Regulation of plants nutrient deficiency responses by phytohormones

Abstract

Living organisms have the ability to acquire nutrients from their physical environment and subsequently convert them into an energy source for survival and growth. In plants, nutrients are involved in metabolism and physiology either as constituents of metabolites or enzymes for macromolecule biosynthesis. Based on their concentration in plant dry matter, the 14 essential inorganic elements are categorized into macronutrients and micronutrients. Macronutrients include six elements, nitrogen (N), phosphorus (P), potassium (K), sulfur (S), calcium (Ca), and magnesium (Mg), whereas the micronutrients comprised eight elements, chlorine (Cl), iron (Fe), boron (B), manganese (Mn), zinc (Zn), copper (Cu), molybdenum (Mo), and nickel (Ni) (de Bang et al., 2020; Sustr et al., 2019). Nutrients are distributed in a patchy manner in soil due to their variable interactions with spatially and temporally dispersed charged soil particles (Hodge, 2006). This, along with many other factors, leads to either low nutrient concentration in soil or low accessibility for plants. Low availability of a nutrient causes specific deficiency symptoms. But plants usually face multiple nutrient deficiencies simultaneously leading to a complex response and symptoms. Moreover, various biotic and abiotic stress factors, such as pests, pathogens, water deficit, salinity, and light, also interact to cause atypical nutrient deficiency symptoms (Amtmann et al., 2008; Troufflard et al., 2010; Atkinsonand Urwin., 2012). Globally, nutrient deficiencies are major threats to crop production, causing reduced yields and poor food and feed quality. The world food security challenge is being met by the use of chemical fertilizers (natural and anthropogenic).