Induction of <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> Resistance to Pathogenic Bacteria by Lipopolysaccharide and Salicylic Acid

The effects of combined treatment with an elicitor (lipopolysaccharide) and a signaling molecule (salicylic acid) on the disease resistance of wild-type (Col-0) and mutant Arabidopsis thaliana L. plants have been compared. The mutant lines used were jin1 (with impaired jasmonate signaling), npr1 (lacking expression of pathogen-dependent PR genes), and NahG (expressing an active bacterial salicylate hydroxylase transgene). The lipopolysaccharide was isolated from a saprophytic strain (8614) of Pseudomonas aeruginosa bacteria. Treatment of A. thaliana seeds with a composite preparation (lipopolysaccharide and salicylic acid–SA) increased the resistance of seedlings to a subsequent infection by the pathogenic 9096 strain of P. aeruginosa bacteria. The protective effect was more pronounced in jin1 mutant seedlings, which was indicative of the possible compensation of jasmonate signaling impairment due to activation of the SA-dependent signaling pathway. We concluded that a preparation composed of an elicitor and a signaling molecule could affect regulatory mechanism functioning in a plant cell and, in particular, compensate for the absence of a certain signaling pathway by activating another.     

Leaf Extracts of Selected Gardening Trees Can Attenuate Quorum Sensing and Pathogenicity of <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> PAO1

An increasing concern on resistance to multiple-antibiotics has led to the discovery of novel agents and the establishment of new precaution strategy. Numerous plant sources have been widely studied to reduce virulence of pathogenic bacteria by interfering cell-to-cell based communication called quorum sensing (QS). Leaf extracts of 17 gardening trees were collected and investigated for their anti-QS effects using a sensor strain Chromobacterium violaceum CV026. Methanolic extracts of K4 (Acer palmatum), K9 (Acer pseudosieboldianum) and K13 (Cercis chinensis) leaves were selected for further experiments based on their antagonism effect on QS without inhibiting C. violaceum CV026 growth. Subsequently, the leaf extracts on QS-mediated virulence of Pseudomonas aeruginosa PAO1 involved in biofilm formation, motility, bioluminescence, pyocyanin production, QS molecules production, and Caenorhabditis elegans killing activity were evaluated. The biofilm formation ability and swarming motility of P. aeruginosa PAO1 were decreased approximately 50% in the presence of these leaf extracts at a concentration of 1 mg/mL. The expression level of lecA::lux of P. aeruginosa PAO1 and pyocyanin production were also reduced. The three leaf extracts also decreased autoinducer (AI) production in P. aeruginosa PAO1 without direct degradation, suggesting that AI synthesis might have been suppressed by these extracts. The three leaf extracts also showed anti-infection activity in C. elegans model. Taken together, these results suggest that methanolic leaf extracts of K4, K9 and K13 have the potential to attenuate the virulence of P. aeruginosa PAO1.     

Transcriptomic analysis of differentially expressed genes in flower-buds of genetic male sterile and wild type cucumber by RNA sequencing

Cucumber (Cucumis sativus L.) pollen development involves a diverse range of gene interactions between sporophytic and gametophytic tissues. Previous studies in our laboratory showed that male sterility was controlled by a single recessive nuclear gene, and occurred in pollen mother cell meiophase. To fully explore the global gene expression and identify genes related to male sterility, a RNA-seq analysis was adopted in this study. Young male flower-buds (1–2 mm in length) from genetic male sterility (GMS) mutant and homozygous fertile cucumber (WT) were collected for two sequencing libraries. Total 545 differentially expressed genes (DEGs), including 142 up-regulated DEGs and 403 down-regulated DEGs, were detected in two libraries (Fold Change ≥ 2, FDR < 0.01). These genes were involved in a variety of metabolic pathways, like ethylene-activated signaling pathway, sporopollenin biosynthetic pathway, cell cycle and DNA damage repair pathway. qRT-PCR analysis was performed and showed that the correlation between RNA-Seq and qRT-PCR was 0.876. These findings contribute to a better understanding of the mechanism that leads to GMS in cucumber.     

CYP1A1 based on metabolism of xenobiotics by cytochrome P450 regulates chicken male germ cell differentiation

This study aimed to explore the regulatory mechanism of metabolism of xenobiotics by cytochrome P450 during the differentiation process of chicken embryonic stem cells (ESCs) into spermatogonial stem cells (SSCs) and consummate the induction differentiation system of chicken embryonic stem cells (cESCs) into SSCs in vitro. We performed RNA-Seq in highly purified male ESCs, male primordial germ cells (PGCs), and SSCs that are associated with the male germ cell differentiation. Thereinto, the metabolism of xenobiotics by cytochrome P450 was selected and analyzed with Venny among male ESC vs male PGC, male PGC vs SSC, and male ESC vs SSC groups and several candidates differentially expressed genes (DEGs) were excavated. Finally, quantitative real-time PCR (qRT-PCR) detected related DEGs under the condition of retinoic acid (RA) induction in vitro, and the expressions were compared with RNA-Seq. By knocking down CYP1A1, we detected the effect of CYP1A1-mediated metabolism of xenobiotics by cytochrome P450 on male germ cell differentiation by qRT-PCR and immunocytochemistry. Results showed that 17,742 DEGs were found during differentiation of ESCs into SSCs and enriched in 72 differently significant pathways. Thereinto, the metabolism of xenobiotics by cytochrome P450 was involved in the whole differentiation process of ESCs into SSCs and several candidate DEGs: CYP1A1, CYP3A4, CYP2D6, ALDH3B1, and ALDH1A3 were expressed with the same trend with RNA-Seq. Knockdown of CYP1A1 caused male germ cell differentiation under restrictions. Our findings showed that the metabolism of xenobiotics by cytochrome P450 was significantly different during the process of male germ cell differentiation and was persistently activated when we induced cESCs to differentiate into SSCs with RA in vitro, which illustrated that the metabolism of xenobiotics by cytochrome P450 played a crucial role in the differentiation process of ESCs into SSCs.