Nano-Priming for Inducing Salinity Tolerance, Disease Resistance, Yield Attributes, and Alleviating Heavy Metal Toxicity in Plants

In today's time, agricultural productivity is severely affected by climate change and increasing pollution. Hence, several biotechnological approaches, including genetic and non-genetic strategies, have been developed and adapted to increase agricultural productivity. One of them is nano-priming, i.e., seed priming with nanomaterials. Thus far, nano-priming methods have been successfully used to mount desired physiological responses and productivity attributes in crops. In this review, the literature about the utility of nano-priming methods for increasing seed vigor, germination, photosynthetic output, biomass, early growth, and crop yield has been summarized. Moreover, the available knowledge about the use of nano-priming methods in modulating plant antioxidant defenses and hormonal networks, inducing salinity tolerance and disease resistance, as well as alleviating heavy metal toxicity in plants, is reviewed. The significance of nano-priming methods in the context of phytotoxicity and environmental safety has also been discussed. For future perspectives, knowledge gaps in the present literature are highlighted, and the need for optimization and validation of nano-priming methods and their plant physiological outcomes, from lab to field, is emphasized.

Manganese Oxide Nanoparticles as Safer Seed Priming Agent to Improve Chlorophyll and Antioxidant Profiles in Watermelon Seedlings

The use of nanoscale nutrients in agriculture to improve crop productivity has grown in recent years. However, the bioefficacy, safety, and environmental toxicity of nanoparticles are not fully understood. Herein, we used onion bulb extract to synthesize manganese oxide nanoparticles (MnO-NPs). X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy were used for the structural and morphological characterization of synthesized MnO-NPs. The MnO-NPs were oval shape crystalline nanoparticles of Mn₂O₃ with sizes 22–39 nm. In further studies, we assessed the comparative toxicity of seed priming with MnO-NPs and its bulk counterparts (KMnO₄ and Mn₂O₃), which showed seed priming with MnO-NPs had comparatively less phytotoxicity. Investigating the effect of seed priming with different concentrations of MnO-NPs on the hormonal, phenolic acid, chlorophyll, and antioxidant profiles of watermelon seedlings showed that treatment with 20 mg·L⁻¹ MnO-NPs altered the chlorophyll and antioxidant profiles of seedlings. At ≤40 mg·L⁻¹, MnO-NPs had a remarkable effect on the phenolic acid and phytohormone profiles of the watermelon seedlings. The physiological outcomes of the MnO-NP seed priming in watermelon were genotype-specific and concentration-dependent. In conclusion, the MnO-NPs were safer than their bulk counterparts and could increase crop productivity.

Effects of genotype and production system on quality of tomato fruits and in vitro bile acids binding capacity

Tomato is an important source of health-promoting constituents, and researchers have focused on enhancing the content. In the present study, the influence of net-house (NH) and open-field (OF) growing conditions on physicochemical traits of tomatoes from eight different cultivars were evaluated. The tomato fruit qualities, such as color, total soluble solids (TSS), total acidity (TA), and pH were measured. Furthermore, ultra-performance liquid chromatography coupled to electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry (UPLC/ESI-HR-QTOFMS) was used for identification and quantification of health-promoting compounds such as ascorbic acid, ß-carotene, lycopene, and its isomers. In addition, in vitro bile acid binding capacity of all tomato samples was analyzed along with soluble and insoluble dietary fiber analysis as biofunctional properties. The results suggest that production systems influenced tomato fruit quality and biofunctional characteristics in a variety-specific manner. Notably, TA and all-trans-ß-carotene values were considerably influenced by production systems, and their levels were higher in the NH- and OF-grown tomatoes, respectively. Our findings underline the importance of the rational choice of genotype and production system to obtain high-quality tomatoes with enhanced desired traits for breeders and consumers. PRACTICAL APPLICATION: Tomato is one of the nutritional high-valued horticultural crops. The present study aimed to assess the impact of production systems, such as net-house and open-field conditions, on physicochemical traits and biofunctional properties, in vitro bile acid binding capacity of eight tomato varieties. This study supplies a good reference for the rational selection of genotype and production system to obtain high-quality tomatoes with improved desired traits for breeders and consumers.

Optimizing Secondary Electrospray Ionization High-Resolution Mass Spectrometry (SESI-HRMS) for the Analysis of Volatile Fatty Acids from Gut Microbiome

Gut microbiota plays essential roles in maintaining gut homeostasis. The composition of gut microbes and their metabolites are altered in response to diet and remedial agents such as antibiotics. However, little is known about the effect of antibiotics on the gut microbiota and their volatile metabolites. In this study, we evaluated the impact of a moderate level of ampicillin treatment on volatile fatty acids (VFAs) of gut microbial cultures using an optimized real-time secondary electrospray ionization coupled with high-resolution mass spectrometry (SESI-HRMS). To evaluate the ionization efficiency, different types of electrospray solvents and concentrations of formic acid as an additive (0.01, 0.05, and 0.1%, v/v) were tested using VFAs standard mixture (C2-C7). As a result, the maximum SESI-HRMS signals of all studied m/z values were observed from water with 0.01% formic acid than those from the aqueous methanolic solutions. Optimal temperatures of sample inlet and ion chamber were set at 130 °C and 85 °C, respectively. SESI spray pressure at 0.5 bar generated the maximum intensity than other tested values. The optimized SESI-HRMS was then used for the analysis of VFAs in gut microbial cultures. We detected that the significantly elevated C4 and C7 VFAs in the headspace of gut microbial cultures six hours after ampicillin treatment (1 mg/L). In conclusion, our results suggested that the optimized SESI-HRMS method can be suitable for the analysis of VFAs from gut microbes in a rapid, sensitive, and non-invasive manner.

Production system influences volatile biomarkers in tomato

INTRODUCTION

In recent years, growers have used various production types, including high-tunnel systems, to increase the yield of tomatoes (Lycopersicon esculentum). However, the effect of high-tunnel cultivation, in comparison to conventional open-field production, on aroma and flavor volatiles is not fully understood.

OBJECTIVES

To optimize the extraction and quantification conditions for the analysis of tomato volatiles using headspace solid phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS), and study the effect of production systems on volatile profiles using metabolomics approach.

METHODS

The HS-SPME conditions were optimized for extraction and GC-MS was used to quantify the volatiles from four tomato varieties grown in open-field and high-tunnel systems. Univariate and multivariate analyses were performed to identify the influence of production system on tomato volatiles.

RESULTS AND CONCLUSIONS

The extraction of 2 g tomato samples at 60 °C for 45 min using divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber gave the maximum amounts of volatiles. This optimized method was used to identify and quantify 41 volatiles from four tomato varieties. The levels of β-damascenone were higher in the high-tunnel tomatoes and geranylacetone was higher in open-field tomatoes. These two volatile compounds could be considered as biomarkers for tomatoes grown in high-tunnel and open-field production systems. This study is the first report comparing volatiles in tomatoes grown in high-tunnel and open-field conditions, and our results confirmed that there is a critical need to adopt biomarker-specific production systems to improve the nutritional and organoleptic properties of tomatoes.