Proteomic and Biochemical Evidence Involving Root Cell Wall Biosynthesis and Modification, Tricarboxylic Acid Cycle, and Glutathione Metabolism in Cultivar-Dependent Cd Accumulation of Water Spinach (Ipomoea aquatica).

Proteomic analysis and biochemical tests were employed to investigate the critical biological processes responsible for the different cadmium (Cd) accumulations between two water spinach (Ipomoea aquatica) cultivars, QLQ and T308. QLQ, with lower shoot Cd accumulation and translocation factor than T308, possessed higher expression of cell wall biosynthesis and modification proteins in roots, together with higher lignin and pectin contents, higher pectin methylesterase activity, and lower pectin methylation. The results demonstrated that QLQ could more effectively restrict root-to-shoot Cd translocation by compartmentalizing more Cd in root cell walls. In contrast, T308 showed higher expression of the tricarboxylic acid (TCA) cycle, glutathione (GSH) metabolism, and heavy metal transporter proteins, accompanied by higher GSH content and glutathione S-transferase (GST) and glutathione reductase (GR) activity, which accelerated Cd uptake and translocation in T308. These findings revealed several critical biological processes responsible for cultivar-dependent Cd accumulation in water spinach, which are important for elucidating Cd accumulation and transport mechanisms in different cultivars.

Molecular and biochemical mechanisms underlying boron-induced alleviation of cadmium toxicity in rice seedlings.

Both cadmium (Cd) contamination and boron (B) deficiency in farmland soils pose a threat to the yield and quality of crops in Southern China. The present study investigated the mechanisms by which B reduces Cd accumulation in rice (Oryza sativa) seedlings. Boron supplementation partially restored the decline in shoot and root biomass caused by Cd treatment (26% and 33%, respectively), with no significant difference between the B+Cd and control groups. We also found that B significantly reduced shoot and root Cd concentrations (by 64% and 25%, respectively) but increased Cd concentration (by 43%) and proportion (from 38% to 55%) in root cell walls. Transcriptome analysis and biochemical tests suggested that B supplementation enhanced lignin and pectin biosynthesis, pectin demethylation, and sulfur and glutathione metabolism. Moreover, B decreased the expression of some Cd-induced transporter-related genes (i.e., HMA2, Nramp1, and several ABC genes). These results indicate that B relieved Cd toxicity and reduced Cd accumulation in rice seedlings by restraining Cd uptake and translocation from root to shoot by improving Cd tolerance and chelation ability. These novel findings would benefit further investigations into how B influences Cd uptake, translocation, detoxification, and accumulation in crops.