Abscisic acid (ABA) is a drought-stress-responsive hormone that plays an important role in the stomatal activity of plant leaves. Currently, ABA glycosides have been identified in apples, but their glycosyltransferases for glycosylation modification of ABA are still unidentified. In this study, the mRNA expression of glycosyltransferase gene MdUGT73AR4 was significantly up-regulated in mature apple leaves which were treated in drought stress by Real-Time PCR. It was hypothesised that MdUGT73AR4 might play an important role in drought stress. In order to further characterise the glycosylation modification substrate of glycosyltransferase MdUGT73AR4, we demonstrated through in vitro and in vivo functional validation that MdUGT73AR4 can glycosylate ABA. Moreover, the overexpression lines of MdUGT73AR4 significantly enhance its drought stress resistance function. We also found that the adversity stress transcription factor AREB1B might be an upstream transcription factor of MdUGT73AR4 by bioinformatics, EMSA, and ChIP experiments. In conclusion, this study found that the adversity stress transcription factor AREB1B was significantly up-regulated at the onset of drought stress, which in turn positively regulated the downstream glycosyltransferase MdUGT73AR4, causing it to modify ABA by mass glycosylation and promoting the ABA synthesis pathway, resulting in the accumulation of ABA content, and displaying a stress-resistant phenotype.

Background: Tanshinone IIA (Tan IIA) is a lipophilic active constituent derived from the rhizomes and roots of Salvia miltiorrhiza Bunge (Danshen), a common Chinese medicinal herb. However, clinical applications of Tan IIA are limited due to its poor solubility in water. Methods: To overcome this limitation, we developed a calcium alginate hydrogel (CA) as a hydrophilic carrier for Tan IIA, which significantly improved its solubility. We also prepared nanoparticles with pH-responsive properties to explore their potential for controlled drug delivery. The physicochemical properties of Tan IIA/CA nanoparticles were evaluated, including their size, stability, and release profile. We also utilized RNA sequencing to further investigate the underlying anticancer mechanisms of Tan IIA/CA nanoparticles. Results: The Tan IIA/CA nanoparticles demonstrated enhanced solubility and exhibited potent anticancer activity in vitro. Additionally, the nanoparticles showed promising pH-responsive behavior, which is beneficial for controlled release applications. Further investigation into the molecular mechanisms revealed that the anticancer effects of Tan IIA/CA were mediated through apoptosis, ferroptosis, and autophagy pathways. Conclusions: This study confirms the anticancer potential and mechanisms of Tan IIA, while also presenting an innovative approach to enhance the solubility of this poorly soluble compound. The use of CA-based nanoparticles could be a valuable strategy for improving the therapeutic efficacy of Tan IIA in cancer treatment.

Nicosulfuron, an acetolactate synthase (ALS) inhibitor herbicide, is a broad-spectrum and highly effective post-emergence herbicide. Glycosyltransferases (GTs) are widely found in organisms and transfer sugar molecules from donors to acceptors to form glycosides or sugar esters, thereby altering the physicochemical properties of the acceptor molecule, such as participating in detoxification. In this study, nine glycosyltransferases in group D of the apple glycosyltransferase family I were predicted to possibly be involved in the detoxification metabolism of ALS-inhibiting herbicides based on gene chip data published online. In order to confirm this, we analysed whether the expression of the nine glycosyltransferase genes in group D was induced by the previously reported ALS-inhibiting herbicides by real-time PCR (polymerase chain reaction). It was found that the ALS-inhibiting herbicide nicosulfuron significantly increased the expression of the MdUGT73CG22 gene in group D. Further investigation of the mechanism of action revealed that the apple glycosyltransferase MdUGT73CG22 glycosylated and modified nicosulfuron both in vivo and ex vivo to form nicosulfuron glycosides, which were involved in detoxification metabolism. In conclusion, a new glycosyltransferase, MdUGT73CG22, was identified for the first time in this study, which can glycosylate modifications of the ALS-inhibiting herbicide nicosulfuron and may be involved in the detoxification process in plants, which can help to further improve the knowledge of the non-targeted mechanism of herbicides.

Sulcotrione is a member of triketone herbicides, a class of HPPD (4-hydroxyphenylpyruvate dioxygenase) inhibitors with broad-spectrum herbicidal activity. Modifications of glycosylation mediated by glycosyltransferases (GT) are involved in plant detoxification. In this study, we analyzed chip data published online and found that eight glycosyltransferases from group A of the apple glycosyltransferase family 1 may be involved in the metabolic mechanism of detoxification of triketone herbicides. To verify this prediction, we induced apple seedlings with six types of triketone herbicides, and then detected the expression levels of eight glycosyltransferase genes through real-time PCR. We found that triketone herbicides induced up-regulation of eight glycosyltransferase genes to varying degrees, with MdUGT91AJ2 being the most significantly up-regulated by sulcotrione-induced glycosyltransferase gene expression. Then, through in vitro enzymatic reactions and HPLC identification of glycoside substrates, it was found that the glycosyltransferase MdUGT91AJ2 had the highest specific enzyme activity against the triketone herbicide sulcotrione. Furthermore, the in vivo mechanism of the glycosyltransferase MdUGT91AJ2 in the detoxification metabolism of sulcotrione was further validated by overexpressing the strain in the plant. HPLC analysis showed that the content of sulcotrione glycosides in the overexpressing strain of MdUGT91AJ2 was significantly higher than that in the wild type. This result indicated that the apple glycosyltransferase MdUGT91AJ2 can still glycosylate and modify sulfotrione in plants, and participate in its detoxification metabolism. In summary, this study identified for the first time a novel apple glycosyltransferase MdUGT91AJ2 and elucidated its mechanism of action in the detoxification and metabolism of the triketone herbicide sulfotriene.