Effects of Magnesium Oxide and Magnesium Hydroxide Microparticle Foliar Treatment on Tomato PR Gene Expression and Leaf Microbiome

Abstract

Recently, metal oxides and magnesium hydroxide nanoparticles (NPs) with high surface-to-volume ratios were shown to possess antibacterial properties with applications in biomedicine and agriculture. To assess recent observations from field trials on tomatoes showing resistance to pathogen attacks, porous micron-scale particles composed of nano-grains of MgO were hydrated and sprayed on the leaves of healthy tomato (Solanum lycopersicum) plants in a 20-day program. The results showed that the spray induced (a) a modest and selective stress gene response that was consistent with the absence of phytotoxicity and the production of salicylic acid as a signalling response to pathogens; (b) a shift of the phylloplane microbiota from near 100% dominance by Gram (−) bacteria, leaving extremophiles and cyanobacteria to cover the void; and (c) a response of the fungal leaf phylloplane that showed that the leaf epiphytome was unchanged but the fungal load was reduced by about 70%. The direct microbiome changes together with the low level priming of the plant’s immune system may explain the previously observed resistance to pathogen assaults in field tomato plants sprayed with the same hydrated porous micron-scale particles.

The power of magnesium: unlocking the potential for increased yield, quality, and stress tolerance of horticultural crops

“…Furthermore, Mg 2+ influences gene expression by modulating multiple phases of transcription and RNA processing. It activates and regulates enzymes and proteins essential for DNA replication, transcription, and RNA maturation, such as DNA and RNA polymerases ( Adhikari et al., 2006 ; Andreadelli et al., 2021 ; El-Sharkawy et al., 2022 ). By interacting with various enzymes involved in DNA repair, Mg 2+ enhances their activity and ensures the effective transcription of genetic information.…”

“…Mg 2+ is a critical element that permeates various cellular functions within plants, acts as a catalyst in enzymatic reactions, stabilizes cell membranes, and contributes to ion homeostasis ( Farhat et al., 2016 ; Tian et al., 2022 ). Its diverse roles are essential for the optimal growth, development, and productivity of horticultural crops ( Andreadelli et al., 2021 ). Recognizing the paramount importance of Mg 2+ in plants, the following sections will delve into the multifaceted roles of Mg 2+ , exploring how it orchestrates and supports essential cellular functions, from energy metabolism to structural stability and resilience.…”

“…It has a symbiotic relationship with the cell wall, fortifying plant cells against pathogen infiltration, while ensuring the optimal function of defense-signaling proteins ( Ye et al., 2021 ; Hamedeh et al., 2022 ). Within this cellular symphony, Mg 2+ guarantees the stability of RNA and the timely synthesis of defense-related proteins in the face of pathogenic threats, a response greatly amplified by its availability ( Liang et al., 2017 ; Andreadelli et al., 2021 ). Additionally, as a co-factor for an array of enzymes, Mg 2+ oversees reactive oxygen species detoxification and the synthesis of defence compounds, forming an immediate shield against biotic stressors ( Faizan et al., 2022 ).…”

“…Their findings are particularly timely given the increasing global challenges posed by Cu-tolerant pathogens in agriculture. Andreadelli et al (2021) highlighted that hydrated MgO NPs sprays resulted in a profound alteration of the tomato phylloplane microbiota. This modification strengthens their immune systems, leading to a 70% reduction in fungal infestation.…”

Influence of biosynthesized magnesium oxide nanoparticles on growth and physiological aspects of cowpea (Vigna unguiculata L.) plant, cowpea beetle, and cytotoxicity

“…MgONPs have been demonstrated to be antibacterial agents among inorganic metal oxides, with the added benefits of being non‐toxic, non‐bioaccumulative, and non‐persistent. While the “US Food and Drug Administration” considers MgO and Mg(OH) 2 to be safe, [ 32 ] and the “European Chemical Agency” has found that Mg(OH) 2 is neither persistent, bio‐accumulative, or poisonous, the NP form of these minerals is not mentioned directly. In this work, we attempted to investigate a quick, cost‐effective, and environmentally friendly technique for producing MgONPs utilizing S. cerevisiae extract.…”