Antioxidant and Photosynthetic Responses in Plants Under Boron Toxicity: A Review

Boron (B) is a micronutrient that has long been known essential not only for plants and animals. Otherwise, in crop plants the range of B concentration from essentiality to toxicity appears extremely narrow. Although B deficiency has been well investigated, during recent years many researchers have also investigated boron toxicity effects, making progress in the comprehension of boron transport within plants. Moreover, worldwide B is not uniformed distributed and, especially in arid and semiarid regions, high B concentrations are found in the soil. Boron in plants primarily moves following transpiration stream even though recent evidences have also confirmed the involvement of B transporter and channel (BOR and NIP). In general, the species that tolerate B excess tends to accumulate less B compared to sensitive species. Likewise other abiotic stresses, antioxidants may be involved in the scavenging of Reactive Oxygen Species (ROS) triggered by B toxicity. Photosynthesis parameters in plants grown under high B supply can draw the photosystems situation and the reactions to B toxicity drawing the healthy status of the plants evaluated. Although boron deficiency has been well investigated, during recent years many researchers have also investigated boron toxicity effects, making progress in the comprehension of boron transport within plants. This review represents the actual state of knowledge concerning B toxicity.