Arabidopsis Monothiol Glutaredoxin, AtGRXS17, Is Critical for Temperature-dependent Postembryonic Growth and Development via Modulating Auxin Response

Abstract

Global environmental temperature changes threaten innumerable plant species. Although various signaling networks regulate plant responses to temperature fluctuations, the mechanisms unifying these diverse processes are largely unknown. Here, we demonstrate that an Arabidopsis monothiol glutaredoxin, AtGRXS17 (At4g04950), plays a critical role in redox homeostasis and hormone perception to mediate temperature-dependent postembryonic growth. AtGRXS17 expression was induced by elevated temperatures. Lines altered in AtGRXS17 expression were hypersensitive to elevated temperatures and phenocopied mutants altered in the perception of the phytohormone auxin. We show that auxin sensitivity and polar auxin transport were perturbed in these mutants, whereas auxin biosynthesis was not altered. In addition, atgrxs17 plants displayed phenotypes consistent with defects in proliferation and/or cell cycle control while accumulating higher levels of reactive oxygen species and cellular membrane damage under high temperature. Together, our findings provide a nexus between reactive oxygen species homeostasis, auxin signaling, and temperature responses.

Glutaredoxin GRXS17 Associates with the Cytosolic Iron-Sulfur Cluster Assembly Pathway

“…Many of the genes in this network are known to be induced upon genotoxic stress (Ascencio-Ibáñez et al, 2008). Because Arabidopsis mutant plants compromised in components of the purified CIA complex (Table I), namely AE7/ CIA2 (Luo et al, 2012) and MET18/MMS19 (Han et al, 2015), have been reported to have increased expression of DNA-damage response genes (Luo et al, 2012;Han et al, 2015), we analyzed the expression of POLY(ADP-RIBOSE) POLYMERASE2 (PARP2), a frequently used marker gene, in the grxs17-1 mutant, as well as in an antisense line, denominated grxs17-2, that was previously described (Cheng et al, 2011) and which we confirmed to lack GRXS17 protein accumulation (Supplemental Fig. S2C).…”

“…A transfer DNA (T-DNA) insertion line (grxs17-1; SALK_021301) described previously (Supplemental Fig. S1; Cheng et al, 2011;Knuesting et al, 2015) was characterized in detail and found to lack both GRXS17 transcripts (Supplemental Fig. S2B) and GRXS17 protein (Supplemental Fig.…”

“…Its physiological and molecular role in plants is not well understood (Couturier et al, 2013). GRXS17 function has been associated with protection against oxidative stress in Arabidopsis and thermotolerance in Arabidopsis and tomato (Cheng et al, 2011;Wu et al, 2012;Knuesting et al, 2015). Arabidopsis GRXS17 loss-of-function plants (grxs17) are hypersensitive to heat stress and show alterations in auxin sensitivity and polar transport (Cheng et al, 2011).…”

“…GRXS17 function has been associated with protection against oxidative stress in Arabidopsis and thermotolerance in Arabidopsis and tomato (Cheng et al, 2011;Wu et al, 2012;Knuesting et al, 2015). Arabidopsis GRXS17 loss-of-function plants (grxs17) are hypersensitive to heat stress and show alterations in auxin sensitivity and polar transport (Cheng et al, 2011). The molecular function of an association of cytosolic monothiol GRX with Fe-S clusters and the CIA pathway has been a subject of debate, and a role in Fe, Fe-S, or oxidative signaling has been proposed, in addition to a role in delivery or repair of Fe-S clusters (Couturier et al, 2015).…”

Glutathione – linking cell proliferation to oxidative stress

“…The grxs17 mutants exhibit decreased polar auxin transport and they have a weaker auxin response, as well as showing a temperature-dependent inhibition of root growth and agravitropism (55).…”