Huawei Liu

Soil salinization represents a significant constraint on global agricultural development. Although several NAC gene families have been implicated in the response to salt stress, the mechanisms underlying salt stress tolerance remain unclear, particularly in perennial fruit trees. In this study, we identify MdJUB1, a NAC transcription factor, as a key regulator of salt stress response in apple. Under salt stress, MdJUB1 increases γ-aminobutyric acid (GABA) content, thereby positively regulating salt stress tolerance in apple. Further analysis using yeast one-hybrid, luciferase assays, and electrophoretic mobility shift assays demonstrated that MdJUB1 directly binds to the promoter of MdGAD1, promoting GABA synthesis. Additionally, under salt stress, overexpression of MdJUB1 increased the Na+/K+ ratio in apple. MdJUB1 also binds to the promoters of MdNHX1, MdHKT1, and MdSOS3, activating their expression. Using yeast two-hybrid screening, we identified MdDOF2.4 as an interactor of MdJUB1 and found that MdDOF2.4 positively regulates salt stress tolerance. Importantly, the interaction between MdDOF2.4 and MdJUB1 enhances the expression of downstream genes, including MdGAD1, MdNHX1, MdHKT1, and MdSOS3. Our results demonstrate that MdJUB1 is involved in the regulation of GABA levels and the maintenance of Na+/K+ homeostasis, which may contribute to enhanced salt tolerance in apple.

Valsa mali is a devastating fungal pathogen that causes systemic necrosis and trunk dieback in apple trees, a disease widely known as ‘apple canker’. While this pathogen poses a serious threat to woody plants, the molecular basis of host resistance remains poorly understood. Here, we investigated whether long non-coding RNAs (lncRNAs) contribute to defence against V. mali in Malus sieversii. Through systematic screening, we identified a key pathogen-responsive MsLNC1, 388-nt sense lncRNA. Ectopic overexpression of MsLNC1 enhanced resistance, whereas its knockdown compromised resistance in apple plantlets. MsLNC1 is downstream of MsWRKY65, which exerts its regulatory effect by binding to the W-box motif within its promotor. MsWRKY65 acts as a positive regulator in mediating the resistance of M. sieversii to V. mali. Additionally, thioredoxin H5 (MsTRX5), the neighboring gene of MsLNC1, exhibits a significant resistance function against V. mali. Genetic and molecular evidence demonstrates that MsLNC1, which binds to two 20-bp homologous regions with the MsTRX5 promoter, and physically interacts with RNA Polymerase II (Pol II) components, enhances MsTRX5 transcription. Collectively, our results demonstrate that MsLNC1 functions upstream of MsTRX5 and, together with MsWRKY65, forms a previously uncharacterized regulatory module that controls V. mali resistance in wild apple.

Drought stress affects plant growth and development. Zeaxanthin, as the key substance of the xanthophyll cycle and the precursor to abscisic acid (ABA), whose synthesis depends on light, can quickly respond to drought stress and enhance plant drought tolerance. However, the molecular mechanism by which zeaxanthin adapts to drought stress is still unclear. In this study, the application of exogenous zeaxanthin via spraying was confirmed to alleviate the damage caused by drought stress in apple seedlings, and MdBCH1 and MdLCYB2, which encode proteins that catalyze zeaxanthin synthesis, enhanced drought resistance by accelerating the lutein cycle and ABA synthesis. Furthermore, a transcription factor, MdPIF4, was identified as effectively reducing the contents of zeaxanthin and ABA and negatively regulating drought resistance. Further studies confirmed that MdPIF4 inhibits zeaxanthin biosynthesis by binding to the promoters of MdBCH1 and MdLCYB2. Therefore, this study revealed the regulation of drought resistance and zeaxanthin homeostasis in apple by the MdPIF4-MdBCH1/MdLCYB2 module. These findings provide insights into the molecular mechanisms of drought resistance in plants.

The prevalence of ulcerative colitis (UC) increases with unhealthy eating habits. Both surgery and medication have the potential to treat the condition, but they may also have more negative effects. This study investigated the anti‐inflammatory mechanism of 20% and 40% doses of different highland barley (HB) components (whole grain, peeled, and bran) in a 2% dextran sulfate sodium induced UC mouse model. The results showed that supplementation with a 20% dose of peeled HB restored body weight, disease activity index, colon length, serum interleukin‐1β and interleukin‐10 levels, liver glutathione peroxidase content, and superoxide dismutase activity to normal levels in mice compared to UC mice. Moreover, the damage caused by UC to the mice's colon was significantly reduced, and the relative expression levels of interleukin‐1β, interleukin‐6, and tumor necrosis factor‐α were all significantly downregulated. Additionally, it increased the abundance of Bacteroidota and Firmicutes, improving the balance of gut microbiota.

Chitinases are enzymes that catalyze the hydrolysis of chitin and play a significant biophysiological role in fungal growth, development, and pathogenesis. Valsa mali is a necrotrophic fungus that is a primary contributor to apple Valsa canker. Our study focused on the identification of chitinase gene families from V. mali and the analysis of their expression profiles during infection and nutritional growth. A phylogenetic analysis and conservation of catalytic domains were used to classify these genes into three classes, and their chromosome distribution was random. The qRT-PCR analysis identified five differentially expressed VmGH18 genes during infection and nutritional growth. GH18 chitinases use glutamate, whereas VmGH18-4 (VM1G_05900) and VmGH18-10 (VM1G_03597) use glutamine as the catalytic motif. To further test whether it can induce cell death in apple, the recombinant protein was produced in E. coli. It showed that the purified VmGH18-4 recombinant protein retained cell-death inducing activity, and it could also induce cell death in apple. But the enzyme activity shows that neither VmGH18-4 nor VmGH18-10 have chitinases enzyme activity. These results suggest that VmGH18-4 can elicit cell death in multiple plant species, while VmGH18-10 cannot.

In China, the genus Tulipa L. has been identified as a national second-class protected plant. Due to the complex evolutionary and genetic backgrounds of tulips, the taxonomy of the genus Tulipa and its species remains a matter of dispute. The current study is dedicated to clarifying the taxonomic relationship between two closely related species, T. iliensis and Tulipa thianschanica, by integrating morphological, karyotypic, and molecular evidence—a novel framework for resolving taxonomic ambiguities in closely related species. Morphological analyses showed significant differences in filament shape, pistil length, overall plant height, presence or absence of stem hairs, and perianth length and width, which supports the conclusion that they are distinct species (p < 0.001). Karyotype analysis further verified disparities in their chromosome morphology, and distinct karyotype indices and scatter plot distributions suggest differences between the two species. Molecular phylogenetic analyses using Internal Transcribed Spacer sequences (ITSs) and chloroplast genomes confirmed the genetic differences between T. iliensis and T. thianschanica, and there is evidence indicating the possible occurrence of hybridization events. The research findings demonstrate that T. thianschanica and T. iliensis are independent species, thereby providing valuable insights into the taxonomy of wild tulips and contributing to the conservation of these protected species.

De novo organogenesis from somatic cells to the entire plant represents a remarkable biological phenomenon, but the underlying regulatory mechanism, particularly at the epigenetic level, remains obscure. In this work, we demonstrate the important role of histone deacetylases (HDACs) in shoot organogenesis. HDAC inhibition by trichostatin A (an HDAC inhibitor) at the callus induction stage promotes shoot formation in wounded roots and circumvents tissue wounding to initiate shoot regeneration in unwounded roots. This HDAC inhibition-mediated promotion of shoot organogenesis in wounded roots is associated with the concomitant upregulation of the wound signaling pathway (WOUND INDUCED DEDIFFERENTIATION 4, ENHANCER OF SHOOT REGENERATION1, ISOPENTENYLTRANSFERASE 5, CUP-SHAPED COTYLEDON 2 etc.) and the ARF-LBD pathway (AUXIN RESPONSE FACTOR 19, LATERAL ORGAN BOUNDARIES-DOMAIN 29, etc.) and the downregulation of auxin biosynthesis and reduced auxin content. Furthermore, inhibiting HDACs enhances the local enrichment of histone 3 lysine 9/lysine 14 acetylation at ISOPENTENYLTRANSFERASE 5, supporting the role of histone acetylation in its transcriptional regulation. On the other hand, the HDAC inhibition-associated activation of shoot organogenesis from unwounded roots is coupled with increased expression of the ARF-LBD pathway gene LATERAL ORGAN BOUNDARIES-DOMAIN 29 while bypassing the wound signaling or auxin biosynthetic genes. These findings provide novel insights into the regulatory mechanisms underlying de novo shoot organogenesis and lay a foundation for the improvement of plant transformation technologies.

Curcumin is a polyphenolic compound that has been widely investigated for its health benefits. However, the clinical relevance of curcumin is limited due to its low water solubility and inefficient absorption. Therefore, curcumin is often encapsulated in nanocarriers to improve its delivery and function. In this study, composite nanoparticles composed of stearic acid-modified chitosan (SA-CS) and sodium caseinate (NaCas) were formed using sodium periodate-oxidized dextran with different molecular weights as a crosslinking agent. The effects of oxidized dextran (Odex) with different molecular weights on the composite nanoparticles were compared. The optimal SA-CS/NaCas/Odex composite nanoparticle (NPO) was obtained using an Odex (150 kDa)-to-SA-CS mass ratio of 2:1. Its size, polydispersity index (PDI), and zeta potential (ZP) were 130.2 nm, 0.149, and 25.4 mV, respectively. The particles were highly stable in simulated gastric fluid (SGF) in vitro, and their size and PDI were 172.3 nm and 0.263, respectively. The encapsulation rate of NPO loaded with curcumin (Cur-NPO) was 93% under optimal ultrasonic conditions. Compared with free curcumin, the sustained release of Cur-NPO significantly reduced to 17.9%, and free-radical-scavenging ability improved to 78.7%. In general, the optimal prepared NPO exhibited good GI stability and has potential applications in the formulation of orally bioactive hydrophobic drugs.

Lipoxygenase (EC1.13.11.12, LOX) has been potentially used in the food industry for food quality improvement. However, the low activity, poor thermal stability, narrow range of pH stability, as well as undesirable isoenzymes and off-flavors, have hampered the application of current commercial LOX. In this study, a putative mini-lipoxygenase gene from cyanobacteria, Nostoc sphaeroides (NsLOX), was cloned and expressed in E. coli BL21. NsLOX displayed only 26.62% structural identity with the reported LOX from Cyanothece sp., indicating it as a novel LOX. The purified NsLOX showed the maximum activity at pH 8.0 and 15 °C, with superior stability at a pH range from 6.0 to 13.0, retaining about 40% activity at 40 °C for 90 min. Notably, NsLOX exhibited the highest specific activity of 78,080 U/mg towards linoleic acid (LA), and the kinetic parameters—K_m, k_cat, and k_cat/K_m—attain values of 19.46 μM, 9199.75 s⁻¹, and 473.85 μM⁻¹ s⁻¹, respectively. Moreover, the activity of NsLOX was obviously activated by Ca²⁺, but it was completely inhibited by Zn²⁺ and Cu²⁺. Finally, NsLOX was supplied in steamed bread and contributed even better improved bread quality than the commercial LOX. These results suggest NsLOX as a promising substitute of current commercial LOX for application in the food industry.

Surfactin from Bacillus amyloliquefaciens fmb50 was utilized to treat mice with type 2 diabetes (T2DM) induced by a high-fat diet/streptozotocin (HFD/STZ). Our group’s earlier research indicated that surfactin could lower blood glucose and mitigate liver dysfunction to further improve HFD/STZ-induced T2DM through modulating intestinal microbiota. Thus, we further investigated the effects of surfactin on the pancreas and colon in mice with T2DM to elucidate the detailed mechanism. In the present study, mice with HFD/STZ-induced T2DM had their pancreatic and colon inflammation, oxidative stress, and endoplasmic reticulum stress (ERS) reduced when given oral surfactin at a dose of 80 mg/kg body weight. According to further research, surfactin also improved glucose metabolism by activating the phosphatidylinositol kinase (PI3K)/protein kinase B (Akt) signaling pathway, further protecting islets β-cell, promoting insulin secretion, inhibiting glucagon release and mitigating pancreas dysfunction. Additionally, after surfactin treatment, the colon levels of the tight junction proteins Occludin and Claudin-1 of T2DM mice were considerably increased by 130.64% and by 36.40%, respectively. These findings revealed that surfactin not only ameliorated HFD/STZ-induced pancreas inflammation and dysfunction and preserved intestinal barrier dysfunction and gut microbiota homeostasis but also enhanced insulin sensitivity and glucose homeostasis in T2DM mice. Finally, in the further experiment, we were able to demonstrate that early surfactin intervention might delay the development of T2DM caused by HFD/STZ, according to critical biochemical parameters in serum.