title: Regulation of Phytosiderophore Release and Antioxidant Defense in Roots Driven by Shoot-Based Auxin Signaling Confers Tolerance to Excess Iron in Wheat.
abstract: Iron (Fe) is essential but harmful for plants at toxic level. However, how wheat plants tolerate excess Fe remains vague. This study aims at elucidating the mechanisms underlying tolerance to excess Fe in wheat. Higher Fe concentration caused morpho-physiological retardation in BR 26 (sensitive) but not in BR 27 (tolerant). Phytosiderophore and 2-deoxymugineic acid showed no changes in BR 27 but significantly increased in BR 26 due to excess Fe. Further, expression ofTaSAMS. TaDMAS1, andTaYSL15significantly downregulated in BR 27 roots, while these were upregulated in BR 26 under excess Fe. It confirms that inhibition of phytosiderophore directs less Fe accumulation in BR 27. However, phytochelatin and expression ofTaPCS1andTaMT1showed no significant induction in response to excess Fe. Furthermore, excess Fe showed increased catalase, peroxidase, and glutathione reductase activities along with glutathione, cysteine, and proline accumulation in roots in BR 27. Interestingly, BR 27 self-grafts and plants having BR 26 rootstock attached to BR 27 scion had no Fe-toxicity induced adverse effect on morphology but showed BR 27 type expressions, confirming that shoot-derived signal triggering Fe-toxicity tolerance in roots. Finally, auxin inhibitor applied with higher Fe concentration caused a significant decline in morpho-physiological parameters along with increasedTaSAMSandTaDMAS1expression in roots of BR 27, revealing the involvement of auxin signaling in response to excess Fe. These findings propose that tolerance to excess Fe in wheat is attributed to the regulation of phytosiderophore limiting Fe acquisition along with increased antioxidant defense in roots driven by shoot-derived auxin signaling.
authors.affiliation: Plant and Crop Physiology Laboratory, Department of Botany, University of Rajshahi Rajshahi, Bangladesh.
authors.forename: Ahmad H
authors.initials: AH
authors.lastname: Kabir
authors.affiliation: Plant and Crop Physiology Laboratory, Department of Botany, University of Rajshahi Rajshahi, Bangladesh.
authors.forename: Most A
authors.initials: MA
authors.lastname: Khatun
authors.affiliation: Plant and Crop Physiology Laboratory, Department of Botany, University of Rajshahi Rajshahi, Bangladesh.
authors.forename: Mohammad M
authors.initials: MM
authors.lastname: Hossain
authors.affiliation: Plant and Crop Physiology Laboratory, Department of Botany, University of Rajshahi Rajshahi, Bangladesh.
authors.forename: Syed A
authors.initials: SA
authors.lastname: Haider
authors.affiliation: Plant and Crop Physiology Laboratory, Department of Botany, University of Rajshahi Rajshahi, Bangladesh.
authors.forename: Mohammad F
authors.initials: MF
authors.lastname: Alam
authors.affiliation: Plant and Crop Physiology Laboratory, Department of Botany, University of Rajshahi Rajshahi, Bangladesh.
authors.forename: Nishit K
authors.initials: NK
authors.lastname: Paul
keywords: 2-DMA; Fe-toxicity; auxin signaling; phytosiderophore release; reciprocal grafting; wheat