharvest longevity, while at the higher dose induced moderate toxicity and restricted fruit production. In leaves, the BSe/nSe treatments transcriptionally upregulated miR172 (mean = 3.5-folds). The Se treatments stimulated the expression of the bZIP transcription factor (mean = 9.7-folds). Carotene isomerase (CRTISO) gene was transcriptionally induced in both leaves and fruits of the nSe-treated seedlings by an average of 5.5 folds. Both BSe or nSe at the higher concentration increased proline concentrations, H2O2 accumulation, and lipid peroxidation levels, suggesting oxidative stress and impaired membrane integrity. Both BSe or nSe treatments also led to the induction of enzymatic antioxidants (catalase and peroxidase), an increase in concentrations of ascorbate, non-protein thiols, and soluble phenols, as well as a rise in the activity of phenylalanine ammonia-lyase enzyme. Supplementation at 3 mgl-1 improved the concentration of mineral nutrients (Mg, Fe, and Zn) in fruits. The bioaccumulated Se contents in the nSe-treated plants were much higher than the corresponding concentration of selenate, implying a higher efficacy of the nanoform towards biofortification programs. Se at 10 mgl-1, especially in selenate form, reduced both size and density of pollen grains, indicating its potential toxicity at the higher doses. This study provides novel molecular and physiological insights into the nSe efficacy for improving plant productivity, fruit quality, and fruit post-harvest longevity.