Uses, Botanical Characteristics, and Phenological Development of Slender Nightshade (Solanum nigrescens Mart. and Gal.)

Slender nightshade (Solanum nigrescens Mart. and Gal.) is a perennial, herbaceous plant from the Solanaceae family, which is distributed in various environments. The aim of this study was to review the scientific literature and to establish slender nightshade plants under greenhouse conditions in order to record their phenological development. The specialized literature regarding the distribution, botanical characteristics, and uses of such species was analyzed. The phenological development was recorded based on the BBCH (Biologische Bundesanstalt, Bundessortenamt, Chemische Industrie) guide. Slender nightshade seeds were germinated under greenhouse conditions, then transferred to red porous volcano gravel locally known as tezontle in black polyethylene bags and watered with a Steiner nutrient solution. Changes in phenology were monitored and recorded from germination to the ripening of fruit and seeds. Slender nightshade has a wide distribution in Mexico and is used for medicinal and gastronomical purposes, as well as to control pathogens. The phenological development of slender nightshade has seven stages from germination to the ripening of fruit and seeds. Slender nightshade is a poorly studied plant with potential for human consumption. The phenological recording provides a tool for its management and further research as a crop.

Silver Nanoparticles Increase Nitrogen, Phosphorus, and Potassium Concentrations in Leaves and Stimulate Root Length and Number of Roots in Tomato Seedlings in a Hormetic Manner

Background

Silver nanoparticles (AgNPs) display unique biological activities and may serve as novel biostimulators. Nonetheless, their biostimulant effects on germination, early growth, and major nutrient concentrations (N, P, and K) in tomato (Solanum lycopersicum) have been little explored.

Methods

Tomato seeds of the Vengador and Rio Grande cultivars were germinated on filter paper inside plastic containers in the presence of 0, 5, 10, and 20 mg/L AgNPs. Germination parameters were recorded daily, while early growth traits of seedlings were determined 20 days after applying the treatments (dat). To determine nutrient concentrations in leaves, a hydroponic experiment was established, adding AgNPs to the nutrient solution. Thirty-day-old plants were established in the hydroponic system and kept there for 7 days, and subsequently, leaves were harvested and nutrient concentrations were determined.

Results

The AgNPs applied did not affect germination parameters, whereas their application stimulated length and number of roots in a hormetic manner. In 37-day-old plants, low AgNP applications increased the concentrations of N, P, and K in leaves.

Conclusion

As novel biostimulants, AgNPs promoted root development, especially when applied at 5 mg/L. Furthermore, they increased N, P, and K concentration in leaves, which is advantageous for seedling performance during the early developmental stages.

Silicon Stimulates Plant Growth and Metabolism in Rice Plants under Conventional and Osmotic Stress Conditions

Exogenous silicon (Si) can enhance plant resistance to various abiotic factors causing osmotic stress. The objective of this research was to evaluate the application of 1 and 2 mM Si to plants under normal conditions and under osmotic stress. Morelos A-98 rice seedlings, were treated with 1 and 2 mM SiO2 for 28 d. Subsequently, half of the plants were subjected to osmotic stress with the addition of 10% polyethylene glycol (PEG) 8000; and continued with the addition of Si (0, 1 and 2 mM SiO2) for both conditions. The application of Si under both conditions increased chlorophyll b in leaves, root volume, as well as fresh and dry biomass of roots. Interestingly, the number of tillers, shoot fresh and dry biomass, shoot water content, concentration of total chlorophyll, chlorophyll a/b ratio, and the concentration of total sugars and proline in shoot increased with the addition of Si under osmotic stress conditions. The addition of Si under normal conditions decreased the concentration of sugars in the roots, K and Mn in roots, and increased the concentration of Fe and Zn in shoots. Therefore, Si can be used as a potent inorganic biostimulant in rice Morelos A-98 since it stimulates plant growth and modulates the concentration of vital biomolecules and essential nutrients.

Silicon flow from root to shoot in pepper: a comprehensive in silico analysis reveals a potential linkage between gene expression and hormone signaling that stimulates plant growth and metabolism

Background

Silicon (Si) is categorized as a quasi-essential element for plants thanks to the benefits on growth, development and metabolism in a hormetic manner. Si uptake is cooperatively mediated by Lsi1 and Lsi2. Nevertheless, Lsi channels have not yet been identified and characterized in pepper (Capsicum annuum), while genes involved in major physiological processes in pepper are Si-regulated. Furthermore, Si and phytohormones may act together in regulating plant growth, metabolism and tolerance against stress. Our aim was to identify potential synergies between Si and phytohormones stimulating growth and metabolism in pepper, based on in silico data.

Methods

We established a hydroponic system to test the effect of Si (0, 60, 125 and 250 mg L⁻¹ Si) on the concentrations of this element in different pepper plant tissues. We also performed an in silico analysis of putative Lsi genes from pepper and other species, including tomato (Solanum lycopersicum), potato (Solanum tuberosum) and Arabidopsis thaliana, to look for cis-acting elements responsive to phytohormones in their promoter regions. With the Lsi1 and Lsi2 protein sequences from various plant species, we performed a phylogenetic analysis. Taking into consideration the Lsi genes retrieved from tomato, potato and Arabidopsis, an expression profiling analysis in different plant tissues was carried out. Expression of Si-regulated genes was also analyzed in response to phytohormones and different plant tissues and developmental stages in Arabidopsis.

Results

Si concentrations in plant tissues exhibited the following gradient: roots > stems > leaves. We were able to identify 16 Lsi1 and three Lsi2 genes in silico in the pepper genome, while putative Lsi homologs were also found in other plant species. They were mainly expressed in root tissues in the genomes analyzed. Both Lsi and Si-regulated genes displayed cis-acting elements responsive to diverse phytohormones. In Arabidopsis, Si-regulated genes were transcriptionally active in most tissues analyzed, though at different expressed levels. From the set of Si-responsive genes, the NOCS2 gene was highly expressed in germinated seeds, whereas RABH1B, and RBCS-1A, were moderately expressed in developed flowers. All genes analyzed showed responsiveness to phytohormones and phytohormone precursors.

Conclusion

Pepper root cells are capable of absorbing Si, but small amounts of this element are transported to the upper parts of the plant. We could identify putative Si influx (Lsi1) and efflux (Lsi2) channels that potentially participate in the absorption and transport of Si, since they are mainly expressed in roots. Both Lsi and Si-regulated genes exhibit cis-regulatory elements in their promoter regions, which are involved in phytohormone responses, pointing to a potential connection among Si, phytohormones, plant growth, and other vital physiological processes triggered by Si in pepper.

Silicon induces hormetic dose-response effects on growth and concentrations of chlorophylls, amino acids and sugars in pepper plants during the early developmental stage

Background

Silicon (Si) is a beneficial element that has been proven to influence plant responses including growth, development and metabolism in a hormetic manner.

Methods

In the present study, we evaluated the effect of Si on the growth and concentrations of chlorophylls, total amino acids, and total sugars of pepper plants (Capsicum annuum L.) during the early developmental stage in a hydroponic system under conventional (unstressed) conditions. We tested four Si concentrations (applied as calcium silicate): 0, 60, 125 and 250 mg L^-1, and growth variables were measured 7, 14, 21 and 28 days after treatment (dat), while biochemical variables were recorded at the end of the experiment, 28 dat.

Results

The application of 125 mg L^-1 Si improved leaf area, fresh and dry biomass weight in leaves and stems, total soluble sugars, and concentrations of chlorophylls a and b in both leaves and stems. The amino acids concentration in leaves and roots, as well as the stem diameter were the highest in plants treated with 60 mg L^-1 Si. Nevertheless, Si applications reduced root length, stem diameter and total free amino acids in leaves and stems, especially when applied at the highest concentration (i.e., 250 mg L^-1 Si).

Conclusion

The application of Si has positive effects on pepper plants during the early developmental stage, including stimulation of growth, as well as increased concentrations of chlorophylls, total free amino acids and total soluble sugars. In general, most benefits from Si applications were observed in the range of 60-125 mg L^-1 Si, while some negative effects were observed at the highest concentration applied (i.e., 250 mg L^-1 Si). Therefore, pepper is a good candidate crop to benefit from Si application during the early developmental stage under unstressed conditions.

Cerium enhances germination and shoot growth, and alters mineral nutrient concentration in rice

Cerium (Ce) belongs to the rare earth elements (REEs), and although it is not essential for plants, it can stimulate growth and other physiological processes. The objective of this research was to evaluate the effect of Ce on seed germination, initial seedling growth, and vegetative growth in rice (Oryza sativa L.) cv. Morelos A-98. During the germination process, the seeds were treated with Ce concentrations of 0, 4, 8, and 12 μM; after 5 d, germination percentage was recorded and after 10 d seedling growth was measured. For vegetative growth, a hydroponic system was established where 14-d-old plants without previous Ce treatment were transferred into nutrient solution. After two weeks of acclimatizing, 0, 25, 50, and 100 μM Ce were added to the nutrient solution for 28 d. Ce significantly increased germination and the initial growth variables of the seedlings. During vegetative growth, Ce increased plant height, number of tillers, root volume, and shoot fresh and dry biomass, without affecting root biomass weight. With low Ce concentrations (25 and 50 μM), the concentrations of chlorophylls and amino acids in the shoots were similar to those in the control, like amino acid concentration in the roots at a concentration of 25 μM Ce. Conversely, the concentration of total sugars increased in the shoot with the application of 25, 50, and 100 μM Ce, and in the roots with the application of 50 μM Ce. Also, Ce did not affect the concentration of macro or micronutrients in the shoots. However, in the roots, the high Ce concentration decreased the concentrations of Ca, Fe, Mn, and Zn, while the Mg concentration increased. Our results indicate that Ce, at the right concentrations, can function as a biostimulant in rice germination and growth.