Revealing plant growth-promoting mechanisms of Bacillus strains in elevating rice growth and its interaction with salt stress.

Soil salinity is a major environmental stress that has been negatively affecting the growth and productivity of rice. However, various salt-resistant plant growth-promoting rhizobacteria (PGPR) have been known to promote plant growth and alleviate the damaging effects of salt stress via mitigating physio-biochemical and molecular characteristics. This study was conducted to examine the salt stress potential of Bacillus strains identified from harsh environments of the Qinghai-Tibetan plateau region of China. The Bacillus strains NMTD17, GBSW22, and FZB42 were screened for their response under different salt stress conditions (1, 4, 7, 9, 11, 13, and 16%). The screening analysis revealed strains NMTD17, GBSW22, and FZB42 to be high-salt tolerant, moderate-salt tolerant, and salt-sensitive, respectively. The NMTD17 strain produced a strong biofilm, followed by GBSW22 and FZB42. The expression of salt stress-related genes in selected strains was also analyzed through qPCR in various salt concentrations. Further, the Bacillus strains were used in pot experiments to study their growth-promoting ability and antioxidant activities at various concentrations (0, 100, 150, and 200 mmol). The analysis of growth-promoting traits in rice exhibited that NMTD17 had a highly significant effect and GSBW22 had a moderately significant effect in comparison with FZB42. The highly resistant strain NMTD17 that stably promoted rice plant growth was further examined for its function in the composition of rhizobacterial communities. The inoculation of NMTD17 increased the relative abundance and richness of rhizobacterial species. These outcomes propose that NMTD17 possesses the potential of PGPR traits, antioxidants enzyme activities, and reshaping the rhizobacterial community that together mitigate the harmful effects of salinity in rice plants.

The autophagy-related proteins FvAtg4 and FvAtg8 are involved in virulence and fumonisin biosynthesis in Fusarium verticillioides.

Autophagy is the main intracellular degradation system by which cytoplasmic materials are transported to and degraded in the vacuole/lysosome of eukaryotic cells, and it also controls cellular differentiation and virulence in a variety of filamentous fungi. However, the contribution of the autophagic pathway to fungal development and pathogenicity in the important maize pathogen and mycotoxigenic fungus Fusarium verticillioides is still unknown. In this study, we characterized two autophagy-related proteins, FvAtg4 and FvAtg8. The F. verticillioides deletion mutants ΔFvAtg4 and ΔFvAtg8 were impaired in autophagosome formation, aerial hyphal formation, sexual growth, lipid turnover, pigmentation and fungal virulence. Interestingly, ΔFvAtg4 and ΔFvAtg8 were defective in fumonisin B1 (FB1) synthesis, which may have resulted from decreased intracellular levels of alanine in the mutants. Our results indicate that FvAtg4 and FvAtg8 contribute to F. verticillioides pathogenicity by regulating the autophagic pathway to control lipid turnover, fumonisin biosynthesis, and pigmentation during its infectious cycle.

miR-942-5p promotes the proliferation and invasion of human melanoma cells by targeting DKK3.

OBJECTIVE: The purpose of this study was to figure out the dysregulation of miR-942-5p in melanoma and its role in melanoma pathogenesis. METHODS: Quantitative real-time PCR (qRT-PCR) assay was used to determine the change of RNA expression. Protein expression was examined by Western blotting. miRNA target was validated through TargetScan and luciferase assay. Cell migration and invasion were detected by wound healing and transwell assay, respectively. RESULTS: Results of qRT-PCR manifested miR-942-5p were upregulated in melanoma cell. High expression of miR-942-5p in melanoma patients presented a poor prognosis. Upregulation of miR-942-5p accelerated cell proliferation, migration, and invasion in melanoma cells. Cell apoptosis was inhibited by miR-942-5p mimics. Suppression of miR-942-5p by its inhibitor showed the opposite effects in melanoma cells. TargetScan and luciferase assay showed that miR-942-5p directly targeted to the 3'-untranslated region (3'-UTR) of DKK3. Overexpression of DKK3 inhibited GSK-3ß phosphorylation and reduced the expression of ß-catenin in both cytoplasm and nucleus, which were induced by miR-942-5p mimics leading to the activation of Wnt/ß-catenin pathway. CONCLUSION: Upregulation of miR-942-5p was observed in melanoma cells and tissues and significantly associated with a poor prognosis. Though targeting 3'-UTR of DKK3, miR-942-5p could activate Wnt/ß-catenin pathway, resulting in melanoma cell proliferation, migration, and invasion, which promoted the development of melanoma. These results showed that miR-942-5p might be a diagnosis and prognosis biomarker in melanoma.

Oroxylin A reverses hypoxia-induced cisplatin resistance through inhibiting HIF-1α mediated XPC transcription.

Hypoxia is a key concern during the treatment of non-small cell lung cancer (NSCLC), and hypoxia-inducible factor 1 alpha (HIF-1α) has been associated with increased tumor resistance to therapeutic modalities such as cisplatin. Compensatory activation of nucleotide excision repair (NER) pathway is the major mechanism that accounts for cisplatin resistance. In the present study, we suggest a novel strategy to improve the treatment of NSCLC and overcome the hypoxia-induced cisplatin resistance by cotreatment with Oroxylin A, one of the main bioactive flavonoids of Scutellariae radix. Based on the preliminary screening, we found that xeroderma pigmentosum group C (XPC), an important DNA damage recognition protein involved in NER, dramatically increased in hypoxic condition and contributed to hypoxia-induced cisplatin resistance. Further data suggested that Oroxylin A significantly reversed the hypoxia-induced cisplatin resistance through directly binding to HIF-1α bHLH-PAS domain and blocking its binding to HRE3 transcription factor binding sites on XPC promoter which is important to hypoxia-induced XPC transcription. Taken together, our findings not only demonstrate a crucial role of XPC dependent NER in hypoxia-induced cisplatin resistance, but also suggest a previously unrecognized tumor suppressive mechanism of Oroxylin A in NSCLC which through sensitization of cisplatin-mediated growth inhibition and apoptosis under hypoxia.

Fengycin Produced by Bacillus amyloliquefaciens FZB42 Inhibits Fusarium graminearum Growth and Mycotoxins Biosynthesis.

Fusarium graminearum is a notorious pathogen that causes Fusarium head blight (FHB) in cereal crops. It produces secondary metabolites, such as deoxynivalenol, diminishing grain quality and leading to lesser crop yield. Many strategies have been developed to combat this pathogenic fungus; however, considering the lack of resistant cultivars and likelihood of environmental hazards upon using chemical pesticides, efforts have shifted toward the biocontrol of plant diseases, which is a sustainable and eco-friendly approach. Fengycin, derived from Bacillus amyloliquefaciens FZB42, was purified from the crude extract by HPLC and further analyzed by MALDI-TOF-MS. Its application resulted in structural deformations in fungal hyphae, as observed via scanning electron microscopy. In planta experiment revealed the ability of fengycin to suppress F. graminearum growth and highlighted its capacity to combat disease incidence. Fengycin significantly suppressed F. graminearum, and also reduced the deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-ADON), 15-acetyldeoxynivalenol (15-ADON), and zearalenone (ZEN) production in infected grains. To conclude, we report that fengycin produced by B. amyloliquefaciens FZB42 has potential as a biocontrol agent against F. graminearum and can also inhibit the mycotoxins produced by this fungus.

TLR3 regulates PD-L1 expression in human cytomegalovirus infected glioblastoma.

Glioblastoma, the most common primary brain tumor of adults, is characterized by poor survival rates. Programmed death ligand 1 (PD-L1, CD274) has been implicated in the immune escape of glioblastoma. The presence of human cytomegalovirus (HCMV) in glioblastoma multiforme (GBM) has sparked considerable interest and controversy. The exposure of toll-like receptor 3 (TLR3) to pathogens induces an antiviral state in cells or in animals. In the current study, the expression of PD-L1 and TLR3 in HCMV-infected glioma specimens was observed to be higher compared to the control. We therefore investigated if PD-L1 expression in glioblastoma is mediated by TLR3 triggering in HCMV infected glioblastoma. TLR3 siRNA transfections were utilized to identify the induction of PD-L1 via TLR3 triggering in HCMV infected cell lines. Also, IL-8 and TGF-ß were detected by ELISA for the antitumor role of TLR3. Thus, we propose a novel immune treatment using a combination of PD-L1 blockade with TLR3 triggering against HCMV infected glioblastoma.

Functional analysis of flavonoid 3',5'-hydroxylase from tea plant (Camellia sinensis): critical role in the accumulation of catechins.

BACKGROUND: Flavonoid 3',5'-hydroxylase (F3'5'H), an important branch point enzyme in tea plant flavan-3-ol synthesis, belongs to the CYP75A subfamily and catalyzes the conversion of flavones, flavanones, dihydroflavonols and flavonols into 3',4',5'-hydroxylated derivatives. However, whether B-ring hydroxylation occurs at the level of flavanones and/or dihydroflavonols, in vivo remains unknown. RESULTS: The Camellia sinensis F3'5'H (CsF3'5'H) gene was isolated from tea cDNA library. Expression pattern analysis revealed that CsF3'5'H expression was tissue specific, very high in the buds and extremely low in the roots. CsF3'5'H expression was enhanced by light and sucrose. Over-expression of CsF3'5'H produced new-delphinidin derivatives, and increased the cyanidin derivative content of corollas of transgenic tobacco plants, resulting in the deeper transgenic plant flower color. Heterologous expressions of CsF3'5'H in yeast were carried out to demonstrate the function of CsF3'5'H enzyme in vitro. Heterologous expression of the modified CsF3'5'H (CsF3'5'H gene fused with Vitis vinifera signal peptide, FSI) revealed that 4'-hydroxylated flavanone (naringenin, N) is the optimum substrate for CsF3'5'H, and was efficiently converted into both 3'4'- and 3'4'5'-forms. The ratio of 3'4'5'- to 3'4'-hydroxylated products in FSI transgenic cells was significantly higher than VvF3'5'H cells. CONCLUSIONS: CsF3'5'H is a key controller of tri-hydroxyl flavan-3-ol synthesis in tea plants, which can effectively convert 4'-hydroxylated flavanone into 3'4'5'- and/or 3'4'-hydroxylated products. These findings provide animportant basis for further studies of flavonoid biosynthesis in tea plants. Such studies would help accelerate flavonoid metabolic engineering in order to increase B-ring tri-hydroxyl product yields.

Effect of low-intensity white light mediated de-etiolation on the biosynthesis of polyphenols in tea seedlings.

Light is an important source of energy as well as environmental signal for the regulation of biosynthesis and accumulation of multiple secondary metabolites in plants. Polyphenols are the major class of secondary metabolites in tea, which possess potential antioxidant properties. In order to investigate the effect of light signal on the regulation of biosynthesis and accumulation of polyphenols in tea seedlings, a low-intensity white light was used and the change in trends of polyphenol contents, patterns of gene expression, and corresponding enzymatic activities were studied. LC-TOF/MS analysis revealed that light signal promoted the accumulation of hydroxycinnamic acid derivatives and nongalloylated catechin (EGC), while it restrained the accumulation of ß-glucogallin and galloylated catechins. The quantitative reverse transcription-PCR analysis showed that the expression levels of the regulator genes and some structural genes involved in photomorphogenesis and biosynthetic pathway of nongalloylated catechins, respectively, were up-regulated. In contrast, the expression of DHD/SDH and UGT genes, which may be involved in biosynthetic pathway of ßG, was down-regulated. The corresponding in vitro enzyme assays revealed decrease in the activity of ECGT (galloylates nongalloylated catechins) and an increase in activity of GCH (hydrolyzes galloylated catechins) during de-etiolation. The present study yielded inconsistent accumulation patterns of phenolic acids, flavan-3-ols, and flavonols in tea seedlings during de-etiolation. In addition, the accumulation of catechins was possibly jointly influenced by the biosynthesis, hydrolysis, glycosylation, and galloylation of polyphenols in tea plants.

[Controlled study of auricular point taping and pressing therapy for treatment of vascular dementia].

OBJECTIVE: To assess the therapeutic effect of auricular point taping and pressing therapy on vascular dementia (VD). METHODS: One hundred and eighty cases of vascular dementia were randomly divided into an auricular point taping and pressing group and a western medicine group, 90 cases in each group. The auricular point taping and pressing group was treated by auricular point taping and pressing at auricular points Shennen, Nao (brain), Shen (kidney), Zhen (pulvinal), and the western medicine group by oral administration of Nimodipine, thrice each day, 30 mg each time. They were treated for 12 weeks. The scores of mini-mental state examination (MMSE) and activities of daily living (ADL), and adverse reaction were observed. RESULTS: The scores of MMSE before treatment and 12 weeks after treatment were 18.00 +/- 3.88 and 20.83 +/- 3.74 in the auricular point taping and pressing group, and 17.80 +/- 3.82 and 20.70 +/- 3.53 in the western medicine group, respectively, with significant increases in scores of MMSE after treatment in the two groups (both P < 0.01) and with no significant difference between the two groups (P > 0.05). The scores of ADL before treatment and 12 weeks after treatment were 44.90 +/- 14.84 and 39.60 +/- 12.45 in the auricular point taping and pressing group, and 45.70 +/- 14.86 and 39.10 +/- 13.44 in the western medicine group, respectively, with significant decreases after treatment in the two groups (both P < 0.01) and with no significant difference between the two groups (P > 0.05). In the auricular point taping and pressing group, 2 cases withdrew from the test because adhesive plaster allergic reaction induced severe itch of the auricle. In the western medicine group, one case had mild dizziness and another case had diarrhea respectively. CONCLUSION: Auricular point taping and pressing and Nimodipine have similar therapeutic effect on vascular dementia, and have no obvious adverse reaction, except adhesive plaster allergic reaction.