Arabidopsis Glutaredoxin S17 Contributes to Vegetative Growth, Mineral Accumulation, and Redox Balance during Iron Deficiency

Abstract

Iron (Fe) is an essential mineral nutrient and a metal cofactor required for many proteins and enzymes involved in the processes of DNA synthesis, respiration, and photosynthesis. Iron limitation can have detrimental effects on plant growth and development. Such effects are mediated, at least in part, through the generation of reactive oxygen species (ROS). Thus, plants have evolved a complex regulatory network to respond to conditions of iron limitations. However, the mechanisms that couple iron deficiency and oxidative stress responses are not fully understood. Here, we report the discovery that an Arabidopsis thaliana monothiol glutaredoxin S17 (AtGRXS17) plays a critical role in the plants ability to respond to iron deficiency stress and maintain redox homeostasis. In a yeast expression assay, AtGRXS17 was able to suppress the iron accumulation in yeast ScGrx3/ScGrx4 mutant cells. Genetic analysis indicated that plants with reduced AtGRXS17 expression were hypersensitive to iron deficiency and showed increased iron concentrations in mature seeds. Disruption of AtGRXS17 caused plant sensitivity to exogenous oxidants and increased ROS production under iron deficiency. Addition of reduced glutathione rescued the growth and alleviates the sensitivity of atgrxs17 mutants to iron deficiency. These findings suggest AtGRXS17 helps integrate redox homeostasis and iron deficiency responses.

Gene Expression Responses to Sequential Nutrient Deficiency Stresses in Soybean

“…PHO1 also plays an important role in mediating the leaf response to -P i conditions [ 37 ]. Also conserved between roots and leaves are: Glyma.06G052000 , a homolog of AtIRT3 , a zinc and Fe transporter [ 38 ]; Glyma.10G231600 , a homolog of AtFRO4 , a ferric reductase regulated by FIT1 [ 39 ]; and Glyma.16G168200 a homolog of AtVIT , a vacuolar Fe transporter responsible for mediating Fe homeostasis [ 40 ]. It is noteworthy that the majority of nutrient stress specific genes are associated with -Fe stress, suggesting that while -Fe stress responses have been well characterized in model species, genes associated with -P i stress remain to be discovered.…”

Biosynthesis of Sulfur-Containing Small Biomolecules in Plants

“…Moreover, GRXS17, a unique Grx family protein characterized by its N-terminal Trx-like domain, interacts with CIA components [61]. Interestingly, GRXS17 is involved in the auxin response during plant development [62,63], as well as in redox regulation in response to iron-deficient conditions [64]. However, a direct interaction between GRXS17 and proteins related to the auxin or iron deficiency response remains unknown [65].…”

Is There a Role for Glutaredoxins and BOLAs in the Perception of the Cellular Iron Status in Plants?

“…In fact, in vitro pull-downs performed using the recombinant protein allowed recovering many non-Fe–S proteins including the NF-YC11 transcriptional regulator (Knuesting et al, 2015). Moreover, there is no variation in the Fe content in mature leaves and only a slight increase in seeds (Yu et al, 2017) of grxs17 plants that exhibit no or minor decreases in the activity of three Fe–S containing enzymes: aconitase, aldehyde oxidase and xanthine dehydrogenase (Knuesting et al, 2015; Iñigo et al, 2016). On the other hand, GRXS17-deficient lines exhibit a slightly increased sensitivity to genotoxic stress which is reminiscent of mutants compromised in the CIA pathway (Iñigo et al, 2016).…”

“…On the other hand, GRXS17-deficient lines exhibit a slightly increased sensitivity to genotoxic stress which is reminiscent of mutants compromised in the CIA pathway (Iñigo et al, 2016). Finally, when GRXS17-deficient lines are exposed to Fe deficiency, the primary root growth reduction, that is already visible under standard conditions, is exacerbated and ROS levels are elevated (Iñigo et al, 2016; Yu et al, 2017). Whether plant GRXS17 and BOLA2 act in concert remains unclear.…”