Alteration of iron responsive gene expression in Arabidopsis glutaredoxin S17 loss of function plants with or without iron stress

Authors: CHENG, NINGHUI - Children'S Nutrition Research Center (CNRC); YU, HAN - Children'S Nutrition Research Center (CNRC); RAO, XIAOLAN - University Of North Texas; PARK, SUNGHUN - Kansas State University; CONNOLLY, ERIN - Pennsylvania State University; HIRSCHI, KENDAL - Children'S Nutrition Research Center (CNRC); Nakata, Paul

Submitted to: Plant Signaling and Behavior
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/15/2020
Publication Date: 4/15/2020
Citation: Cheng, N., Yu, H., Rao, X., Park, S., Connolly, E.L., Hirschi, K.D., Nakata, P.A. 2020. Alteration of iron responsive gene expression in Arabidopsis glutaredoxin S17 loss of function plants with or without iron stress. Plant Signaling and Behavior. https://doi.org/10.1080/15592324.2020.1758455.
DOI: https://doi.org/10.1080/15592324.2020.1758455

Interpretive Summary: Iron deficiency is the most common human nutritional disorder in the world. Increasing the available iron concentrations in plant foods would aid efforts to combat this nutritional disorder. Before strategies can be rationally designed to increase available iron concentrations in edible plants we must first gain a better understanding of the mechanisms regulating iron concentrations within the plant. Previously we and other have shown that glutaredoxin proteins such as glutaredoxin S17 (GRXS17) are crucial in regulating iron accumulation in plants. In this study we analyze the expression of iron responsive genes that comprise two different regulatory networks involved in controlling iron uptake and transport within the plant. We analyzed the expression of the iron responsive genes in both GRXS17 knockout and control plants under iron sufficient and deficient growth conditions. Our findings suggest that GRXS17 is required by the plant to tolerate iron deficient growth conditions and plays a negative regulatory role under growth conditions with sufficient iron supply.

Technical Abstract: Iron (Fe) is a mineral nutrient and a metal cofactor essential for plants. Iron limitation can have detrimental effects on plant growth and development, while excess iron inside plant cells leads to oxidative damage. As a result, plants have evolved complex regulatory networks to respond to fluctuations in cellular iron concentrations. The mechanisms that regulate these responses however, are not fully understood. Heterologous expression of an Arabidopsis thaliana monothiol glutaredoxin S17 (GRXS17) suppresses the over-accumulation of iron in the Saccharomyces cerevisiae Grx3/Grx4 mutant and disruption of GRXS17 causes plant sensitivity to exogenous oxidants and iron deficiency stress. GRXS17 may act as an important regulator in the plant's ability to respond to iron deficiency stress and maintain redox homeostasis. Here, we extend this investigation by analyzing iron-responsive gene expression of the Fer-like iron deficiency-induced transcription factor (FIT) network ( FIT , IRT1, FRO1, and FRO2) and the bHLH transcription factor POPEYE (PYE) network (PYE, ZIF1, FRO3, NAS4, and BTS) in GRXS17 KO plants and wildtype controls grown under iron sufficiency and deficiency conditions. Our findings suggest that GRXS17 is required for tolerance to iron deficiency, and plays a negative regulatory role under conditions of iron sufficiency.