Alleviation of boron toxicity in plants: Mechanisms and approaches

Boron (B) is an essential element for higher plants, while it becomes toxic when present in excessive concentrations. Many approaches have been developed to alleviate B toxicity in plants. This paper summarizes the recent advances in the mechanisms and related approaches for B toxicity alleviation, discusses the limitations of different approaches, and proposes suggestions for future studies. The alleviative approaches have been briefly outlined as three mechanisms. The first is the decrease in tissue B concentration, including the decrease in soil available B and the restriction on B uptake. The second is the decrease in cellular active B, including the formation of inert complexes and the regulation of B translocation. The third is the increase in physiological tolerance, including the prevention of oxidative damages, the enhancement of photosynthesis, the improvement of plant water status, and the screening of B-tolerant genotypes or rootstocks. The alleviative approaches mainly include the application of nutrient elements, plant growth regulators, and plant growth-promoting microbes. Leaching B out of the topsoil and washing B off the plant leaf using water are also included. Future perspectives regarding more practical approaches for B toxicity alleviation and a better understanding of related mechanisms have been proposed.