Regulation of the iron-deficiency response by IMA/FEP peptide

Transcription factors dealing with Iron-deficiency stress in plants: focus on the bHLH transcription factor family

Iron (Fe), as an important micronutrient element necessary for plant growth and development, not only participates in multiple physiological and biochemical reactions in cells but also exerts a crucial role in respiration and photosynthetic electron transport. Since Fe is mainly present in the soil in the form of iron hydroxide, Fe deficiency exists universally in plants and has become an important factor triggering crop yield reduction and quality decline. It has been shown that transcription factors (TFs), as an important part of plant signaling pathways, not only coordinate the internal signals of different interaction partners during plant development, but also participate in plant responses to biological and abiotic stresses, such as Fe deficiency stress. Here, the role of bHLH transcription factors in the regulation of Fe homeostasis (mainly Fe uptake) is discussed with emphasis on the functions of MYB, WRKY and other TFs in the maintenance of Fe homeostasis. This review provides a theoretical basis for further studies on the regulation of TFs in Fe deficiency stress response.

IMA peptides function in iron homeostasis and cadmium resistance

Iron (Fe), an essential micronutrient, participates in photosynthesis, respiration, and many other enzymatic reactions. Cadmium (Cd), by contrast, is a toxic element to virtually all living organisms. Both Fe deficiency and Cd toxicity severally impair crop growth and productivity, finally leading to human health issues. Understanding how plants control the uptake and homeostasis of Fe and combat Cd toxicity thus is mandatory to develop Fe-enriched but Cd-cleaned germplasms for human beings. Recent studies in Arabidopsis and rice have revealed that IRON MAN (IMA) peptides stand out as a key regulator to respond to Fe deficiency by competitively interacting with a ubiquitin E3 ligase, thus inhibiting the degradation of IVc subgroup bHLH transcription factors (TFs), mediated by 26 S proteasome. Elevated expression of IMA confers tolerance to Cd stress in both Arabidopsis and wheat by activating the iron deficiency response. Here, we discuss recent breakthroughs that IMA peptides function in the Fe-deficiency response to attain Fe homeostasis and combat Cd toxicity as a potential candidate for phytoremediation.