On the role of iodine in plants: a commentary on benefits of this element

Abstract

Iodine (I) is one of the least abundant elements on Earth’s surface; soils have only about 3 mg kg–1 of total I (Mohiuddin et al., 2019). However, this value can be higher in places close to the coast and lower in areas with slight marine influence (Fuge and Johnson, 2015). The marine environment is rich in this element, having about 60 μg L–1 and being the largest I reservoir on the planet (Wong, 1991). Regarding availability of I in soils, a small amount of it is present in the soil solution, with the major fraction being associated with the solid phase, i.e., organic matter and clay minerals, as well as iron (Fe) and aluminum (Al) oxides (Fuge and Johnson, 1986). Some substrate characteristics, such as mineral/organic composition, pH, texture, and redox conditions, limit I mobility and, thus, its absorption by plants (Gonzali et al., 2017). Consequently, knowing the distribution of I worldwide is key for a better understanding of its importance in living beings, from microorganisms to humans, and in plants.