Physiological Responses to Fe Deficiency in Split-Root Tomato Plants: Possible Roles of Auxin and Ethylene?

Abstract

Iron (Fe) bioavailability in soils is often limited and can be further exacerbated by a non- homogeneous distribution in the soil profile, which has been demonstrated to vary both in space and time. Consequently, plants respond with morphological and physiological modifications at the root level involving a complex local and systemic signaling machinery. The present work unravels the role of two phytohormones (i.e., ethylene and auxin) and their integrated signaling in plant response to Fe deficiency. Inhibitors of auxin polar transport and of ethylene biosynthesis (N-1-naphthylphthalamic acid - NPA and aminoethoxyvinylglycine - AVG, respectively) were applied on tomato (Solanum lycopersicum L.) plants grown by the split-root technique, which allows to simulate condition of Fe heterogeneous distribution. Results showed that plants, exposed to an uneven Fe supply, triggered a complex auxin-ethylene signaling. A systemic action of auxin on FERRIC REDUCTASE OXIDASE 1 (SlFRO1) expression was revealed, while ethylene signaling was effective both locally and systemically. In addition, the investigation of Fe concentration in tissues showed that when leaves overcame Fe deficiency a Fe “steady state” was maintained. Therefore, physiological adaptation to this heterogeneous Fe supply could be mediated by the integration of the complex signaling pathways prompted by both auxin and ethylene activities.

Evaluation of total protein, peroxidase, and nutrients measured by pXRF for the determination of tissue rejuvenation/reinvigoration of Eucalyptus microcorys

“…With Fe, only the E. microcorys selected tree did not have adequate Fe levels. Iron is related to enzyme biosynthesis linked to peroxidase pathways, which are directly involved in cell growth and expansion, root differentiation and development, and auxin catabolism and lignification (Lima et al 2018;Celletti et al 2020). In this study, there was no similarity detected between peroxidase activity and Fe contents in individuals, especially when analyzing the adventitious rooting of mini cuttings.…”

The activation of iron deficiency responses of grapevine rootstocks is dependent to the availability of the nitrogen forms

“…Similar results were obtained by [ 106 ] in the case of citrus rootstocks grown under natural Fe-deficiency conditions, which appear to be associated with general responses to Fe deficiency, most likely by preventing the negative effects of reactive oxygen species damages [ 107 ]. In contrast, several genes involved in phytohormones pathways were significantly down-regulated in the auxin metabolic pathway in Fercal and in the ethylene signalling pathway in 3309 C. These two phytohormones have been widely demonstrated to be involved in regulating the responses to Fe deficiency by stimulating plant root growth and increasing the expression of genes involved in Fe acquisition in Strategy I plants [ 108 , 109 ].…”

A genome‐wide association study identifies novel players in Na and Fe homeostasis in Arabidopsis thaliana under alkaline‐salinity stress

“…Physical interaction between AtALA3 and two ARFGEFs (ADPribosylation factor GTPases) ‐ BIG3 (Brefeldin A‐Inhibited Guanine Nucleotide‐Exchange Protein3) and GNOM, which is essential for proper trafficking of PIN auxin transporters – has been observed in endomembrane, thus regulating trafficking events in the late secretory pathway and ala3 mutants are defective in auxin mediated developmental processes (Zhang et al., 2020 ). There is increasing evidence for a role of auxin in plant response to both the Fe deficiency (Celletti et al., 2020 ) and salinity (Cackett et al., 2022 ). Plant P4 ATPases are expected to have a major role in any physiological process involving lipid signaling, vesicle formation and/or lipid‐dependent protein recruitment to membranes.…”