Root hairs on chlorotic tomatoes are an effect of chlorosis rather than part of the adaptive Fe‐stress‐response

Chaney, Rufus L.; Chen, Y.; Green, C. E.; Holden, Marcia J.; Bell, Paul F.; Luster, Douglas G.; Angle, J. S.

doi:10.1080/01904169209364444

Cited by 45 publications

(20 citation statements)

References 26 publications

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“…In contrast, in A. thaliana, increased root hair formation was seen after 24 h of iron deficiency, before chlorosis occurred. This time sequence of stress responses is in agreement with an earlier report (Bell et al 1988) on the same tomato cultivar as used in the study of Chaney et al (1992).…”

Section: Discussionsupporting

confidence: 87%

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Responses to iron deficiency in Arabidopsis thaliana: The Turbo iron reductase does not depend on the formation of root hairs and transfer cells

Moog

Kooij

Brüggemann

et al. 1995

Planta

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Arabidopsis thaliana (L.) Heynh. Columbia wild type and a root hair-less mutant RM57 were grown on iron-containing and iron-deficient nutrient solutions. In both genotypes, ferric chelate reductase (FCR) of intact roots was induced upon iron deficiency and followed a Michaelis-Menten kinetic with a Km of 45 and 54 microM FeIII-EDTA and a Vmax of 42 and 33 nmol Fe2+.(g FW)-1.min-1 for the wild type and the mutant, respectively. The pH optimum for the reaction was around pH 5.5. The approximately four fold stimulation of FCR activity was independent of formation of root hairs and/or transfer cells induced by iron deficiency. Iron-deficiency-induced chlorosis and the development of a rigid root habit disappeared when ferric chelate was applied to the leaves, while FCR activity remained unchanged. The time course of the responses to iron deficiency showed that morphological and physiological responses were controlled separately.

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Section: Discussionsupporting

confidence: 87%

“…In iron-deficient tomatoes, Chaney et al (1992) observed increased root hair formation only after 5 d of iron deficiency, when severe chlorosis was already established. In contrast, in A. thaliana, increased root hair formation was seen after 24 h of iron deficiency, before chlorosis occurred.…”

Section: Discussionmentioning

confidence: 84%

Responses to iron deficiency in Arabidopsis thaliana: The Turbo iron reductase does not depend on the formation of root hairs and transfer cells

Moog

Kooij

Brüggemann

et al. 1995

Planta

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“…In Arabidopsis split roots, root hairs develop in the ϪFe-grown side, but not in the ϩFe-grown side. This morphological adaptation, but not the induction of ferric reductase activity, is impaired in ethylene mutants (Schikora and Schmidt, 2001), indicating that the two responses to iron deficiency are regulated in a different manner, as already suggested (Chaney et al, 1992;Moog et al, 1995). The fact that both expression of IRT1 and FRO2 and the iron deficiency-induced root hair formation respond to local iron levels indicates the requirement for an iron sensor in the root.…”

Section: Discussionmentioning

confidence: 84%

Dual Regulation of the Arabidopsis High-Affinity Root Iron Uptake System by Local and Long-Distance Signals

2003

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Regulation of the root high-affinity iron uptake system by whole-plant signals was investigated at the molecular level in Arabidopsis, through monitoring FRO2 and IRT1 gene expression. These two genes encode the root ferric-chelate reductase and the high-affinity iron transporter, respectively, involved in the iron deficiency-induced uptake system. Recovery from iron-deficient conditions and modulation of apoplastic iron pools indicate that iron itself plays a major role in the regulation of root iron deficiency responses at the mRNA and protein levels. Split-root experiments show that the expression of IRT1 and FRO2 is controlled both by a local induction from the root iron pool and through a systemic pathway involving a shoot-borne signal, both signals being integrated to tightly control production of the root iron uptake proteins. We also show that IRT1 and FRO2 are expressed during the day and down-regulated at night and that this additional control is overruled by iron starvation, indicating that the nutritional status prevails on the diurnal regulation. Our work suggests, for the first time to our knowledge, that like in grasses, the root iron acquisition in strategy I plants may also be under diurnal regulation. On the basis of the new molecular insights provided in this study and given the strict coregulation of IRT1 and FRO2 observed, we present a model of local and long-distance regulation of the root iron uptake system in Arabidopsis.Iron is an essential element for all living organisms, including plants. As a transition metal, its ability to gain and lose an electron confers iron important properties for redox reactions. Although abundant in soils, iron often forms highly insoluble ferrichydroxide precipitates that limit its availability for plants (Guerinot and Yi, 1994). Therefore, mechanisms allowing plants to solubilize and to efficiently take up iron have evolved. However, those mechanisms are carefully regulated to prevent oxidative damages due to iron overload. Angiosperms can be divided into two groups based on their strategies of iron uptake. Non-graminaceous strategy I plants rely on acidification of the rhizosphere to increase solubility of ferric iron complexes through activation of an H ϩ -ATPase activity, transplasma membrane electron transfer to reduce iron into its more soluble ferrous form, and a transport activity to provide iron to root cells (Marschner et al., 1986). Grasses, also called strategy II plants, respond to iron insufficiency by releasing phytosiderophores, which have a strong affinity for ferric iron, and by transporting the Fe(III)-phytosiderophore complex across the plasma membrane of the root epidermal cell (Takagi et al., 1984).A great effort has recently been made to isolate genes involved in this root response to iron deficiency, especially in Arabidopsis. In this species, the acidification function is likely to be performed by a member of the H ϩ -ATPase AHA family (Palmgren, 2001), whereas the root ferric reductase that reduces ferric iron into ferrous iron in ...

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“…The reduction rate of Fe3' from rhizoferrin did not significantly differ from that measured on control plants that were not supplied with Fe during the reduction experiment (Table 111). In general, the reduction rates measured were about 17-to 54-fold lower than that commonly found in Fe-deficient dicots (Romheld and - Kramer, 1983;Romheld and Marschner, 1983;Chaney et al, 1992). Measurements of Fe reduction by roots that were not supplied with Fe-chelate indicate that the low reduction rate measured was actually from the precipitated Fehydroxides on the roots, rather than from the chelated Fe3+.…”

Section: Fe3+ Reduction By Corn Plantsmentioning

confidence: 75%

The Role of Ligand Exchange in the Uptake of Iron from Microbial Siderophores by Gramineous Plants

et al. 1996

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Root hairs on chlorotic tomatoes are an effect of chlorosis rather than part of the adaptive Fe‐stress‐response

Cited by 45 publications

References 26 publications

Responses to iron deficiency in Arabidopsis thaliana: The Turbo iron reductase does not depend on the formation of root hairs and transfer cells

Responses to iron deficiency in Arabidopsis thaliana: The Turbo iron reductase does not depend on the formation of root hairs and transfer cells

Dual Regulation of the Arabidopsis High-Affinity Root Iron Uptake System by Local and Long-Distance Signals

The Role of Ligand Exchange in the Uptake of Iron from Microbial Siderophores by Gramineous Plants

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