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

Abstract

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.

Multidimensional Role of Silicon to Activate Resilient Plant Growth and to Mitigate Abiotic Stress

“…The major phytohormones upregulated by Si under abiotic stress conditions include ABA, JA, GA, ET, SA, BR, and IAA ( Arif et al, 2021 ). Si-induced phytohormones synergistically regulate the growth, metabolism, and stress tolerance in pepper, as shown by in silico data analysis ( Gómez-Merino et al, 2020 ). In tobacco and rice, Si regulates gene expression of plant hormones like ABA, JA, SA, and ETH to adjust metabolism against abiotic stress factors ( Table 1 ).…”

Breeding for silicon-use efficiency, protein content and drought tolerance in bread wheat ( Triticum aestivum L.): a review

“…However, breeding methods and genetic control of Si uptake in wheat can be improved by adapting knowledge from other related cereal crops, particularly rice. Reportedly, Si uptake is a polygenic trait and its inheritance is conditioned by many minor genes (Gómez-Merino et al 2020). Also, the expression of Si uptake is highly affected by genotype by environment interactions, suggesting the need for multi-environmental selection of test genotypes to identify varieties that are efficient in Si uptake, and are high yielding and stable candidates for production or breeding.…”

Bismuth Vanadium Oxide Can Promote Growth and Activity in Arabidopsis thaliana

“…Compared with traditional materials, nanomaterials have many advantages and are applied in the information industry, environmental industry, energy ( Zhao et al, 2018 ; Hao et al, 2021 ; Zhao et al, 2021 ) and environmental protection, biological medicine, and other fields ( Castiglione et al, 2011 ). The growth and development of plants are regulated by many factors, such as temperature and hormones ( Brandhoff et al, 2017 ; Ibañez et al, 2017 ; Kim et al, 2017 ; Sun et al, 2019 ; Gómez-Merino et al, 2020 ). An increasing number of studies have shown that nanomaterials also have an impact on the growth and development of plants ( Thuesombat et al, 2014 ).…”