About this Research Topic
When plants suffer from nutrient deficiency they undergo physiological and morphological changes (mainly in their roots) facilitating the acquisition and mobilization of the limiting nutrient. Examples of physiological responses include acidification of the rhizosphere, release of chelating agents into the medium and enhancement of the uptake capacity.
Examples of morphological responses include changes in root architecture, development of root hairs and formation of transfer cells. The regulation of these responses is not fully understood, but in recent years different plant hormones and signaling substances, such as auxin, ethylene, cytokinins and nitric oxide, have been shown to be involved in their control. Moreover, oxidative stress has also been implicated in the regulation of responses to many nutrient deficiencies.
The relationship between ethylene and the regulation of responses to nutrient deficiencies was introduced in the nineties, when some studies suggested ethylene’s involvement in the regulation of responses to Fe and P deficiency. In the years since, the role of ethylene has been extended to deficiencies of several other nutrients, such as K, Mg, S, N, and others. In most cases, it has been found that ethylene production, as well as the expression of ethylene synthesis genes, increases under these nutrient deficiencies. Furthermore, it has been shown that ethylene controls the expression of genes related to responses to different deficiencies. The involvement of ethylene in so many deficiencies suggests that it acts in conjunction with other signals that confer nutrient-specificity to the distinct deficiency responses. These signals could be other plant hormones or other substances (microRNAs, peptides, glutathione, etc), either originating in the roots or coming from the shoots through the phloem.
The role of ethylene in the mineral nutrition of plants is even more complex than its role in the responses to nutrient deficiencies. Ethylene has been implicated in the N2 fixation of legume plants, in salt tolerance responses and in responses to heavy metals, such as Cd. All these processes are related to ion uptake and, consequently, are related to plant mineral nutrition. We feel this perspective presents a good opportunity to review all the relevant information in a coordinated way.
This Research Topic will provide an overview of the role of the plant hormone ethylene in the regulation of physiological and morphological responses to different nutrient deficiencies. In addition, it will cover other aspects of ethylene related to plant nutrition such as its role in salinity stress, N2 fixation and tolerance to heavy metals. We warmly welcome reviews, mini-reviews and original articles.
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