Editorial: Ethylene's Role in Plant Mineral Nutrition

Ethylene is a gaseous plant hormone involved in many aspects of plant life, including seed germination, flower senescence, abscission, and fruit ripening (Abeles et al., 1992). It also plays a very important role in the responses of plants to both biotic and abiotic stresses (Abeles et al. The production of ethylene is tightly regulated by internal signals, and usually increases in response to biotic (e.g., pathogen attack) and abiotic stresses, such as mechanical stress, hypoxia, chilling, and nutritional disorders (Abeles et al. In processes related to mineral nutrition, ethylene has been implicated in the regulation of physiological and morphological responses to nutrient deficiencies; in nodulation of legume plants; in salt tolerance responses; and in responses to heavy metals (Abeles et al. This research topic updates recent results relating ethylene to different aspects of plant mineral nutrition. It includes 10 reviews and 2 original articles: 7 reviews are related to nutrient deficiencies 1 to nodulation (Guinel), 1 to salt tolerance (Tao et al.), and 1 to heavy metals (Keunen et al.); 1 original article is related to Fe (iron) deficiency (Ye et al.), and the other one to N (nitrogen) deficiency (De Gernier et al.). The role of ethylene in the regulation of responses to nutrient deficiencies was introduced in the nineties, when some studies showed an implication of ethylene in the regulation of physiological and/or morphological responses to Fe and P (phosphorus) deficiency (Romera and Alcántara, 1994; Lynch and Brown, 1997). In the last years, the role of ethylene has been extended to other nutrient deficiencies, such as K (potassium) deficiency, S (sulfur) deficiency, and others (Iqbal et al., 2013; García et al., 2015). The relationship between ethylene and other processes related to mineral nutrition (nodulation, salinity and heavy metals) has also been known for many years (Abeles et al., 1992; Lynch and Brown, 1997). Since nutrient deficiencies cause stress to plants and stress promotes ethylene synthesis (Abeles et al., 1992), most plant species increase ethylene production under different deficiencies (Lucena et al.; Schachtman; Song and Liu; Wawrzynska et al.). This higher ethylene production is generally associated with increased transcript abundance for genes involved in ethylene biosynthesis and signaling (Lucena et al.; Schachtman; Song and Liu; Wawrzynska et al.; Neumann). Moreover, the mitogen-activated protein kinases 3 and 6 (MPK3/MPK6), that can regulate ethylene production, increase under Fe deficiency (Ye et al.) or under heavy metal stress (Keunen et al.). In …