Boron supply alleviates cadmium toxicity in rice (Oryza sativa L.) by enhancing cadmium adsorption on cell wall and triggering antioxidant defense system in roots.

Cadmium (Cd) pollution is a key concern globally that affects plant growth and productivity. Boron (B) is a micronutrient that helps in the formation of the primary cell wall (CW) and alleviates negative effects of toxic elements on plant growth. Nonetheless, knowledge about how B can reduce Cd toxicity in rice seedlings is not enough, particularly regarding CW-Cd adsorption. Therefore, the current experiment investigated the alleviative role of B on Cd toxicity in rice seedling. The experiment was carried out with 0 μM and 30 μM HBO under 50 μM Cd toxicity in hydroponics. The results showed that Cd exposure alone inhibited plant growth parameters and caused lipid peroxidation. Moreover, Cd toxicity led to obvious visible toxicity symptoms on the leaves. However, increasing the availability of B alleviated Cd toxicity by reducing Cd concentration in plant tissues and improving antioxidative system. Moreover, cell wall pectin and hemicellulose adsorbed a significant amount of Cd. Fourier-Transform Infrared spectroscopy (FTIR) spectra exhibited that cell wall functional groups were increased by B application. Scanning electron microscopy (SEM) equipped with energy-dispersive X-ray (EDX) microanalysis confirmed the higher Cd binding onto CW. The findings of this investigation showed that B could mitigate Cd stress by decreasing Cd uptake and encouraging Cd adsorption on CW, and activation of the protective mechanisms. The present results might help to increase rice productivity on Cd polluted soils.