Assessment of Salicylic Acid as a Pretreatment on Alleviating Cadmium Toxicity on In Vitro Banana Shoots

Heavy metals affect human health through the physical contact with polluted soil, polluted water, and food contaminated with toxic metals. Cadmium (Cd) toxicological effects remain for many years in the ecosystem. In this study, in vitro growth of banana ( Musa acuminata ) shoots was evaluated under different concentrations of Cd (0, 50, 100, 200, 500 and 1000 μM) on MS gelled medium for two subsequent subcultures. Also, salicylic acid (SA) was studied as a pretreatment to assess Cd tolerance in banana shoots, using different concentrations (0, 0.5 and 1.0 mM). Cd toxicity decreased plantlet height, as well as fresh and dry biomass at all concentrations evaluated. The highest reduction was observed at the 2nd subculture (2S) on Cd medium at 200 μM, ending with shoot death at 500 μM. However, SA pretreated banana shoots exhibited a better performance, even in 2S and under the culture in high Cd-containing media, compared to non-pretreated shoots, and this protective effect was higher at the SA concentration of 0.5 μM than at 1 μM. The high performance due to 0.5 mM SA included shoots survival, plantlet length, biomass, photosynthetic pigments, and proline content. To our knowledge, this is the first study to examine the effect of Cd on in vitro banana shoots for two successive subcultures, as well as to give a significant indication of the role of SA as a pretreatment in alleviating the toxicity of Cd, even at high concentrations. Findings of this study concluded that SA has a great and extended influence on reducing the harmful effects of Cd in banana. Graphical Abstract