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Boron (B) is an essential microelement for plant growth and has been shown to reduce cadmium (Cd) toxicity in wheat through modulating gene expression. However, there is not enough information about the effects of different applications of B fertilizer on the accumulation of Cd, particularly throughout the wheat growth period. This experiment employed two different B fertilization methods. The soil application method utilized 1.5 mg B kg−1 soil (Cd+B) and foliar application utilized 0.1% (F0.1%), 0.3% (F0.3%), and 0.6% (F0.6%) B concentrations along with 4 mg kg−1 Cd. The results showed that B application in the soil reduced Cd concentrations per plant by 43.9% at the seedling stage, 74.59% in the roots, and 52.11% in the shoots at the elongation stage. At the same time, Cd concentrations in the roots were higher by B application at the anthesis and maturity stages, suggesting that B retains more Cd in the roots. The gray correlation analysis showed that the gray relational coefficients followed the following order: F0.3% > F0.1% > Cd+B > F0.6%. According to quantitative real-time PCR analysis, the six Cd transporters were mostly expressed in the roots at the seedling stage and anthesis stage. In addition, the expression of TCONS1113 , TRIAE1060, and TRIAE5370 showed a negative correlation relationship with Cd concentration at the seedling stage, both in roots and shoots. At the anthesis stage, the expression of TCONS1113 and TRIAE5370 in roots was higher in Cd-treated plants compared to B-treated plants, and a similar tendency was noted for the expression of TRIAE5770 and TRIAE1060 in shoots as well. These results suggest that B application could significantly inhibit Cd uptake and translocation by regulating the expression of Cd transporter genes, especially at the seedling stage and the elongation phase in wheat. [Display omitted] • Boron (B) decreased cadmium (Cd) accumulation at seedling and elongation stages in wheat. • Boron application decreased Cd transport gene expression under Cd stress. • Boron supply improved mineral elements content in grains under Cd stress. • Foliar application of boron was better than soil application in preventing Cd accumulation. [ABSTRACT FROM AUTHOR]

• The application of boron inhibited the absorption of cadmium. • Five highly homologous genes to Cd transporters were identified. • B is an inhibitor for Cd uptake by interfering with the gene expression of Cd transporter. Various nutrients (Mg, Zn, Fe, Mn, Si, etc.) can supress cadmium (Cd) uptake and alleviate Cd toxicity, but the mechanisms are not the same. In this study, the molecular mechanism governing the effects of boron (B) on uptake of Cd in hydroponically grown wheat was characterized. As compared to control (0 μM Cd), B concentration per plant decreased by 22% and 29% under 5 μM Cd and 50 μM Cd treatment respectively. In addition, B application decreased Cd concentration and accumulation in whole wheat. Correlation analysis of different elements show that there was a highly negative correlation between concentrations of B and Cd (r = −0.854 with significant correlation) in wheat. Additionally, 16,543 differentially expressed genes (DEGs) (7666 up- and 8877 down-regulated) were detected between 0 and 5 μM Cd treatments in wheat roots by transcriptome sequencing. Gene ontology functional category and Kyoto encyclopedia of genes and genomes pathway analyses indicated that the DEGs were involved in biological process, cellular component, and molecular function. Five highly homologous genes to Cd transporters were identified; these genes were involved in metal ion binding, transmembrane ion transport, and protein transport. According to the qRT-PCR results, expression of all these genes was down-regulated in the 462 μM of B treatment compared with the 46.2 μM of B treatment regardless of the Cd treatments (0.5 or 5 μM Cd). These results suggest that B is an inhibitor of Cd uptake, and the down-regulation of five highly homologous genes could be associated with decreased uptake of Cd after B application. [ABSTRACT FROM AUTHOR]

Molybdenum (Mo) is an essential trace element for higher plants. Winter wheat cultivar 97003 has a higher Mo efficiency than 97014 under Mo-deficiency stress. Mo efficiency is related to Mo uptake, transfer and assimilation in plants. Several genes are involved in regulating Mo uptake, transfer and assimilation in plants. To obtain a better understanding of the aforementioned difference in Mo uptake, we have conducted a hydroponic trail to investigate the expression of genes related to Mo uptake, transfer and assimilation in the above two cultivars. The results indicate a closed relationship between Mo uptake and TaSultr5.1, TaSultr5.2 and TaCnx1 expression, according to a stepwise regression analysis of the time course of Mo uptake in the two cultivars. Meanwhile, expression of TaSultr5.2 in roots also showed a positive relationship with Mo uptake rates. 97003 had stronger Mo uptake than 97014 at low Mo-application rates (less than 1 μmol Mo L−1) due to the higher expression of TaSultr5.2, TaSultr5.1 and TaCnx1 in roots. On the contrary, Mo uptake of 97003 was weaker than 97014 at high Mo application rates (ranging from 5 to 20 μmol Mo L−1), which was related to significant down-regulation of TaSultr5.2 and TaCnx1 genes in roots of 97003 compared to 97014. Therefore, we speculated that the differential-expression intensities of TaSultr5.2, TaSultr5.1 and TaCnx1 could be the cause of the difference in Mo uptake between the two winter wheat cultivars at low and high Mo application levels. [ABSTRACT FROM AUTHOR]

Screening and breeding of high-Zn-accumulating wheat cultivars have received increasing attention in recent years. However, the exact mechanism of Zn uptake and accumulation in wheat is not fully understood. Here, we investigated the physiological responses and TaZIPs gene expression in a low (Zhengmai0856, ZM0856) and a high (Aikang58, AK58) grain-Zn-accumulating wheat cultivars under hydroponic conditions with different levels of Zn supply. Results showed that AK58 was a Zn sensitive cultivar with better growth advantage, while ZM0856 was a Zn tolerant cultivar with higher capacity of Zn uptake. In addition, gene expression analysis showed that, the expression levels of the TaZIP3 , TaZIP5 , and TaZIP7 in roots were increased in both cultivars under Zn deficiency. In shoots, TaZIP3 and TaZIP 6 transcript accumulation was lower in AK58 than ZM0856, whereas TaZIP7 showed the opposite effect. Moreover, multivariate statistical analysis (Pearson's correlation and PCA) showed that the mechanisms involved in Zn uptake and translocation was closely related to subcellular biosynthesis and ZIP gene expression regulation, whereas adequate Zn supply improved the Zn uptake and root-to-shoot translocation. These novel findings might be helpful for the molecular-assisted selecting and breeding of Zn-rich wheat cultivars. • AK58 showed better performance than ZM0856 under different Zinc concentrations. • Zinc supply reduced the uptake of Fe, Mn, and Cu by both wheat cultivars in the root. • Zinc supply alleviated Zn-deficiency-induced photosynthetic damage and oxidative stress for both wheat cultivars. • Subcellular (cell wall, cell soluble fraction) plays an important role in sequestration and tolerance of high Zn ions. • Zinc uptake and translocation were mediated by the induced expression of these TaZIPs transporters in wheat. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) contamination is a serious challenge in agricultural soils worldwide, resulting in Cd entering the food chain mainly through plant-based food and threatening human health. Minimizing Cd bioaccumulation in wheat is an important way to prevent Cd hazards to humans. Hydroponic and pot experiments were conducted to comprehensively evaluate the effects of zinc sulfate (ZnSO 4) and zinc oxide nanoparticles (nZnO) on Cd uptake, translocation, subcellular distribution, cellular ultrastructure, and gene expression in two wheat genotypes that differ in grain Zn accumulation. Results showed that high-dose nZnO significantly reduced root Cd concentration (52.44%∼56.85%) in two wheats, in contrast to ZnSO 4. The S216 exhibited higher tolerance to Cd compared to Z797. Importantly, Zn supplementation enhanced Cd sequestration into vacuoles and binding to cell walls, which conferred stability to ultracellular structures and photosynthetic apparatus. Down-regulation of influx transporter (TaHMA2 and TaLCT1) and up-regulation of efflux transporters (TaTM20 and TaHMA3) in Z797 might contribute to Zn-dependent alleviation of Cd toxicity and enhance its Cd tolerance. Down-regulation of ZIP transporters (TaZIP3 , -5 , and -7) might contribute to an increase in root Zn concentration and inhibit Cd absorption. Additionally, soil Zn provided an effective strategy for the reduction of grain Cd concentrations in both wheats, with a reduction of 26%∼32% (high ZnSO 4) and 11%∼67% (high nZnO), respectively. Collectively, these findings provide new insights and perspectives on the mechanisms of Cd mitigation in wheats with different Zn fertilizers and demonstrate that the effect of nZnO in mitigating Cd stress is greater than that of ZnSO 4 fertilizers. [Display omitted] • High Zn reduced Cd concentration in wheat roots, while low Zn increased it in shoots. • High-dose ZnO NPs was more effective than ZnSO 4 in alleviating Cd-induced toxicity. • Zn enhances Cd sequestration into vacuoles and chelation onto cell walls. • Zn downregulated TaLCT1 and TaHMA2 expression, while upregulating TaTM20 and TaHMA3. [ABSTRACT FROM AUTHOR]