Mitigating cadmium accumulation in dicotyledonous vegetables by iron fertilizer through inhibiting Fe transporter IRT1-mediated Cd uptake.

The solubility of cadmium (Cd) in soil and its transfer to plants are influenced by soil pH. While increasing soil pH reduces Cd solubility and accumulation in rice plants grown in acidic soils, its effect on Cd accumulation in vegetables remains inconclusive. Here, we investigated the impact of soil pH on Cd accumulation in dicotyledonous vegetables and elucidated the underlying molecular mechanisms. Soils collected from various locations were supplemented with varying quantities of lime to achieve soil pH values of around 5.0, 6.0, 7.0, and 8.0. Raising soil pH from around 5.0 to 8.0 markedly decreased extractable Cd. However, increasing soil pH tended to promote shoot Cd accumulation in dicotyledonous vegetable species including lettuce, pakchoi, and Chinese cabbage, and the model dicotyledonous plant Arabidopsis thaliana. Conversely, soil pH increase resulted in a monotonic decrease in rice Cd accumulation. In our hydroponic experiments, we discovered that iron (Fe) deficiency substantially increased Cd uptake and accumulation in dicotyledonous plants but not in rice. Increasing soil pH reduced soil Fe availability and induced the Fe transporter gene IRT1 expression in dicotyledonous vegetables roots, which led to an increase in IRT1-mediated Cd uptake and subsequently increased Cd accumulation as soil pH increases. A comprehensive model incorporating extractable Cd and root IRT1 expression better explained Cd accumulation in vegetable shoots. The application of 50 mg/kg of Fe fertilizer in neutral or alkaline soils resulted in a significant reduction in Cd accumulation by 34-58% in dicotyledonous vegetables. These findings reveal that increasing soil pH has two opposite effects, decreasing soil Cd availability while promoting Cd uptake through IRT1 upregulation, reconciling the inconsistency in its effect on Cd accumulation in dicotyledonous plants. Our findings provide important insights for understanding the factors affecting Cd uptake in plants and offer a practical solution to mitigate Cd contamination in vegetables.

Tussilagone inhibits allergic responses in OVA-induced allergic rhinitis guinea pigs and IgE-stimulated RBL-2H3 cells.

Farfarae Flos is the dried flower buds of Tussilago farfara L. which is widely used to treat allergic and inflammatory diseases in Chinese folk. Tussilagone (TSL), a sesquiterpene compound purified from Farfarae Flos, has been confirmed the main active component in the plant. However, its anti-allergic activity hasn't been reported yet. The purpose of this study is to investigate the anti-allergic effect of TSL in ovalbumin (OVA)-induced allergic rhinitis (AR) guinea pigs and immunoglobulin E (IgE)-stimulated RBL-2H3 cells. The AR symptoms such as nasal scratching, sneezing and runny nose were scored and the histological changes of nasal mucosa were observed by H&E staining. The levels of histamine, OVA-specific IgE, IL-6 and TNF-α in the serum were measured by ELISA. In IgE-stimulated RBL-2H3 cells, the phosphoryration of Lyn, Syk, Akt, NF-κB p65, ERK and p38 MAPK were investigated by western blot analysis. The results showed that intraperitoneal injection of TSL at doses of 25 and 50 mg/kg significantly alleviated the allergic symptoms and the histological changes of nasal mucosa in OVA-induced allergic rhinitis guinea pigs. Moreover, the levels of histamine, IgE and IL-6 in the serum decreased significantly (p < .05). In vitro, TSL suppressed the phosphorylation of Lyn, Syk, Akt, NF-κB p65, ERK and p38 MAPK in IgE-stimulated RBL-2H3 cells. These results indicate TSL has therapeutic effect on allergic rhinitis in guinea pigs. The anti-allergic mechanism may be through the inhibition of allergic and inflammatory related pathways in mast cells.