Zelin Xia

UDP-glycosyltransferases (UGTs) represent a large multigene family that play a central role in glycosylating a highly diverse array of natural products, underscoring their critical importance in various biological processes. However, the functional roles of a substantial majority of UGTs remain to be elucidated. In the present study, we characterized the glycosyltransferase UGT78G3, a member of the UGT78 glycosyltransferase family in the model legume Medicago truncatula. Amino-acid sequence analysis revealed a conserved PSPG motif at the C-terminus of UGT78G3. Liquid chromatography-coupled tandem mass spectrometry (LC-MS/MS) analysis demonstrated that UGT78G3 catalyzes the formation of kaempferol 3-O-glucoside in vitro. However, neither UGT78G3 overexpression nor CRISPR/Cas9-mediated mutagenesis resulted in significant changes to the endogenous levels of kaempferol 3-O-glucoside, indicating that UGT78G3 does not play a predominant role in the biosynthesis of kaempferol 3-O-glucoside in vivo. Our findings identify a putative glycosyltransferase in M. truncatula and provide a target for biocatalyst design aimed at synthesizing flavonoid glucosides.

Salt stress has a detrimental impact on food crop production, with its severity escalating due to both natural and man-made factors. As one of the most important food crops, wheat is susceptible to salt stress, resulting in abnormal plant growth and reduced yields; therefore, damage from salt stress should be of great concern. Additionally, the utilization of land in coastal areas warrants increased attention, given diminishing supplies of fresh water and arable land, and the escalating demand for wheat. A comprehensive understanding of the physiological and molecular changes in wheat under salt stress can offer insights into mitigating the adverse effects of salt stress on wheat. In this review, we summarized the genes and molecular mechanisms involved in ion transport, signal transduction, and enzyme and hormone regulation, in response to salt stress based on the physiological processes in wheat. Then, we surveyed the latest progress in improving the salt tolerance of wheat through breeding, exogenous applications, and microbial pathways. Breeding efficiency can be improved through a combination of gene editing and multiple omics techniques, which is the fundamental strategy for dealing with salt stress. Possible challenges and prospects in this process were also discussed.

Leaf senescence is an important factor affecting the functional transition from nutrient assimilation to nutrient remobilization in crops. The senescence of wheat leaves is of great significance for its yield and quality. In the leaf senescence process, transcriptional regulation is a committed step in integrating various senescence-related signals. Although the plant-specific transcriptional regulation factor valine-glutamine (VQ) gene family is known to participate in different physiological processes, its role in leaf senescence is poorly understood. We isolated TaVQ25-A and studied its function in leaf senescence regulation. TaVQ25-A was mainly expressed in the roots and leaves of wheat. The TaVQ25-A-GFP fusion protein was localized in the nuclei and cytoplasm of wheat protoplasts. A delayed senescence phenotype was observed after dark and abscisic acid (ABA) treatment in TaVQ25-A-silenced wheat plants. Conversely, overexpression of TaVQ25-A accelerated leaf senescence and led to hypersensitivity in ABA-induced leaf senescence in Arabidopsis. A WRKY type transcription factor, TaWRKY133, which is tightly related to the ABA pathway and affects the expression of some ABA-related genes, was found to interact with TaVQ25-A both in vitro and in vivo. Results of this study indicate that TaVQ25-A is a positive regulator of ABA-related leaf senescence and can be used as a candidate gene for wheat molecular breeding.