A dose-dependent effect of UV-328 on photosynthesis: Exploring light harvesting and UV-B sensing mechanisms.

Benzotriazole ultraviolet (UV) stabilizers (BUVs) have emerged as significant environmental contaminants, frequently detected in various ecosystems. While the toxicity of BUVs to aquatic organisms is well-documented, studies on their impact on plant life are scarce. Plants are crucial as they provide the primary source of energy and organic matter in ecosystems through photosynthesis. This study investigated the effects of UV-328 (2-(2-hydroxy-4',6'-di-tert-amylphenyl) benzotriazole) on plant growth indices and photosynthesis processes, employing conventional physiological experiments, RNA sequencing (RNA-seq) analysis, and computational methods. Results demonstrated a biphasic response in plant biomass and the maximum quantum yield of PS II (Fv/Fm), showing improvement at a 50 µM UV-328 treatment but reduction under 150 µM UV-328 exposure. Additionally, disruption in thylakoid morphology was observed at the higher concentration. RNA-seq and qRT-PCR analysis identified key differentially expressed genes (light-harvesting chlorophyll-protein complex Ⅰ subunit A4, light-harvesting chlorophyll b-binding protein 3, UVR8, and curvature thylakoid 1 A) related to photosynthetic light harvesting, UV-B sensing, and chloroplast structure pathways, suggesting they may contribute to the observed alterations in photosynthesis activity induced by UV-328 exposure. Molecular docking analyses further supported the binding affinity between these proteins and UV-328. Overall, this study provided comprehensive physiological and molecular insights, contributing valuable information to the evaluation of the potential risks posed by UV-328 to critical plant physiological processes.

N fertilizers promote abscisic acid-catabolizing bacteria to enhance heavy metal phytoremediation from metalliferous soils.

Bacterial-assisted phytoextraction is an attractive strategy to enhance the phytoremediation efficiency of heavy metal (HM)-contaminated soils. In the present study, we investigated the synergistic effects of N fertilizers and abscisic acid (ABA)-catabolizing bacteria on the HM (Cd, Zn, and Pb) phytoremediation efficiency of Brassica juncea L. (B. juncea). Compared with Rhodococcus qingshengii (R. qingshengii) alone, urea, ammonium­nitrogen (NH4+-N), and nitrate­nitrogen (NO3--N) fertilizers combined with R. qingshengii increased HM concentrations in B. juncea by 13.8 %-48.2 %, 44.2 %-54.4 %, and 59.4 %-113.6 %, respectively, and enhanced the biomass of B. juncea by 7.7 %-38.8 %, 10.9 %-29.5 %, and 19.9 %-46.8 %, respectively. Consequently, the bioconcentration factor increased by 3.4 %-30.9 % and the phytoextraction rate increased by 18.5 %-98.7 %. Treatment with NO3--N showed the most significant effect. In structural equation modeling, R. qingshengii inoculation showed greater path coefficients with soil pH and ABA and indoleacetic acid concentrations of B. juncea than N fertilization, indicating that R. qingshengii contributed more to HM extraction efficiency than N fertilizers. Additionally, differences in the extraction rates of Cd, Zn, and Pb from B. juncea were reduced following N fertilization. In summary, synergistic R. qingshengii inoculation and N fertilization have substantial potential to enhance phytoremediation efficiency. Combined application of R. qingshengii and NO3--N fertilizers is recommended.

Synergistic interplay between ABA-generating bacteria and biochar in the reduction of heavy metal accumulation in radish, pakchoi, and tomato.

Heavy metal (HM) contamination is an environmental concern that threatens the agricultural product safety and human health. To address this concern, we developed a novel strategy involving the synergistic application of Azospirillum brasilense, a growth-promoting rhizobacterium which produces abscisic acid (ABA), and biochar to minimize HM accumulation in the edible parts of vegetable crops. Compared to A. brasilense or biochar alone, the concentrations of Cd, Ni, Pb, and Zn in radish (Raphanus sativus L.), pakchoi (Brassica chinensis L.), and tomato (Lycopersicon esculentum L.) decreased by 18-63% and 14-56%, respectively. Additionally, the synergistic treatment led to a 14-63% decrease in the bioconcentration factor. The biomass of the edible parts of the three crops increased by 65-278% after synergistic treatment, surpassing the effects of single treatments. Furthermore, the synergistic application enhanced the SPAD values by 1-45% compared to single treatments. The MDA concentrations in stressed plants decreased by 16-39% with the bacteria-biochar co-treatment compared to single treatments. Co-treatment also resulted in increased soluble protein and sugar concentrations by 8-174%, and improvements in flavonoids, total phenols, ascorbic acid, and DPPH levels by 2-50%. Pearson correlation analysis and structural equation modeling revealed that the synergistic effect was attributed to the enhanced growth of A. brasilense facilitated by biochar and the improved availability of HMs in soils. Notably, although ABA concentrations were not as high as those achieved with A. brasilense alone, they were maintained at relatively high levels. Overall, the synergistic application of A. brasilense-biochar might have remarkable potential for reducing the accumulation of HMs while promoting growth and improving nutritional and antioxidant qualities in tuberous, leafy, and fruit crops.

[Expression and significance of TGF-beta1 and BMP-2 in mandibular callus].

OBJECTIVE: To investigate the expressions of transforming growth factor beta1 (TGF-beta1) and bone morphogenetic protein-2 (BMP-2) in human mandible fracture callus and their quantity changes in the process of healing. METHOD: Thirty callus samples from the fractured mandible bone stumps were collected during operation, and two callus samples were collected from the angle-square jaw patients as controls. The expressions of TGF-beta1 and BMP-2 were test by the immunohistochemistry technic-SABC-staining in different periods of human fractured mandibular callus and in osseous tissue of normal angle of mandible. RESULT: The TGF-beta1 and BMP-2 were expressed in callus of different periods but not in normal bone tissue. The expression of TGF-beta1 increased slowly during the first three weeks after fracture and reached its maximum in the third week, and then weakened gradually. The expression of BMP-2 increased gradually during the first two weeks after fracture and reached its maximum in the second week, then the expression weakened gradually. CONCLUSION: (1) BMP-2 may be one of the factors promoting the repair of fracture. (2) TGF-beta1 could be another signal pathway in repairment of fracture. (3) There could exist some synergistic effects between TGF-beta1 and BMP-2 in the process of fracture healing.