2E,4E-Decadienoic Acid, a Novel Anti-Oomycete Agent from Coculture of Bacillus subtilis and Trichoderma asperellum.

Phytophthora nicotianae is an oomycete pathogen of global significance threatening many important crops. It is mainly controlled by chemosynthetic fungicides, which endangers ecosystem and human health; thus, there is an urgent need to explore alternatives for these fungicides. In this study, a new anti-oomycete aliphatic compound, 2E,4E-decadienoic acid (DDA), was obtained through coculture of Bacillus subtilis Tpb55 and Trichoderma asperellum HG1. Both in vitro and in vivo tests showed that DDA had a strong inhibitory effect against P. nicotianae. In addition, rhizosphere microbiome analysis showed that DDA reduced the relative abundance of Oomycota in rhizosphere soil. Transcriptome sequencing (RNA-Seq) analysis revealed that treatment of P. nicotianae with DDA resulted in significant downregulation of antioxidant activity and energy metabolism, including antioxidant enzymes and ATP generation, and upregulation of membrane-destabilizing activity, such as phospholipid synthesis and degradation. The metabolomic analysis results implied that the pathways influenced by DDA were mainly related to carbohydrate metabolism, energy metabolism, and the cell membrane. The biophysical tests further indicated that DDA produced oxidative stress on P. nicotianae, inhibited antioxidant enzyme and ATPase activity, and increased cell membrane permeability. Overall, DDA exerts inhibitory activity by acting on multiple targets in P. nicotianae, especially on the cell membrane and mitochondria, and can therefore serve as a novel environment-friendly agent for controlling crop oomycete disease. IMPORTANCE P. nicotianae is an oomycete pathogen that is destructive to crops. Although some oomycete inhibitors have been used during crop production, most are harmful to the ecology and lead to pathogen resistance. Alternatively, medium-chain fatty acids have been reported to exhibit antimicrobial activity in the medical field in previous studies; however, their potential as biocontrol agents has rarely been evaluated. Our in vivo and in vitro analyses revealed that the medium-chain fatty acid 2E,4E-decadienoic acid (DDA) displayed specific inhibitory activity against oomycetes. Further analysis indicated that DDA may acted on multiple targets in P. nicotianae, especially on the cell membrane and mitochondria. Our findings highlight the potential of DDA in controlling oomycete diseases. In conclusion, these results provide insights regarding the future use of green and environment-friendly anti-oomycete natural products for the prevention and control of crop oomycete diseases.

[Expression of survivin, Bcl-2 and p53 during 4-nitro-quinoline 1-oxide-induced rat tongue carcinogenesis].

OBJECTIVE: To investigate the expression of survivin during oral carcinogenesis and its relationship with the expression of Bcl-2 and p53. METHODS: Two-step immunohistochemical method was employed to detect the expression of survivin, Bcl-2 and p53 in 60 rat tongue carcinogenesis specimens induced by 4-nitro-quinoline 1-oxide (4NQO). RESULTS: Survivin was present in 1/36 cases of normal mucosa, 6/11 cases of oral epithelial dysplasia and 10/11 cases of oral carcinoma. There were significant difference in the expression of survivin among normal mucosa, oral epithelial dysplasia and carcinoma (P < 0.001). While in the 17 cases of positive expression of survivin, Bcl-2 was present in 12 cases and p53 was present in 8 cases. The expression of survivin in oral epithelial dysplasia and carcinoma were significantly higher than that in normal oral mucosa (P < 0.01). The expression of survivin was positively correlated to the expression of Bcl-2 and p53 in rat tongue (P < 0.01). CONCLUSIONS: The expression of survivin may play an important role in oral carcinogenesis. Survivin, Bcl-2 and p53 may be synergetic in the carcinogenesis of oral cancer.