Ubiquitination is a major type of post-translational modification of proteins in eukaryotes. The plant U-Box (PUB) E3 ligase is the smallest family in the E3 ligase superfamily, but plays a variety of essential roles in plant growth, development and response to diverse environmental stresses. Hence, PUBs are potential gene resources for developing climate-resilient crops. However, there is a lack of review of the latest advances to fully understand the powerful gene family. To bridge the gap and facilitate its use in future crop breeding, we comprehensively summarize the recent progress of the PUB family, including gene evolution, classification, biological functions, and multifarious regulatory mechanisms in plants.

Wheat (Triticum aestivum) is particularly susceptible to water deficit at the jointing stage of its development. Sucrose non-fermenting 1-related protein kinase 2 (SnRK2) acts as a signaling hub in the response to drought stress, but whether SnRK2 helps plants cope with water deficit via other mechanisms is largely unknown. Here, we cloned and characterized TaSnRK2.10, which was induced by multiple abiotic stresses and phytohormones. Ectopic expression of TaSnRK2.10 in rice (Oryza sativa) conferred drought tolerance, manifested by multiple improved physiological indices, including increased water content, cell membrane stability, and survival rates, as well as decreased water loss and accumulation of H₂O₂ and malonaldehyde. TaSnRK2.10 interacted with and phosphorylated early responsive to dehydration 15 (TaERD15) and enolase 1 (TaENO1) in vivo and in vitro. TaERD15 phosphorylated by TaSnRK2.10 was prone to degradation by the 26S proteasome, thereby mitigating its negative effects on drought tolerance. Phosphorylation of TaENO1 by TaSnRK2.10 may account for the substantially increased levels of phosphoenolpyruvate (PEP), a key metabolite of primary and secondary metabolism, in TaSnRK2.10-overexpressing rice, thereby enhancing its viability under drought stress. Our results demonstrate that TaSnRK2.10 not only regulated stomatal aperture and the expression of drought-responsive genes, but also enhanced PEP supply and promoted the degradation of TaERD15, all of which enhanced drought tolerance.

Nitrogen (N) fertilization is known to influence soil microbial communities and crop yield, but how N affects the bacterial community and the link to crop yield across different soil types remains poorly understood. Here, we conducted three 5-year stationary field experiments to explore the effect of N fertilization (0, 180, 240, and 300 kg ha⁻¹; termed N0, N1, N2, and N3, respectively) with different soil types (fluvo-aquic soil, FS; sandy soil, SS; lime concretion black soil, BS) on bacterial communities and the relationships among soil, microbes, and N-cycling functional genes to further investigate the effects on wheat yield. The results showed that the N2 treatment (240 kg ha⁻¹) achieved the highest wheat yield, with significantly lower yields in SS than those in FS and BS. N fertilization significantly altered soil physicochemical properties, with a notable decrease in pH, particularly in SS, and an increase in NO₃⁻-N content. Bacterial α-diversity significantly decreased with N application in SS but not in FS and BS, and NO₃⁻-N played a primary role in shaping beta diversity in FS and BS. There were 43, 62, and 11 bacterial species that changed significantly from phylum to genus in the FS, SS, and BS, respectively. The abundance of nitrification genes increased with N fertilization in FS and SS, and N-cycling genes were significantly associated with soil properties. Partial Least Squares Path Modeling (PLS-PM) revealed that N fertilizer affected soil properties, which in turn regulated bacterial communities, and ultimately influenced wheat yield, explaining 67.4% of the yield variation. This study highlights the soil-specific responses to N application, providing a basis for optimizing N management and enhancing agricultural sustainability.

This study uses proteomic technology to identify differentially expressed proteins (DEPs) under varying nitrogen fertilizer levels. Additionally, it utilizes weighted gene co-expression network analysis (WGCNA) based on expression data of DEP-coding genes to explore the mechanism by which nitrogen promotes grain protein accumulation. The results indicate that high-nitrogen treatment leads to an increased grain protein content, wet gluten content, stability time, and energy area. In addition, the β-sheet content of the protein secondary structure increased, while the irregular curl content decreased. A total of 285 DEPs were identified under different nitrogen levels, with 172 upregulated proteins in grains under high-nitrogen treatment including storage proteins (8.14%) and proteins involved in nitrogen metabolism (8.72%), defense/stress (11.04%), regulation (26.16%), and transport (5.23%). This suggests that both storage proteins and certain metabolic proteins contribute to dough network formation. WGCNA revealed a strong correlation between the blue module and grain samples, and Gene Ontology analysis indicated that most genes were enriched in response to abscisic acid (ABA) in the “biological process” category. Furthermore, 18 core genes were identified, with most containing ABA response elements, light response elements, and motifs related to storage protein regulation in their promoter regions. Expression analysis of 10 genes and their predicted transcription factors during the grain-filling stage demonstrated higher expression levels under high-nitrogen conditions. This study provides valuable insights into the promotion of grain protein accumulation and dough quality by nitrogen fertilizer application.

WRKY (WRKY domain-containing) transcription factors represent one of the largest families of plant-specific transcription regulators and play pivotal roles in plant growth, development, nutrient acquisition, and responses to biotic and abiotic stresses. In this study, the coding sequence of TaWRKY65-3B was cloned from the hexaploid wheat cultivar Hanxuan 10. Domain analysis revealed that TaWRKY65-3B contains a conserved WRKY domain and a typical C₂H₂-type zinc finger motif. The gene spans 1478 bp and comprises two exons and one intron. Promoter analysis identified multiple cis-acting regulatory elements, including those responsive to abscisic acid, methyl jasmonate, drought, and low temperature. Quantitative real-time PCR (qRT-PCR) demonstrated that TaWRKY65-3B was significantly upregulated under polyethylene glycol (PEG)-simulated-drought stress in wheat. Overexpression of TaWRKY65-3B in rice resulted in marked growth inhibition, characterized by reduced plant height, shortened grains, and decreased grain width, perimeter, and surface area. These morphological changes led to a significant reduction in thousand-grain weight and overall grain yield. Mechanistically, TaWRKY65-3B activated the expression of OsCPS2, OsCPS4, and OsKS4, which encode key enzymes in the diterpenoid phytoalexin biosynthetic pathway. Subsequent oxidative modifications catalyzed by the cytochrome P450 monooxygenase OsCYP76M7 facilitated the accumulation of the defensive diterpenoid neoabietic acid. Integrated transcriptomic and metabolomic analyses revealed that constitutive TaWRKY65-3B overexpression reprograms simulated-drought-responsive metabolism in rice, with a diterpenoid metabolite annotated as neoabietic acid as a key correlative feature—though definitive structural confirmation requires authentic standards. These findings identify a WRKY-mediated regulatory module connecting diterpenoid phytoalexin metabolism to simulated-drought stress responses, although the precise molecular cascades governing the growth-defence trade-off between stress adaptation and yield warrant further investigation.