Nε-Acetylation of lysine residues, a frequently occurring post-translational modification, plays important functions in regulating physiology and metabolism. However, the information of global overview of protein acetylome under nitrogen-starvation/resupply in tea (Camellia sinensis) leaves was limited. And the full function of lysine acetylated proteins of tea plants in nitrogen absorption and assimilation remains unclear. Here, we performed the global review of lysine acetylome in tea leaves under nitrogen (N)-starvation/resupply, using peptide prefractionation, immunoaffinity enrichment, and coupling with high sensitive LC-MS/MS combined with affinity purification analysis. Altogether, 2229 lysine acetylation sites on 1286 proteins were identified, of which 16 conserved motifs in E*KacK, Kac*K, Kac*R, Kac*HK, Kac*N, Kac*S, Kac*T, Kac*D, were extracted from 2180 acetylated peptides. Approximately, 36.76% of the acetylated lysines were located in the regions of ordered secondary structures. The most of the identified lysine acetylation proteins were located in the chloroplast (39%) and cytoplasm (29%). The largest group of acetylated proteins consisted of many enzymes, such as ATP synthase, ribosomal proteins and malate dehydrogenase [NADP], which were related to metabolism (38%) in the biological process. These acetylated proteins were mainly enriched in three primary protein complexes of photosynthesis: photosystem I, photosystem II and the cytochrome b6/f complex. And some acetylated proteins related to glycolysis and secondary metabolite biosynthesis were increased/decreased under N-resupply. Moreover, the PPI (protein-protein interaction) analysis revealed that the diverse interactions of identified acetylated proteins mainly involved in photosynthesis and ribosome. The results suggested that lysine acetylated proteins might play regulating roles in metabolic process in tea leaves. The critical regulatory roles mainly involved in diverse aspects of metabolic processes, especially in photosynthesis, glycolysis and secondary metabolism. A lot of proteins related to the photosynthesis and glycolysis were found to be acetylated, including LHCA1, LHCA3, LHCB6, psaE, psaD, psaN, GAPDH, PEPC, ENL and petC. And some proteins related to flavonoids were also found to be acetylated, including PAL, DFR, naringenin 3-dioxygenase and CHI. The provided data may serve as important resources for exploring the physiological, biochemical, and genetic role of lysine acetylation in tea plants. Data are available via ProteomeXchange with identifier PXD008931.

Improving plant water use efficiency (WUE) and drought tolerance by modulating stomatal activity constitutes a promising strategy for mitigating the impacts of water scarcity. SnRK2, a key component of the abscisic acid (ABA) signaling pathway, plays a critical role in modulating stomatal behavior under abiotic stress. However, the functional role of SnRK2 in regulating stomatal movement to enhance WUE and drought tolerance in Populus euphratica remains to be characterized. In this study, 11 PeSnRK2 genes were identified in the P. euphratica genome, each comprising 9–14 exons and exhibiting an uneven distribution across seven chromosomes. Subcellular localization predictions indicated that these proteins are predominantly localized in the Cytoplasm and Cytoskeleton. Phylogenetic analysis grouped the PeSnRK2 genes into three distinct subfamilies, and conserved gene structures were observed within each clade. Analysis of cis-acting regulatory elements suggested that PeSnRK2 genes were involved in hormonal signaling and stress response pathways. Further transcriptomic data also indicated substantial alterations in PeSnRK2 expression due to polyethylene glycol (PEG) and abscisic acid (ABA) treatment. Finally, qRT-PCR and subcellular localization showed that PeSnRK2.6 is highly induced by ABA and functions in both nucleus and cytoplasm. This first characterization in a desert woody species bridged gaps in SnRK2 evolution and function.

To study the genetic diversity of phenotypic traits of natural Populus euphratica populations, we investigated the leaf, fruit and seed traits of the populations. The results of the phenotypic traits all showed that the variation among populations was larger than the variation within populations. The differentiation coefficients of phenotypic traits indicated that the variation among populations was the main source of population variation. The coefficient of variation of the phenotypic traits indicated that the leaf phenotypic traits directly exposed to the environment for a long time had the largest variation in the population. Correlation analysis between the phenotypic traits and environmental factors showed that geographical factors had a greater influence than climatic factors on phenotypic traits, and environmental factors had a certain degree of plasticity for phenotypic variation.

Abscisic acid (ABA) is a key phytohormone involved in regulating plant growth and responses to environmental stress. As receptors of ABA, pyrabactin resistance 1 (PYR)/PYR1-like (PYL) proteins play a central role in initiating ABA signal transduction. In this study, a total of 30 PopPYL genes were identified and classified into three sub-families (PYL I–III) in the pan-genome of 17 Populus species, through phylogenetic analysis. Among these subfamilies, the PYL I subfamily was the largest, comprising 21 members, whereas PYL III was the smallest, with only four members. To elucidate the evolutionary dynamics of these genes, we conducted synteny and Ka/Ks analyses. Results indicated that most PopPYL genes had undergone purifying selection (Ka/Ks < 1), while a few were subject to positive selection (Ka/Ks > 1). Promoter analysis revealed 258 cis-regulatory elements in the PYL genes of Populus euphratica (EUP) and Populus pruinosa (PRU), including 127 elements responsive to abiotic stress and 33 ABA-related elements. Furthermore, six structural variations (SVs) were detected in PYL_EUP genes and significantly influenced gene expression levels (p < 0.05). To further explore the functional roles of PYL genes, we analyzed tissue-specific expression profiles of 17 PYL_EUP genes under drought stress conditions. PYL6_EUP was predominantly expressed in roots, PYL17_EUP exhibited leaf-specific expression, and PYL1_EUP showed elevated expression in stems. These findings suggest that the drought response of PYL_EUP genes is tissue-specific. Overall, this study highlights the utility of pan-genomics in elucidating gene family evolution and suggests that PYL_EUP genes contribute to the regulation of drought stress responses in EUP, offering valuable genetic resources for functional characterization of PYL genes.

All multicellular organisms undergo senescence, but the continuous division of the vascular cambium in plants enables certain tree species to survive for hundreds or even thousands of years. Previous studies have focused on the development of the vascular cambium, but the mechanisms regulating age-related changes remain poorly understood. This study investigated age-related changes in the vascular cambium of P. euphratica trees aged 50 to 350 years. The number of cambium cells in the 50-year-old tree group was 10 ± 2, while the number of cambium cells in the 200-year-old and 350-year-old tree groups significantly decreased. The thickness of the cambium cells exhibited a similar trend. In addition, the net photosynthetic and transpiration rates continue to increase with age, but no notable differences were found in factors like average leaf area, palisade tissue thickness, and stomatal density. A total of 6491 differentially expressed genes (DEGs) were identified in the vascular cambium of P. euphratica at three distinct ages using RNA sequencing. The expression patterns of DEGs associated with cell division and differentiation, lignin biosynthesis, plant hormones, and transcription factors were analyzed. DEGs related to XTH, EXP, PAL, C4H, ABA, Br, GA, and others are highly expressed in older trees, whilst those encoding expansins, kinases, cyclins, 4CL, Auxin, Eth, SA, and others are more prevalent in younger trees. Gene family members, such as NAC, MYB, HD-ZIP III, WRKY, and GRF, have various regulatory functions in the vascular cambium. The findings offer insights into how ancient P. euphratica trees maintain vitality by balancing growth and aging, providing a foundation for future research on their longevity mechanisms.

DNA methylation, mediated by DNA methyltransferases (DMTs) and demethylases (DMLs), is an important epigenetic modification that maintains genomic stability and regulates gene expression in plant growth, development, and stress responses. However, a comprehensive characterization of these gene families in Populus sect. Turanga remains lacking. In this study, eight PeDMT and two PeDML genes were identified in Populus euphratica, and six PpDMT and three PpDML genes in Populus pruinosa. Phylogenetic analysis revealed that DMTs and DMLs could be classified into four and three subfamilies, respectively. The analysis of cis-acting elements indicated that the promoter regions of both DMTs and DMLs were enriched with elements responsive to growth and development, light, phytohormones, and stress. Collinearity analysis detected three segmentally duplicated gene pairs (PeDMT5/8, PeDML1/2, and PpDML2/3), suggesting potential functional diversification. Transcriptome profiling showed that several PeDMTs and PeDMLs exhibited leaf shape- and developmental stage-specific expression patterns, with PeDML1 highly expressed during early stages and in broad-ovate leaves. Whole-genome bisulfite sequencing revealed corresponding decreases in DNA methylation levels, suggesting that active demethylation may contribute to heteromorphic leaf formation. Overall, this study provides significant insights for exploring the functions and expression regulation of plant DMTs and DMLs and will contribute to future research unraveling the molecular mechanisms of epigenetic regulation in P. euphratica.