Iron homeostasis and plant immune responses: Recent insights and translational implications

Abstract

Iron (Fe) metabolism and the plant immune system are both critical for plant vigor in natural ecosystems and for reliable agricultural productivity. Mechanistic studies of plant iron homeostasis and plant immunity have traditionally been carried out in isolation from each other; however, our growing understanding of both processes has uncovered significant connections. For example, iron plays a critical role in the generation of reactive oxygen intermediates during immunity and has been recently implicated as a critical factor for immune-initiated cell death via ferroptosis. Moreover, plant iron stress triggers immune activation, suggesting that sensing of iron depletion is a mechanism by which plants recognize a pathogen threat. The iron deficiency response engages hormone signaling sectors that are also utilized for plant immune signaling, providing a probable explanation for iron-immunity cross-talk. Finally, interference with iron acquisition by pathogens might be a critical component of the immune response. Efforts to address the global burden of iron deficiency-related anemia, have focused on classical breeding and transgenic approaches to develop crops biofortified for iron content. However, our improved mechanistic understanding of plant iron metabolism suggests that such alterations could promote or impede plant immunity, depending on the nature of the alteration and the virulence strategy of the pathogen. Effects of iron biofortification on disease resistance should be evaluated while developing plants for iron biofortification.

Genome-resolved metagenomics reveals role of iron metabolism in drought-induced rhizosphere microbiome dynamics

“…Collectively, this comparative analysis across small sets of MAGs with differential abundance across drought stress reveals both new and previously identified links between functional categories and drought enrichment status. Interestingly, several recent studies have revealed connections between plant microbiome regulation and inorganic ion transport and metabolism, including those that have identified relationships between phosphate and iron homeostasis and microbiome regulation 29,30 . Additionally, other work has suggested that plant nutrient status may be directly perturbed by drought stress 31 .…”

Iron Availability in Tissue Microenvironment: The Key Role of Ferroportin

“…FPN is also a major player in the iron-immunity crosstalk; interference with iron acquisition by pathogens is a critical component of the immune response and is a widespread mechanism, present also in plants [ 8 ]. Several studies have shown the importance of macrophage FPN in infections, with distinct effects on pathogen growth according to whether microbes are extracellular or intracellular [ 19 , 77 , 78 ].…”

“…The control of iron balance is particularly crucial in the context of infection/inflammation, in which pathogens use multiple mechanisms to acquire iron, whereas the host sequesters iron and starves them of this essential metal. The universality of this response is highlighted by the appreciation that this competition for iron occurs also in plants, as iron sequestration is important for plant immune responses [ 8 ].…”

Soil chemistry determines whether defensive plant secondary metabolites promote or suppress herbivore growth

“…How can soil-and benzoxazinoid-dependent leaf iron homeostasis explain fall armyworm performance? In theory, iron homeostasis may indirectly affect leaf quality by changing leaf primary metabolism and defense expression (36)(37)(38), or directly by acting as a herbivore micronutrient (22). To test the first hypothesis, we measured soluble protein, hydrolysable amino acid and carbohydrate levels in the leaves of WT and bx1 mutant plants grown under different iron regimes (Fig.…”