Protective effect of cerium ion against ultraviolet B radiation-induced water stress in soybean seedlings

Rare earth elements applied to phytoremediation: Enhanced endocytosis promotes remediation of antimony contamination with different valence levels in Solanum nigrum L

Antimony (Sb) pollution poses a noteworthy risk to human health and ecosystem sustainability, therefore effective, eco-friendly, and widely accepted restoration methods are urgently needed. This study introduces a new approach of using La(III) foliar application on Solanum nigrum L. (S. nigrum), a cadmium hyperaccumulator, to improve its photosynthetic and root systems under Sb stress, resulting in a higher biomass. Notably, La(III) also enhances endocytosis in root cells, facilitating efficient and non-selective remediation of both Sb(III) and Sb(V) forms. The absorption of Sb by root cell endocytosis was observed visually with a confocal laser scanning microscope. The subcellular distribution of Sb in the cell wall of S. nigrum is reduced. And the antioxidant enzyme activity system is improved, resulting in an enhanced Sb tolerance in S. nigrum. Based on the existing bibliometric analysis, this paper identified optimal conditions for S. nigrum to achieve maximum translocation and bioconcentration factor values for Sb. The foliar application of La(III) on plants treated with Sb(III), Sb(V), and a combination of both resulted in translocation factor values of 0.89, 1.2, 1.13 and bioconcentration factor values of 11.3, 12.81, 14.54, respectively. Our work suggests that La(III)-enhanced endocytosis of S. nigrum root cells is a promising remediation strategy for Sb-contaminated environments.

Morphological and physiological responses of Heteropogon contortus to drought stress in a dry-hot valley

BACKGROUND

Heteropogon contortus is a valuable pasture species that is widely used for vegetation restoration in dry-hot valleys of China. However, to date, its morphological and physiological responses to drought, and the underlying mechanisms are not well understood. This study was aimed to investigate the morphological and physiological changes of H. contortus under drought stress during the dry-hot season. Heteropogon contortus was planted in pots and subjected to four levels of soil water treatments: above 85 % (control), 70-75 % (light stress), 55-60 % (moderate stress) or 35-40 % (severe stress) of field capacity.

RESULTS

Within the total stress period (0-29 days), H. contortus grew rapidly in the light stress, whereas severe stress had a negative impact on growth. Aboveground biomass decreased together with increasing drought stress, whereas root biomass increased. Consequently, the root/shoot ratio of the severe stress treatment increased by 80 % compared to that of the control treatment. The ratio of bound water/free water (BW/FW) was the most sensitive parameter to drought and showed a value under severe stress that was 152.83 % more than that in the control treatment. Although leaf water potential (LWP) and leaf relative water content (RWC) decreased with progressive water stress, H. contortus managed to maintain a relatively high RWC (nearly 70 %) in the severe stress condition. We also detected a significant reduction (below 0.6) in the ratio of variable fluorescence/maximum fluorescence (Fv/Fm) in the severe stress treatment.

CONCLUSIONS

Our results show that H. contortus adapts to drought mainly by avoidance mechanisms, and its morphological and physiological characteristics are inhibited under severe stress, but can recover at a certain time after re-watering. These findings might help limited water resources to be fully used for vegetation management in the studied region.

Effects of ion beams pretreatment on damage of UV-B radiation on seedlings of winter wheat (Triticum aestivum L.)

The seeds of winter wheat were pretreated with three different doses of low-energy N(+) beams, and its seedlings were subjected to UV-B irradiation (10.08 kJ m(-2) day(-1)) at three-leaves stage. The growth characteristic of seeds, the oxidative damage to membrane system induced by UV-B radiation, and the alleviating effects of N(+) beams pretreatment to radiation damage were investigated. The results showed that the germination rate and seedling rate, respectively, increased 14.09 ± 1.03 and 13.91 ± 1.21 % compared with control (CK) at the dose of 4.0 × 10(16) ions/cm(2). When seedlings were exposed to UV-B radiation, the pretreatment method under the dose of 4.0 × 10(16) ions/cm(2) made the activity of peroxidase and superoxide dismutase increasing, the content of chlorophyll enhancing, but the content of malondialdehyde reducing significantly compared with that of the single UV-B radiation. Whereas, the activity of catalase irradiated by UV-B improved notably under the pretreatment dose of 8.0 × 10(16) ions/cm(2). In addition, after being irradiated with UV-B, the content of soluble protein and glutathione whose seeds were pretreated by the dose of 6.0 × 10(16) ions/cm(2) were higher than that of the single UV-B radiation. It was suggested that the suitable dose of low-energy ion beams pretreatment to wheat seeds could change its physiological characteristics at seedlings stage to alleviate the damage effects from UV-B radiation.