Lucena Carlos, Romera Francisco J, García María J, Alcántara Esteban, Pérez-Vicente Rafael
Department of Agronomy, University of Córdoba Córdoba, Spain.
Department of Botany, Ecology and Plant Physiology, University of Córdoba Córdoba, Spain.
Front Plant Sci. 2015 Nov 27;6:1056. doi: 10.3389/fpls.2015.01056. eCollection 2015.
Iron (Fe) is very abundant in most soils but its availability for plants is low, especially in calcareous soils. Plants have been divided into Strategy I and Strategy II species to acquire Fe from soils. Strategy I species apply a reduction-based uptake system which includes all higher plants except the Poaceae. Strategy II species apply a chelation-based uptake system which includes the Poaceae. To cope with Fe deficiency both type of species activate several Fe deficiency responses, mainly in their roots. These responses need to be tightly regulated to avoid Fe toxicity and to conserve energy. Their regulation is not totally understood but some hormones and signaling substances have been implicated. Several years ago it was suggested that ethylene could participate in the regulation of Fe deficiency responses in Strategy I species. In Strategy II species, the role of hormones and signaling substances has been less studied. However, in rice, traditionally considered a Strategy II species but that possesses some characteristics of Strategy I species, it has been recently shown that ethylene can also play a role in the regulation of some of its Fe deficiency responses. Here, we will review and discuss the data supporting a role for ethylene in the regulation of Fe deficiency responses in both Strategy I species and rice. In addition, we will review the data about ethylene and Fe responses related to Strategy II species. We will also discuss the results supporting the action of ethylene through different transduction pathways and its interaction with other signals, such as certain Fe-related repressive signals occurring in the phloem sap. Finally, the possible implication of ethylene in the interactions among Fe deficiency responses and the responses to other nutrient deficiencies in the plant will be addressed.
铁（Fe）在大多数土壤中含量非常丰富，但植物对其利用率较低，尤其是在石灰性土壤中。植物已被分为策略I型和策略II型物种，以便从土壤中获取铁。策略I型物种采用基于还原的吸收系统，包括除禾本科植物外的所有高等植物。策略II型物种采用基于螯合的吸收系统，包括禾本科植物。为了应对缺铁，这两种类型的物种都会激活几种缺铁反应，主要发生在它们的根部。这些反应需要严格调控，以避免铁毒性并节约能量。其调控机制尚未完全了解，但一些激素和信号物质已被牵涉其中。几年前有人提出，乙烯可能参与策略I型物种缺铁反应的调控。在策略II型物种中，激素和信号物质的作用研究较少。然而，在传统上被认为是策略II型物种但具有一些策略I型物种特征的水稻中，最近发现乙烯也可以在其一些缺铁反应的调控中发挥作用。在这里，我们将回顾和讨论支持乙烯在策略I型物种和水稻缺铁反应调控中起作用的数据。此外，我们将回顾与策略II型物种相关的乙烯和铁反应的数据。我们还将讨论支持乙烯通过不同转导途径发挥作用及其与其他信号相互作用的结果，例如韧皮部汁液中出现的某些与铁相关的抑制信号。最后，将探讨乙烯在植物缺铁反应与对其他养分缺乏反应之间相互作用中的可能影响。
