Low antimony concentration promoted growth, glucosinolates metabolism and biological activity of two Brassica sp.

Abstract Antimony (Sb), a common rare heavy metal, found naturally in soils at low conecntrations. Thus, this study aimed to understand how plants cope with the low Sb concentrations. To this end, Brassica napus and Brassica rapa were treated with Sb at 8 mg/kg soil to explore their responses on the levels of growth, photosynthesis, glucosinolates metabolism, redox status and and biological activity. Our results revealed that Sb significantly promoted growth by 1.34 and 1.14-fold in B. napus and B. rapa compared to control conditions. This increase can be explained by the observed increase in photosynthesis as indicated by increased chlorophyll content. Sb significantly improved total glucosinolates accumulation, possibly through improved amino acids production, namely, alanine, leucine, isoleucine, valine, methionine, phenylalanine, tyrosine, and tryptophan. There were increases in myrosinase activity, which stimulated glucosinolates hydrolysis to yield health-promoting sulforaphane. In contrast, low level of ineffective sulforaphane nitrile was detected. Sb also improved the antioxidant metabolities (tocopherol) and enzymes (CAT, POX, SOD) in both species but to more extent in B.napus by 1.98, 2.77, 2.46 and 2.05 fold, respectively. This increase in glucosinolates and antioxidants led to increased brassic In conclusion, although high Sb concetrations is toxic, low natural Sb conecntrations can promote the biomass and bioactive compound accumulation in Brassica spp.