Effect of lanthanum on rooting of in vitro regenerated shoots of Saussurea involucrata Kar. et Kir

Application of Lanthanum at the Heading Stage Effectively Suppresses Cadmium Accumulation in Wheat Grains by Downregulating the Expression of TaZIP7 to Increase Cadmium Retention in Nodes

Reducing cadmium (Cd) accumulation in wheat is an effective way to decrease the potential threats of Cd to human health. The application of lanthanum (La) in agricultural fields is eliciting extensive attention due to its beneficial effects on improving yields and inhibiting Cd accumulation in edible parts of crops. However, the potential mechanism of La-restricted Cd accumulation in crop grains is not entirely understood. Here, we investigated the effects of La and Cd accumulation in wheat grains by implementing application at the shooting and heading stages. Some associated mechanisms were explored. Results showed that La application at the shooting and heading stages considerably promoted the thousand-grain weight. La application at the shooting and heading stages increased Cd accumulation in the first node beneath the panicle (N1) but reduced Cd levels in the other tissues. La application at the heading stage exerted greater effects on Cd storage in N1 while reducing Cd concentrations in the other tissues compared with La application at the shooting stage. La addition substantially decreased the translocation of Cd from the lower nodes to the upper internodes, but increased Cd translocation from the lower internodes to the upper nodes. The expression of TaZIP7 in N1 was downregulated by La treatment. These results suggest that the effective reduction in Cd in wheat grains by La application at the heading stage is probably a consequence of the successful promotion of Cd storage in nodes by downregulating the expression of TaZIP7 during the grain-filling stage, thereby hindering the redirection Cd from nodes to grains.

Rare earth metallic elements in plants: assessing benefits, risks and mitigating strategies

Rare earth elements (REEs) comprises of a uniform group of lanthanides and scandium (Sc) and yttrium (Y) finding their key importance in agriculture sectors, electronic and defense industries, and renewable energy production. The immense application of REEs as plant growth promoters has led to their undesirable accumulation in the soil system raising concerns for REE pollution as upcoming stresses. This review mainly addresses the chemistry of REEs, uptake and distribution and their biphasic responses in plant systems and possible plausible techniques that could mitigate/alleviate REE contamination. It extends beyond the present understanding of the biphasic impacts of rare earth elements (REEs) on physio-biochemical attributes. It not only provides landmarks for further exploration of the interrelated phytohormonal and molecular biphasic nature but also introduces novel approaches aimed at mitigating their toxicities. By delving into innovative strategies such as recycling, substitution, and phytohormone-assisted mitigation, the review expands upon existing knowledge of REEs whilst also offering pathways to tackle the challenges associated with REE utilization.

Lanthanum Promotes Bahiagrass (Paspalum notatum) Roots Growth by Improving Root Activity, Photosynthesis and Respiration

Lanthanum (La), one of the most active rare earth elements, promotes the growth of turfgrass roots. In this study, the mechanisms by which La influences bahiagrass (Paspalum notatum) growth were evaluated by the analyses of root growth, root activity, cell wall polysaccharide content, respiration intensity, ascorbic acid oxidase (AAO) and polyphenol oxidase (PPO) activity, the subcellular distribution of mitochondria, transcription in roots, photosynthetic properties, chlorophyll fluorescence parameters, and chlorophyll content. The application of 0.3 mM La³⁺ increased root activity, respiration intensity, AAO activity, and the number of mitochondria in the mature cells of bahiagrass roots. La could significantly improve the net photosynthetic rate, transpiration rate, and chlorophyll fluorescence of bahiagrass. Differentially expressed genes identified by high-throughput transcriptome sequencing were enriched for GO (Gene Ontology) terms related to energy metabolism and were involved in various KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways, including oxidative phosphorylation, TCA (Tricarboxylic Acid) cycle, and sucrose metabolism. These findings indicate that La promotes bahiagrass root growth by improving root activity, photosynthesis, and respiration, which clarifies the mechanisms underlying the beneficial effects of La and provides a theoretical basis for its use in artificial grassland construction and ecological management projects.

Interactive Effects of Lanthanum and Calcium on Cadmium Accumulation in Wheat with Special Reference to TaNramp5 Expression Regulated by Calmodulin

Lanthanum (La), calcium (Ca), and cadmium (Cd) have similar physical and chemical properties because of their similar ionic radius. Although the interactions between La, Ca, and Cd have been frequently reported in plants, few studies have investigated the interactive effects of La and Ca on the growth and Cd accumulation in plants. Therefore, we investigated the interactive effects of La and Ca on the growth and Cd accumulation in wheat under Cd exposure by a hydroponic experiment. The results indicated that wheat growth was significantly affected by La-Cd and La-Ca interactions. The accumulation of Cd in wheat was significantly affected by La-Ca and La-Cd interactions and La-Ca-Cd interplay. Correlation analysis indicated that Ca deficiency stimulated La to promote wheat growth and mitigate Cd toxicity. Simultaneously, a low Ca supply stimulated La to decrease Cd accumulation in wheat and induce TaNramp5 expression. In addition, Cd accumulation in wheat was significantly affected by the W7-La interaction and W7-La-Ca interplay. All of the results suggested that La, Ca, and Cd probably share the same binding sites in calmodulin (TaCaM) and La could affect Cd accumulation in wheat by interacting with TaCaM and then downregulating the expression of TaNramp5.

Lanthanum Prolongs Vase Life of Cut Tulip Flowers by Increasing Water Consumption and Concentrations of Sugars, Proteins and Chlorophylls

We evaluated the effect of separately adding two sources of lanthanum (La), LaCl₃ and La(NO₃)₃ × 6H₂O at a concentration of 40 µM each, to the preservative solution of 15 cut tulip flower varieties. Ascorbic acid (AsA; 0.2 g/L) was used as a reference solution, while distilled water was used as control. The variety Laura Fygi recorded the longest vase life with 13 days. The highest water consumption per gram of stem fresh biomass weight (FBW) (2.5 mL) was observed in the variety Violet Beauty, whereas the lowest (1.098 mL) was recorded in Pink Impression. At the end of the vase life period, higher concentrations of total soluble sugars in petals and total soluble proteins in leaves were recorded in La-treated stems, compared to the AsA treatment and the control. Additionally, La(NO₃)₃ × 6H₂O supply increased the fresh weight of stems in vase and prolonged vase life. Moreover, this treatment resulted in the highest foliar concentration of chlorophylls at the end of vase life. Therefore, La increases tulip flower vase life as a consequence of improving the concentrations of some vital biomolecules.

Combined effects of lanthanum(III) and elevated ultraviolet-B radiation on root growth and ion absorption in soybean seedlings

Rare earth element accumulation in the soil and elevated ultraviolet (UV)-B radiation (280-315 nm) are important environmental issues worldwide. To date, there have been no reports concerning the combined effects of lanthanum (La)(III) and elevated UV-B radiation on plant roots in regions where the two issues occur simultaneously. Here, the combined effects of La(III) and elevated UV-B radiation on the growth, biomass, ion absorption, activities, and membrane permeability of roots in soybean (Glycine max L.) seedlings were investigated. A 0.08 mmol L(-1) La(III) treatment improved the root growth and biomass of soybean seedlings, while ion absorption, activities, and membrane permeability were obviously unchanged; a combined treatment with 0.08 mmol L(-1) La(III) and elevated UV-B radiation (2.63/6.17 kJ m(-2) day(-1)) exerted deleterious effects on the investigated indices. The deleterious effects were aggravated in the other combined treatments and were stronger than those of treatments with La(III) or elevated UV-B radiation alone. The combined treatment with 0.24/1.20 mmol L(-1) La(III) and elevated UV-B radiation exerted synergistically deleterious effects on the growth, biomass, ion absorption, activities, and membrane permeability of roots in soybean seedlings. In addition, the deleterious effects of the combined treatment on the root growth were due to the inhibition of ion absorption induced by the changes in the root activity and membrane permeability.

Influence of rare earth elements on metabolism and related enzyme activity and isozyme expression in Tetrastigma hemsleyanum cell suspension cultures

The effects of rare earth elements (REEs) not only on cell growth and flavonoid accumulation of Tetrastigma hemsleyanum suspension cells but also on the isoenzyme patterns and activities of related enzymes were studied in this paper. There were no significant differences in enhancement of flavonoid accumulation in T. hemsleyanum suspension cells among La(3+), Ce(3+), and Nd(3+). Whereas their inductive effects on cell proliferation varied greatly. The most significant effects were achieved with 100 μM Ce(3+)and Nd(3+). Under treatment over a 25-day culture period, the maximal biomass levels reached 1.92- and 1.74-fold and the total flavonoid contents are 1.45- and 1.49-fold, than that of control, respectively. Catalase, phenylalanine ammonia-lyase (PAL), and peroxidase (POD) activity was activated significantly when the REE concentration range from 0 to 300 μM, whereas no significant changes were found in superoxide dismutase activity. Differences of esterase isozymes under REE treatment only laid in expression level, and there were no specific bands. The expression level of some POD isozymes strengthened with increasing concentration of REEs within the range of 50-200 μM. When REE concentration was higher than 300 μM, the expression of some POD isozymes was inhibited; meanwhile, some other new POD isozymes were induced. Our results also showed REEs did not directly influence PAL activity. So, we speculated that 50-200 μM REEs could activate some of antioxidant enzymes, adjust some isozymes expression, trigger the defense responses of T. hemsleyanum suspension cells, and stimulate flavonoid accumulation by inducing PAL activity.