Understanding the Mechanisms of Fe Deficiency in the Rhizosphere to Promote Plant Resilience

Abstract

One of the most significant constraints on agricultural productivity is the low availability of iron (Fe) in soil, which is directly related to biological, physical, and chemical activities in the rhizosphere. The rhizosphere has a high iron requirement due to plant absorption and microorganism density. Plant roots and microbes in the rhizosphere play a significant role in promoting plant iron (Fe) uptake, which impacts plant development and physiology by influencing nutritional, biochemical, and soil components. The concentration of iron accessible to these live organisms in most cultivated soil is quite low due to its solubility being limited by stable oxyhydroxide, hydroxide, and oxides. The dissolution and solubility rates of iron are also significantly affected by soil pH, microbial population, organic matter content, redox processes, and particle size of the soil. In Fe-limiting situations, plants and soil microbes have used active strategies such as acidification, chelation, and reduction, which have an important role to play in enhancing soil iron availability to plants. In response to iron deficiency, plant and soil organisms produce organic (carbohydrates, amino acids, organic acids, phytosiderophores, microbial siderophores, and phenolics) and inorganic (protons) chemicals in the rhizosphere to improve the solubility of poorly accessible Fe pools. The investigation of iron-mediated associations among plants and microorganisms influences plant development and health, providing a distinctive prospect to further our understanding of rhizosphere ecology and iron dynamics. This review clarifies current knowledge of the intricate dynamics of iron with the end goal of presenting an overview of the rhizosphere mechanisms that are involved in the uptake of iron by plants and microorganisms.

The activation of iron deficiency responses of grapevine rootstocks is dependent to the availability of the nitrogen forms

“…Our results provide some additional information to explain the different genotype response to Fe deficiency, which seems to be a combination of intrinsic factors of gene regulation and environmental influences, such as the form of available N. The pH of the nutrient solution was strongly influenced by the form of N in the nutrient solution, as the presence of ammonium reduced the pH values (more acidic), while nitrate slightly increased the pH value, this effect has already been observed in previous studies [ 74 , 75 ]. The rhizosphere acidification is a well-known mechanism to enhance the availability of some nutrients, especially of Fe [ 76 ]. Nitrate-fed plants seems to suffered more from Fe deficiency exhibiting severe symptoms, low total chlorophyll contents, and low efficiency of photosystem II (FvFm).…”

Exploring the Role of Debaryomyces hansenii as Biofertilizer in Iron-Deficient Environments to Enhance Plant Nutrition and Crop Production Sustainability

“…Among the nutrient disorders in plants, iron (Fe) deficiency represents a prominent agricultural issue all over the world [ 42 , 43 ]. Despite being the fourth most abundant element in the Earth’s crust, Fe primarily exists in its oxidized form as Fe 3+ , with poor solubility under the basic pH conditions commonly found in calcareous soils [ 44 ]. Plant classification, based on their strategies for Fe acquisition from the soil, has divided them into two categories: Strategy I, which is employed by all higher plants except grasses, and Strategy II, exclusive to grasses [ 45 ].…”

Trichoderma afroharzianumT22 induces rhizobia and flavonoid-driven symbiosis to promote iron deficiency tolerance in garden pea

“…Plants employing strategy I typically possess ferric chelate reductase activity, converting Fe(III) to readily available Fe(II) for plants (Kabir et al 2012). The acidification of the rhizosphere via H + secretion is another important method plants utilize to solubilize soil Fe (Molnár et al 2023;Kabir et al 2012). In addition, phenolic compounds, released through root exudates, exhibit chelating and reducing actions in response to Fe shortage in plants (Curie and Mari 2017;Rodríguez-Celma and Schmidt 2013).…”