There is a direct correlation between population growth and food demand. As the global population continues to rise, there is a need to scale up food production to meet the food demand of the population. In addition, the arable land over time has lost its naturally endowed nutrients. Hence, alternative measures such as fertilizers, pesticides, and herbicides are used to fortify the soil and scale up the production rate. As efforts are being made to meet this food demand and ensure food security, it is equally important to ensure food safety for consumption. Food safety measures need to be put in place throughout the food production chain lines. One of the fundamental measures is the use of biofertilizers or plant growth promoters instead of chemical or synthesized fertilizers, pesticides, and herbicides that poise several dangers to human and animal health. Biofertilizers competitively colonize plant root systems, which, in turn, enhance nutrient uptake, increase productivity and crop yield, improve plants’ tolerance to stress and their resistance to pathogens, and improve plant growth through mechanisms such as the mobilization of essential elements, nutrients, and plant growth hormones. Biofertilizers are cost-effective and ecofriendly in nature, and their continuous usage enhances soil fertility. They also increase crop yield by up to about 10–40% by increasing protein contents, essential amino acids, and vitamins, and by nitrogen fixation. This review therefore highlighted different types of biofertilizers and the mechanisms by which they elicit their function to enhance crop yield to meet food demand. In addition, the review also addressed the role of microorganisms in promoting plant growth and the various organisms that are beneficial for enhancing plant growth.

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Salinity stress causes ionic stress (mainly from high Na⁺ and Cl⁻ levels) and osmotic stress (as a result of inhibition of water uptake by roots and amplified water loss from plant tissue), resulting in cell death and inhibition of growth and ultimately adversely reducing crop productivity. In this report, changes in root nitric oxide content, shoot and root biomass, root H₂O₂ content, root lipid peroxidation, root cell death, root caspase-like enzymatic activity, root antioxidant enzymatic activity and root ascorbate and glutathione contents/redox states were investigated in maize (Zea mays L. cv Silverking) after long-term (21 d) salt stress (150 mM NaCl) with or without exogenously applied nitric oxide generated from the nitric oxide donor 2,2'-(Hydroxynitrosohydrazano)bis-ethane. In addition to reduced shoot and root biomass, salt stress increased the nitric oxide and H₂O₂ contents in the maize roots and resulted in elevated lipid peroxidation, caspase-like activity and cell death in the roots. Altered antioxidant enzymatic activities, along with changes in ascorbate and glutathione contents/redox status were observed in the roots in response to salt stress. The detrimental effects of salt stress in the roots were reversed by exogenously applied nitric oxide. These results demonstrate that exogenously applied nitric oxide confers salt stress tolerance in maize by reducing salt stress-induced oxidative stress and caspase-like activity through a process that limits accumulation of reactive oxygen species via enhanced antioxidant enzymatic activity.

Plants are capable of synthesizing all the molecules necessary to complete their life cycle from minerals, water, and light. This plasticity, however, comes at a high energetic cost and therefore plants need to regulate their economy and allocate resources accordingly. Iron–sulfur (Fe–S) clusters are at the center of photosynthesis, respiration, amino acid, and DNA metabolism. Fe–S clusters are extraordinary catalysts, but their main components (Fe2+ and S2−) are highly reactive and potentially toxic. To prevent toxicity, plants have evolved mechanisms to regulate the uptake, storage, and assimilation of Fe and S. Recent advances have been made in understanding the cellular economy of Fe and S metabolism individually, and growing evidence suggests that there is dynamic crosstalk between Fe and S networks. In this review, we summarize and discuss recent literature on Fe sensing, allocation, use efficiency, and, when pertinent, its relationship to S metabolism. Our future perspectives include a discussion about the open questions and challenges ahead and how the plant nutrition field can come together to approach these questions in a cohesive and more efficient way.

The mining of heavy metals from the environment leads to an increase in soil pollution, leading to the uptake of heavy metals into plant tissue. The build-up of toxic metals in plant cells often leads to cellular damage and senescence. Therefore, it is of utmost importance to produce plants with improved tolerance to heavy metals for food security, as well as to limit heavy metal uptake for improved food safety purposes. To achieve this goal, our understanding of the signaling mechanisms which regulate toxic heavy metal uptake and tolerance in plants requires extensive improvement. In this review, we summarize recent literature and data on heavy metal toxicity (oral reference doses) and the impact of the metals on food safety and food security. Furthermore, we discuss some of the key events (reception, transduction, and response) in the heavy metal signaling cascades in the cell wall, plasma membrane, and cytoplasm. Our future perspectives provide an outlook of the exciting advances that will shape the plant heavy metal signaling field in the near future.