Growth, Enzymatic, and Transcriptomic Analysis of xyr1 Deletion Reveals a Major Regulator of Plant Biomass-Degrading Enzymes in Trichoderma harzianum.

The regulation of plant biomass degradation by fungi is critical to the carbon cycle, and applications in bioproducts and biocontrol. Trichoderma harzianum is an important plant biomass degrader, enzyme producer, and biocontrol agent, but few putative major transcriptional regulators have been deleted in this species. The T. harzianum ortholog of the transcriptional activator XYR1/XlnR/XLR-1 was deleted, and the mutant strains were analyzed through growth profiling, enzymatic activities, and transcriptomics on cellulose. From plate cultures, the Δxyr1 mutant had reduced growth on D-xylose, xylan, and cellulose, and from shake-flask cultures with cellulose, the Δxyr1 mutant had ~90% lower ß-glucosidase activity, and no detectable ß-xylosidase or cellulase activity. The comparison of the transcriptomes from 18 h shake-flask cultures on D-fructose, without a carbon source, and cellulose, showed major effects of XYR1 deletion whereby the Δxyr1 mutant on cellulose was transcriptionally most similar to the cultures without a carbon source. The cellulose induced 43 plant biomass-degrading CAZymes including xylanases as well as cellulases, and most of these had massively lower expression in the Δxyr1 mutant. The expression of a subset of carbon catabolic enzymes, other transcription factors, and sugar transporters was also lower in the Δxyr1 mutant on cellulose. In summary, T. harzianum XYR1 is the master regulator of cellulases and xylanases, as well as regulating carbon catabolic enzymes.

Volatile Organic Compounds Emitted by the Biocontrol Agent Pythium oligandrum Contribute to Ginger Plant Growth and Disease Resistance.

The oomycete Pythium oligandrum is a potential biocontrol agent to control a wide range of fungal and oomycete-caused diseases, such as Pythium myriotylum-caused rhizome rot in ginger, leading to reduced yields and compromised quality. Previously, P. oligandrum has been studied for its plant growth-promoting potential by auxin production and induction of disease resistance by elicitors such as oligandrin. Volatile organic compounds (VOCs) play beneficial roles in sustainable agriculture by enhancing plant growth and resistance. We investigated the contribution of P. oligandrum-produced VOCs on plant growth and disease suppression by initially using Nicotiana benthamiana plants for screening. P. oligandrum VOCs significantly enhanced tobacco seedling and plant biomass contents. Screening of the individual VOCs showed that 3-octanone and hexadecane promoted the growth of tobacco seedlings. The total VOCs from P. oligandrum also enhanced the shoot and root growth of ginger plants. Transcriptomic analysis showed a higher expression of genes related to plant growth hormones and stress responses in the leaves of ginger plants exposed to P. oligandrum VOCs. The concentrations of plant growth hormones such as auxin, zeatin, and gibberellic acid were higher in the leaves of ginger plants exposed to P. oligandrum VOCs. In a ginger disease biocontrol assay, the VOC-exposed ginger plants infected with P. myriotylum had lower levels of disease severity. We conclude that this study contributes to understanding the growth-promoting mechanisms of P. oligandrum on ginger and tobacco, priming of ginger plants against various stresses, and the mechanisms of action of P. oligandrum as a biocontrol agent. IMPORTANCE Plant growth promotion plays a vital role in enhancing production of agricultural crops, and Pythium oligandrum is known for its plant growth-promoting potential through production of auxins and induction of resistance by elicitors. This study highlights the significance of P. oligandrum-produced VOCs in plant growth promotion and disease resistance. Transcriptomic analyses of leaves of ginger plants exposed to P. oligandrum VOCs revealed the upregulation of genes involved in plant growth hormone signaling and stress responses. Moreover, the concentration of growth hormones significantly increased in P. oligandrum VOC-exposed ginger plants. Additionally, the disease severity was reduced in P. myriotylum-infected ginger plants exposed to P. oligandrum VOCs. In ginger, P. myriotylum-caused rhizome rot disease results in severe losses, and biocontrol has a role as part of an integrated pest management strategy for rhizome rot disease. Overall, growth enhancement and disease reduction in plants exposed to P. oligandrum-produced VOCs contribute to its role as a biocontrol agent.

miR-139-5p inhibits proliferation and invasion of epithelial ovarian cancer cells by targeting Notch1 / 中国肿瘤生物治疗杂志

@# Objective: To explore the action mechanism of miR-139-5p inhibiting proliferation and invasion of epithelial ovarian cancer (EOC) cells by targetedly regulatingNotch1.Methods: A total of 24 pairs of EOC tissues and its corresponding para-cancerous tissues from patients, who underwent surgical resection in the DepartmentofGynecology,Nanyang Central Hospital of Henan Province, were collected for this study; in addition, human ovarian cancer cell lines (SKOV3, ES2, HEY-T30) and human ovarian epithelial cell line IOSE80 were also collected. Real-time quantitative PCR (qPCR) was applied to detectmRNAexpressionofmiR-139-5pandNotch1 in EOC tissues and cell lines. The miR-139-5p over-expression vector and recombinant plasmid pLV-Notch1 were transfected into SKOV3 cells. Blank control group (Ctrl group) and negative control group (NC group) were set up. Dual luciferase reporter gene assay was applied to verify the targeting relationship between miR-139-5p and Notch1 3'-UTR. CCK-8, Transwell and Scratch healing experiments were applied to detect cell proliferationinvasionandmigration, respectively. Western blotting was applied to detect expressions of proliferation and migration related proteins in cells. Results: Compared with para-cancerous tissues and IOSE80 cells, the expression of miR-139-5p was significantly decreased in EOC tissues and cell lines, while the expression of Notch1 mRNA was significantly increased (all P<0.01). The results of Dual luciferase reporter showed that Notch1 was the downstream target gene of miR-139-5p. Compared with NC group, cell proliferation, invasion and migration ability, expression levels of Notch1, NICD, Cyclin D1, Cyclin A1, Snail1, β-catenin and N-cadherin were all significantly decreased on 3 d in miR-139-5p mimic group (all P<0.01), while expression of E-cadherin was significantly increased (P<0.01); meanwhile, over-expression of Notch1 could reverse the inhibitory effect of miR-1395p on proliferation, invasion and migration of SKOV3 cells. Conclusion: miR-139-5p can targetedly regulate Notch1 to inhibit proliferation, invasion and migration of EOC cells, which may be related to its down-regulation of NICD, Cyclin D1, Cyclin A1, Snail1, βcatenin and N-cadherin, and up-regulation of E-cadherin.